Design and Implementation of a Reconfigurable Radio Platform by YAdocs

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Wireless communications is a technology in continuous evolution, introducing new services and applications techniques which permit dynamic spectrum alloca- tion. Communication devices will need to support several protocols at different frequencies. The hardware required for this ability will need to move seamlessly between these protocols and frequencies without interruption to the communi- cation session. One such technology capable of meeting these requirements is software defined radio. This thesis describes the features and capabilities of the reconfigurable radio platform which was developed in the Institute of Microelec- tronic and Wireless Systems (IMWS), Maynooth as part of the CTVR effort in cognitive radio systems. The platform is designed to operate in a frequency band from 1.6GHz to 2.5GHz and support the DCS1800, PCS 1900, UMTS-FDD, UMTS-TDD and 802.11b standards. However, since two test licenses of 25 MHz have been provided by COMREG (the Irish telecommunications regulator) to the CTVR (Centre for Telecommunications Value-Chain Research) for use by its member institutions at the center frequencies of 2.085GHz and 2.35GHz, these have been used as testing frequencies during the development of the platform.

More Info
									Design and Implementation of a
Reconfigurable Radio Platform

                            by

                  Livia Ruiz Soriano


                   A Thesis presented to

             the National University of Ireland

     in fulfillment of the requirements for the degree of



                     M.Eng.Sc


           Department of Electronic Engineering

                    NUI,Maynooth
                          Ireland




                       May 2007


  Supervisor of Research: Dr.Ronan Farrell

    Head of Department: Frank Devitt
All this work is dedicated to mum, dad, Ignacio and Barbara.
Table of Contents

1 INTRODUCTION                                                                                     1
  1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                     1
  1.2 Contributions of this work . . . . . . . . . . . . . . . . . . . . . .                       2
  1.3 Organization of Thesis . . . . . . . . . . . . . . . . . . . . . . . .                       2

2 RADIO SYSTEMS                                                                                     3
  2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . .               .   .   .    3
  2.2 Evolution of Radio System . . . . . . . . . . . . . . . . . . .                  .   .   .    3
      2.2.1 Early Beginnings . . . . . . . . . . . . . . . . . . . .                   .   .   .    4
      2.2.2 Superheterodyne Architecture . . . . . . . . . . . . .                     .   .   .    4
      2.2.3 IF Sampling Architecture . . . . . . . . . . . . . . . .                   .   .   .    5
      2.2.4 Direct Conversion Architecture . . . . . . . . . . . .                     .   .   .    6
      2.2.5 Near-Zero-IF or Low IF Architecture . . . . . . . . .                      .   .   .    7
      2.2.6 Software Defined Radio . . . . . . . . . . . . . . . . .                    .   .   .    7
             SDR Evolution . . . . . . . . . . . . . . . . . . . . .                   .   .   .    8
             Advantages and Drawbacks of Software Defined Radio                         .   .   .   10
             Applications of Software Defined Radio . . . . . . . .                     .   .   .   11
             Technology Structure . . . . . . . . . . . . . . . . . .                  .   .   .   12
  2.3 Wireless Standard Evolution . . . . . . . . . . . . . . . . . .                  .   .   .   15
  2.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . .               .   .   .   19

3 REQUIREMENTS AND SPECIFICATIONS                                                                  20
  3.1 Introduction . . . . . . . . . . . . . . . . . . . . .   .   .   .   .   .   .   .   .   .   20
  3.2 Standard Specifications . . . . . . . . . . . . . . .     .   .   .   .   .   .   .   .   .   20
  3.3 System Specifications . . . . . . . . . . . . . . . .     .   .   .   .   .   .   .   .   .   22
      3.3.1 Radio Frequency Specifications . . . . . . .        .   .   .   .   .   .   .   .   .   23
             Receiver Specifications . . . . . . . . . . .      .   .   .   .   .   .   .   .   .   23
             Transmitter Specifications . . . . . . . . .       .   .   .   .   .   .   .   .   .   30
      3.3.2 Analog-to-Digital Conversion Specifications         .   .   .   .   .   .   .   .   .   32
  3.4 Implemented Architecture . . . . . . . . . . . . .       .   .   .   .   .   .   .   .   .   38
      3.4.1 SDR Specifications and Block Diagram . .            .   .   .   .   .   .   .   .   .   40
  3.5 Conclusion . . . . . . . . . . . . . . . . . . . . . .   .   .   .   .   .   .   .   .   .   40


                                         i
4 PLATFORM DESIGN                                                                                                    42
  4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . .                               .   .   .   .   42
  4.2 Platform Overview . . . . . . . . . . . . . . . . . . . . . .                                  .   .   .   .   43
  4.3 USB Interface and Digital Control Plane . . . . . . . . . .                                    .   .   .   .   44
      4.3.1 Synchronization and Control . . . . . . . . . . . . .                                    .   .   .   .   44
  4.4 Analog to Digital and Digital to Analog Conversion Stages                                      .   .   .   .   44
      4.4.1 Implementation . . . . . . . . . . . . . . . . . . . .                                   .   .   .   .   46
             ADCs . . . . . . . . . . . . . . . . . . . . . . . . .                                  .   .   .   .   46
             DACs . . . . . . . . . . . . . . . . . . . . . . . . .                                  .   .   .   .   48
  4.5 Baseband Signal Processing . . . . . . . . . . . . . . . . .                                   .   .   .   .   48
      4.5.1 Filtering . . . . . . . . . . . . . . . . . . . . . . . .                                .   .   .   .   49
      4.5.2 Amplification . . . . . . . . . . . . . . . . . . . . .                                   .   .   .   .   50
  4.6 Down-Conversion and Up-Conversion Stage . . . . . . . .                                        .   .   .   .   51
      4.6.1 Specifications . . . . . . . . . . . . . . . . . . . . .                                  .   .   .   .   52
      4.6.2 Frequency Synthesizer . . . . . . . . . . . . . . . .                                    .   .   .   .   53
             Modulator and Demodulator . . . . . . . . . . . . .                                     .   .   .   .   56
  4.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . .                                .   .   .   .   57

5 RF    FILTERING                                                                                                    59
  5.1   Introduction . . . . . . . . . .   . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   59
  5.2   Overview of Filter Design . .      . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   60
  5.3   Specifications . . . . . . . . .    . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   60
  5.4   Filter Prototype . . . . . . . .   . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   61
  5.5   Filter Implementation . . . .      . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   65
        5.5.1 Overview to Microstrip       Filters   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   65
        5.5.2 Conclusion . . . . . .       . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   72

6 RF   AMPLIFICATION                                                                                                 73
  6.1  Introduction . . . . . . . . . . . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   73
  6.2  Overview . . . . . . . . . . . . . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   73
  6.3  Low Noise Amplifier . . . . . . . .        .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   76
       6.3.1 Specifications . . . . . . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   76
              Design and Implementation          .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   77
   6.4 Power Amplification Stage . . . . .        .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   79
              Design and Implementation          .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   80
   6.5 Conclusion . . . . . . . . . . . . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   82

7 CONSTRUCTION AND TESTING OF THE RECONFIG-
  URABLE RADIO TESTBED                                                         83
  7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
  7.2 Devices and Equipment . . . . . . . . . . . . . . . . . . . . . . . . 84


                                           ii
   7.3   Materials . . . . . . . . . . . . .               .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 85
         7.3.1 Implementation Problems                     .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 86
   7.4   Platform Schematics and Layouts                   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 87
         7.4.1 Baseband board . . . . . .                  .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 87
         7.4.2 Transmitter board . . . .                   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 87
         7.4.3 Receiver . . . . . . . . . .                .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 90
   7.5   Software . . . . . . . . . . . . . .              .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 90
   7.6   Results . . . . . . . . . . . . . . .             .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 97
   7.7   Future Work . . . . . . . . . . . .               .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 98
   7.8   Conclusion . . . . . . . . . . . . .              .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   . 100

8 CONCLUSIONS AND FUTURE WORK                                                 102
  8.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
  8.2 Comparasion with the Universal Radio Peripheral system . . . . . 104
  8.3 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

A ADC Simulations                                                                                                                  107
  A.1 Function ”variance1” . .       .   .   .    .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   107
  A.2 Function ”simple ofdm1”        .   .   .    .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   111
  A.3 Function ”my quantizer”        .   .   .    .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   113
  A.4 Function”ber” . . . . . .      .   .   .    .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   116

B Transmitter and Receiver Drivers                                                                                                 117
  B.1 Transmitter Inicialization . . . . .                 .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   117
  B.2 Receiver Inicialization . . . . . .                  .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   118
  B.3 Common Functions . . . . . . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   118
      B.3.1 Main Function . . . . . .                      .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   118
      B.3.2 Function ”config clk()” . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   119
      B.3.3 Function ”data write” . .                      .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   120
      B.3.4 Function ”enable CE” . .                       .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   122
      B.3.5 Function ”toggle LE” . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   123
      B.3.6 Function ”Toggle sclk” . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   124

C Microstrip Lines Theory                                                                                                          125

D Filters                                                              129
  D.1 Lumped Components Filters Response . . . . . . . . . . . . . . . 129

E Papers                                                                                                                           132

   Bibliography                                                                                                                    136




                                                 iii
List of Figures

 2.1    Superheterodyne Architecture. .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    5
 2.2    IF Sampling Architecture. . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    6
 2.3    Direct Conversion Architecture.       .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    6
 2.4    Low IF Architecture. . . . . . .      .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    7
 2.5    System Requirements Block. . .        .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   13
 2.6    Layered Structure. . . . . . . .      .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   15
 2.7    SDR and Wirelees Evolution. .         .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   18

 3.1    Block Diagram of the Proposed Platform.                       .   .   .   .   .   .   .   .   .   .   .   .   .   23
 3.2    PCS1900 Blocker Specifications [15]. . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   24
 3.3    802.11 Blocker Specifications [15]. . . . . .                  .   .   .   .   .   .   .   .   .   .   .   .   .   24
 3.4    UMTS blocker specifications. . . . . . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   25
 3.5    DCS1800 Blocker Specifications [15]. . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   25
 3.6    Noise networks in the receiver. . . . . . . .                 .   .   .   .   .   .   .   .   .   .   .   .   .   29
 3.7    Flow chart of BB simulation. . . . . . . . .                  .   .   .   .   .   .   .   .   .   .   .   .   .   33
 3.8    Converging Variance. . . . . . . . . . . . .                  .   .   .   .   .   .   .   .   .   .   .   .   .   36
 3.9    BER . . . . . . . . . . . . . . . . . . . . .                 .   .   .   .   .   .   .   .   .   .   .   .   .   37
 3.10   Direct converter receiver requirements. . .                   .   .   .   .   .   .   .   .   .   .   .   .   .   39
 3.11   Block diagram of the system. . . . . . . .                    .   .   .   .   .   .   .   .   .   .   .   .   .   41

 4.1    Block diagram of the system. . . . . . . .                    .   .   .   .   .   .   .   .   .   .   .   .   .   43
 4.2    Time Diagram. . . . . . . . . . . . . . . .                   .   .   .   .   .   .   .   .   .   .   .   .   .   45
 4.3    Comparation of ADC techniques [21]. . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   47
 4.4    ADC Functional Block Diagram [22]. . . .                      .   .   .   .   .   .   .   .   .   .   .   .   .   47
 4.5    DAC Functional Block Diagram [23]. . . .                      .   .   .   .   .   .   .   .   .   .   .   .   .   49
 4.6    Low Pass Filter Frequency Response. . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   50
 4.7    Base Band Amplifier and Low Pass Filter.                       .   .   .   .   .   .   .   .   .   .   .   .   .   51
 4.8    ADF4360 Block Diagram [27]. . . . . . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   54
 4.9    PLL Configuration: Flow Chart . . . . . .                      .   .   .   .   .   .   .   .   .   .   .   .   .   55
 4.10   Demodulator: Block Diagram [28] . . . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   56
 4.11   Modulator: Block Diagram [29] . . . . . .                     .   .   .   .   .   .   .   .   .   .   .   .   .   57

 5.1    Filter Mask. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                          61


                                         iv
5.2  Π Network Prototype. . . . . . . . . . . . . . . . . . . . . . . . .                                                           64
5.3  T Network Prototype . . . . . . . . . . . . . . . . . . . . . . . . .                                                          64
5.4  Bandpass Filter Prototype. . . . . . . . . . . . . . . . . . . . . . .                                                         65
5.5  Field Distribution of a Microstrip Line Section. . . . . . . . . . .                                                           66
5.6  Substrate Parameters. . . . . . . . . . . . . . . . . . . . . . . . .                                                          67
5.7  Coupled Lines Layout. . . . . . . . . . . . . . . . . . . . . . . . .                                                          67
5.8  Hairpin Layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . .                                                        68
5.9  Coupled Line Equivalent Prototype. . . . . . . . . . . . . . . . . .                                                           69
5.10 6th Order Parallel Coupled Line Filter. . . . . . . . . . . . . . . .                                                          70
5.11 6th Order Parallel Coupled Line Filter. . . . . . . . . . . . . . . .                                                          71
5.12 6th Order Hairpin Filter with Passive Network Substituying First
     and Last Sections . . . . . . . . . . . . . . . . . . . . . . . . . . .                                                        71
5.13 6th Order Hairpin Filter: Simulations and Measurements. . . . . .                                                              72
5.14 Implemented Microstrip Filter. . . . . . . . . . . . . . . . . . . .                                                           72

6.1    Matching Networks. .     .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   75
6.2    LNA. . . . . . . . . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   79
6.3    LNA Respond. . . .       .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   79
6.4    Power amplifier. . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   81
6.5    Power amplifier. . . .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   81

7.1    Distortion Sources. . . . . . . . . . . . .                          .   .   .   .   .   .   .   .   .   .   .   .   .   . 86
7.2    Baseband schematic. . . . . . . . . . . .                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 88
7.3    Baseband schematic. . . . . . . . . . . .                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 89
7.4    Baseband Board. . . . . . . . . . . . . .                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 90
7.5    Tx schematic. . . . . . . . . . . . . . . .                          .   .   .   .   .   .   .   .   .   .   .   .   .   . 91
7.6    Tx schematic. . . . . . . . . . . . . . . .                          .   .   .   .   .   .   .   .   .   .   .   .   .   . 92
7.7    Top Tx Board. . . . . . . . . . . . . . .                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 92
7.8    Rx schematic . . . . . . . . . . . . . . .                           .   .   .   .   .   .   .   .   .   .   .   .   .   . 93
7.9    Rx schematic . . . . . . . . . . . . . . .                           .   .   .   .   .   .   .   .   .   .   .   .   .   . 94
7.10   Rx schematic . . . . . . . . . . . . . . .                           .   .   .   .   .   .   .   .   .   .   .   .   .   . 95
7.11   Top Rx Board. . . . . . . . . . . . . . .                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 95
7.12   Software Stacks. . . . . . . . . . . . . . .                         .   .   .   .   .   .   .   .   .   .   .   .   .   . 97
7.13   Matlab implementation. . . . . . . . . .                             .   .   .   .   .   .   .   .   .   .   .   .   .   . 98
7.14   Constellation for a BPSK received signal.                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 98
7.15   Constellation for a QPSK received signal.                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 99
7.16   Eye diagram for a BPSK received signal.                              .   .   .   .   .   .   .   .   .   .   .   .   .   . 99
7.17   Received Signal in the Oscilloscope. . . .                           .   .   .   .   .   .   .   .   .   .   .   .   .   . 100
7.18   SDR Platform. . . . . . . . . . . . . . .                            .   .   .   .   .   .   .   .   .   .   .   .   .   . 100

D.1 Bessel schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . 129


                                                    v
D.2   Bessel Filter Response.   .   .   .   .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   130
D.3   Max Flat schematic. .     .   .   .   .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   130
D.4   Max Flat Response. . .    .   .   .   .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   130
D.5   Gaussian LC Filter. . .   .   .   .   .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   131
D.6   Gaussian Response. . .    .   .   .   .    .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   131




                                                vi
List of Tables

 2.1   Wireless evolution [11]. . . . . . . . . . . . . . . . . . . . . . . . .                           16

 3.1   Digital Cellular Telephones Specifications     [5]. .   .   .   .   .   .   .   .   .   .   .   .   21
 3.2   Wireless Specifications [5]. . . . . . . . .   . . .    .   .   .   .   .   .   .   .   .   .   .   22
 3.3   Radio Performance Specifictions . . . . .      . . .    .   .   .   .   .   .   .   .   .   .   .   23
 3.4   Simulation Parameters. . . . . . . . . . .    . . .    .   .   .   .   .   .   .   .   .   .   .   34
 3.5   Specifications . . . . . . . . . . . . . . .   . . .    .   .   .   .   .   .   .   .   .   .   .   40

 4.1   Mixers Characteristics [26] . . . . . . . . . . . . . . . . . . . . . .                            52

 7.1   Commercial devices used . . . . . . . . . . . . . . . . . . . . . . .                              84
 7.2   Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . .                            97

 8.1   USRP and SDR Platform Comparasion. . . . . . . . . . . . . . . 105




                                       vii
Abstract

Wireless communications is a technology in continuous evolution, introducing

new services and applications techniques which permit dynamic spectrum alloca-
tion. Communication devices will need to support several protocols at different

frequencies. The hardware required for this ability will need to move seamlessly

between these protocols and frequencies without interruption to the communi-

cation session. One such technology capable of meeting these requirements is
software defined radio. This thesis describes the features and capabilities of the
reconfigurable radio platform which was developed in the Institute of Microelec-

tronic and Wireless Systems (IMWS), Maynooth as part of the CTVR effort in
cognitive radio systems.


The platform is designed to operate in a frequency band from 1.6GHz to 2.5GHz

and support the DCS1800, PCS 1900, UMTS-FDD, UMTS-TDD and 802.11b

standards. However, since two test licenses of 25 MHz have been provided by

COMREG (the Irish telecommunications regulator) to the CTVR (Centre for

Telecommunications Value-Chain Research) for use by its member institutions at
the center frequencies of 2.085GHz and 2.35GHz, these have been used as testing

frequencies during the development of the platform.


Of the supported standards GSM is the most difficult to meet. For this rea-

son the specifications for the receiver and transmitter are taken from the 2nd
generation of standards. These are a phase-noise of -152dBc/Hz and sensitiv-



                                      viii
ity of -107dBm, with an out-of-band blocker of 0dBm. 30dBm is the maximum

peak-power output. Both transmitter and receiver have a maximum bandwidth
of 22MHz.



Both transmitter and receiver are implemented using a direct conversion archi-
tecture, chosen due to its low power dissipation, simpler design and easier tuning

across large frequency bands. As many off-the-shelf parts as possible have been

used for the implementation of the software defined radio. This permits the de-

velopment of the platform in a short space of time. However the specifications

of the commercially available parts do not meet the full requirements for the
platform. To address this some of the parts will be replaced by custom silicon

designs developed in the IMWS to improve performance. The platform consists
of a USB interface to standard PC, ADC and DAC, direct conversion transmitter
and receiver. The analog to digital conversion and digital to analog conversion

have a large influence on the performance of the platform. Consequently simula-
tions using Matlab have been carried out to calculate number of bits needed to
meet the SNR (Signal to noise ratio) requirements. A USB driver is implemented
to control sampling rate, chip enables, frequency selection and timing functions

across the entire platform. A USB interface chip is used operating up to 480Mbps.

It features the 8051 micro-controller which is programmed in C to provide control
signals for the rest of devices in the system such as: demodulator, PLL, ADCs,

DACs, modulator, gain control amplifiers and channel selected filters.




                                        ix
Acknowledgements

First I would like to thank to my direct Master supervisor Gerard Baldwin, who

has been actively involved in many aspect of this thesis, and he helped me with
the developement of this project. Second, I would like to thank to Doctor Ro-

nan Farrell who supported this project and to many others who have aided this

research.



I am particulary grateful to Barbara Walsh because without her support I
wouldn’t have reached the end of this thesis. I especially appreciate her help

from the first day that I arrived to Ireland. Finally, I want to thank to all my
collegues from the Institute of Microelectronic and Wireless Systems for their
support and for their contributions to this work.




                                       x
Chapter 1

INTRODUCTION


1.1     Motivation

Analog radio systems are gradually becoming obsolete. Wireless communica-
tions technologies are constantly evolving, characterized by things like: multiple

and evolving standards, different types of equipment for subscribers, different
transmission environments. The wireless industry is changing as the result of
the continuous convergence of the mobile and internet market. This market de-

mands inexpensive hardware, flexibility and easly implemented systems. These

requirements necessitate the development and implementation of a new and flex-
ible technology which meets the existing requirements of 2nd and 3rd generation
of mobile telecommunications and future standards that may emerge. Reconfig-

urable radio or SDR (Software Defined Radio) is one proposed solution to fulfil

these demands. Subscribers, network operators, service providers and equipment

manufacturers have different motivations and expectations from new technologies.

SDR is of interest as it has the potential to meet their different requirements.



This thesis presents a software defined radio platform that will allow SDR tech-

niques ti be demonstrated. It is the first generation of a reconfigurable radio

technology implementation. As a first step, the hardware platform uses only
components that are currently available on the market.

                                        1
1.2     Contributions of this work

This work aims to construct the communications standards compliant for SDR,

from commercially available components. In doing so, it explores the capabilities
of commercial components and systems to meet the demands of SDR. Addition-
ally, this works highlights the areas on which not suitable parts are available. It

also provides a platform for experimental software development and applications
of SDR such as dynamic spectrum allocation and cognitive radio.



1.3     Organization of Thesis

Following this introductory chapter, Chapter 2 contains a background in recon-

figurable radio; development, available system architectures for this technology,

advantages and features. Chapter 3 introduces the chosen platform giving spe-
cific details about covered standards and requirements. Chapter 4 presents the
characteristics and qualities of the platform, paying particular attention to the

baseband part. Chapter 5 and 6 detail the radio frequency, RF, sections (filtering
and amplification), presenting the design steps. Finally chapter 7 introduces the
physical platform implementation, with the results and conclusions of the work.
The appendix contains details of the simulations functions, some of the code to

drive the software part of the platform, and theory details about microstrip lines.




                                        2
Chapter 2

RADIO SYSTEMS


2.1     Introduction

In this chapter the evolution of digital communications radio systems is presented
from its inception at the beginning of the last to modern day implementations

using such technology as software defined radio, SDR. Various architectures are
presented along with their advantages and disadvantages, culminating in the out-
lining of the SDR system. Finally, some of the modern day standards are pre-

sented in order to explain the necessary specifications and requirements for an

SDR implementation.



2.2     Evolution of Radio System

Radio is derived from the term electromagnetic radiation which is the basis of

radio waves. Radio waves are electromagnetic signals which are propagated in
straight lines. The need to send signals over water without any wires led to the

discovery of radio telecommunications. In this thesis radio signal are referred
as microwave signals with frequencies between 300MHz and 300GHz. It is a

concept which involves transmission and reception environments where waves are

air-interface propagated in different frequency bands. The propagation character-

istics of these environments depend on several factors such as: location (latitude


                                        3
and altitude), zone (mountain, urban, water etc), weather, movement, frequency

of communication and so forth. For this reason many different radio hardware
architectures have been developed according to the particular radio environment
and data transmission requirements. Consequently the choice of a particular RF,

Radio Frequency, and architecture will impact the performance of this system.


2.2.1    Early Beginnings

The first experiments in radio transmission are commonly held to have been car-

ried out by Marconi in an attempt to communicate across the Atlantic Ocean

without the use of wires. He developed a crude spark gap transmitter with which
he carried out the first transatlantic transmissions in 1901. This demonstrated
the future potential of radio communications and the area quickly developed.



One of the first truly electronic radio receiver architectures was the Tuned Radio
Frequency (TRF) architecture patented by Ernst Alexanderson in 1916 [1]. This
architecture was composed of various tuned radio frequency amplifiers. Each
stage is tuned to the transmitted frequency [1]. The final demodulation was done

by an envelope detector. This was basically an AM, amplitude modulation, sys-

tem with the same principles as modern day homodyne architectures. However
such receivers had problems associated with oscillations due to the interelectrode
capacitance of the electronic valves used to implement them.


2.2.2    Superheterodyne Architecture

In order to solve the issues caused by the previous architecture, Edwin Armstrong

invented the superheterodyne architecture in 1918 [1]. This was a new departure
from existing architectures. Instead of carrying out all the amplification and

filtering at the carrier frequency, Amstrong used multiple stages at different fre-

quencies. In doing so, he avoided issues with oscillations generated by coupling
from individual stages.


                                        4
To this day this architecture is still in common use, and can be found in many

modern mobile phone base stations both in transmission and reception.


Even though widely used it is difficult to change system parameters such as

bandwidth due to the requirements for multiple filters at radio and intermediate

frequencies, due to the need to reject image signals and local oscillator signals.

In modern digital communications implementations of this, the analog to digi-

tal conversion is performed at baseband after the double down conversion stage,
which transforms the signal from RF frequencies to baseband. In this architec-

ture the final IF stage is carried out at a fixed frequency allowing the construction
of a high performance filter and local oscillator, thus significantly improving the
performance of the overall system. This gives high selectivity at the expense of

narrowband operation and high complexity [3]. Figure 2.1 illustrates a simple
configuration of this receiver.




                   Figure 2.1: Superheterodyne Architecture.




2.2.3    IF Sampling Architecture

A modern day development of the super heterodyne architecture is IF sampling.

In this architecture the final down conversion of the signal from IF to baseband
is done digitally. An ADC is placed at the IF stage. Subampling is necessary

to sample bandpass IF signals. This architecture is becoming more popular in
modern receiver designs. IF sampling is an appropriate architecture to deal with

wide bandwidth signal and multicarrier systems. The problem with this particular

                                        5
architecture is that high frequency components in the signal can be aliased into

the band of interest. To solve this issue anti-aliasing filters are required increasing
the complexity of the system. Moreover this architecture requires high speed and
high resolution ADCs which consume more power. Figure 2.2 illustrates the radio

receiver for this architecture.




                      Figure 2.2: IF Sampling Architecture.




2.2.4     Direct Conversion Architecture

Direct Conversion Architecture is the modern day successor to the tuned radio

frequency architecture and has similarities to the earliest tuned receivers. The
RF signal is directly converted to baseband using a local oscillator at the same
frequency as the carrier signal, without any intermediate stage, and the resultant

problems with images [3]. This reduces filter requirements for this architecture.
However a DC offset can be generated due to any frequency error in the local
oscillator. This architecture can have a complex baseband signal for particu-
lar modulation schemes, special attention must be paid to the generation of the

quadrature local oscillation signal. Any error in the quadrature phase differ-

ence results in inband mirrored images corrupting the wanted signal. Figure 2.3

illustrates the configuration of the radio receiver for this architecture.




                   Figure 2.3: Direct Conversion Architecture.



                                          6
2.2.5    Near-Zero-IF or Low IF Architecture

This is a practical attempt to combine the advantages of the superheterodyne

architecture with the advantages of the direct conversion architecture. Here the
signal is downconverted to near-zero IF using a standard heterodyne architecture.
This is subsequently sampled digitally at the Nyquist sampling rate. Generally

the sampling frequency is not more than twice the bandwidth of the baseband

signal plus some guard band for non-ideal sampling . This architecture does not

need to deal with DC offset problems as the signal is not at zero frequency so any

DC component from the RF circuit is not mixed with the direct converted de-
modulated signal. However it has the drawback that better image rejection filters
are required. Also the low IF frequency selected may fall within the flicker noise

region of the semiconductor process used to implement it. Figure 2.4 illustrates
the radio receiver configuration for this architecture.




                        Figure 2.4: Low IF Architecture.




2.2.6    Software Defined Radio

SDR has many meanings within the industry, but for the purposes of this thesis
the Federal Communication Commissions, FCC, definition is as follows [4].



FCC definition:”An SDR is a radio that includes a transmitter in which the

operating parameters of the transmitter including frequency range, modulation
type or maximum output power (either radiated or conduced) can be altered by

making a change in software without making any change to hardware components

that affect the radio frequency emissions”.


                                        7
However aspirations and reality are different concepts. This can be implemented
in many ways. For example, one implementation could consist of an antenna

followed by the ADC/DAC. All signal processing is carried out in the digital
domain using software. The antenna remains the only analog stage in the sys-

tem. This is considering the SDR definition given by Joseph Mitola in 1991,

where the 8% of the functionality of the system is provided in software. However

suitable ADCs/DACs with the required resolution, speed, sensitivity and power
efficiency do not yet exist to implement such a system. On the other hand, the

pragmatic SDR is defined as a system where reconfigurability is added where it is

economically appropriate. In general this approach can utilize one or more of the
hardware architectures already outlined. This implementation is the more realis-
tic approach and is the one taken here. This approach uses hardware which can be
reconfigured by software. Depending on the down and up-converting stages, SDR

can be implemented by a superheterodyne, a direct conversion, an IF sampling or
a near zero architecture approach. The choice of a particular architecture for the
signal conversion is related to the utility and the reconfigurability requirements
of the system. To provide an overview of SDR, a discussion in the historical

evolution of SDR is presented next.


SDR Evolution

Historically, implementations of SDR have existed since the ’70’s, though at very
low frequencies in defence applications and with analog base stations. For mo-

bile telephony in the early ’80’s base stations started to be built around digital

hardware. Later, in the ’90’s SDR continued in development, in particular in
military interoperability endeavours. However commercial applications of SDR

were neither practical nor cost effective until the late 90’s. In the past few years,
important advances in A/D converters, DACs, RF technology and processing

hardware have allowed SDR to be considered from the commercial perspective [5].



                                         8
The development of wireless networks in recent years (interoperability, better
signal propagation, better noise figure, etc) has helped the evolution of improved

SDR technology. The explosive growth of communications standards has ne-
cessitated the development of technology which can be quickly adapted to new

standards. SDR is one such technology. In the future SDR will be used to cover

the capabilities and services of all generations of wireless communications stan-

dards. The evolution of SDR is described as follows.

  1. The First generation—Modal SDR: The first generation of SDR sys-

     tems were not fully reconfigurable. Instead they generally consisted of sev-
     eral separate radio implementations tied together at baseband [6]. An ex-

     ample of this kind of SDR system is a dual-mode cell phone which consists
     of two hardware radios , each one supporting a different telecommunica-
     tion standard. However the user is limited to only two modes because the

     phone allows switching just between the two modes built into the radio,

     without the ability to upgrade the system with new waveforms or use new
     frequencies [5]. All subsequent processing of the signals is done in software.

  2. Second generation of SDR—Reconfigurable SDR: Reconfigurable
     SDR is a radio which can be upgraded by software. It involves technologies

     such as Digital Signal Processing (DSP), Application-Specific Integrated

     circuit (ASICs) and Field Programmable gate arrays (FPGAs). This gen-
     eration included more flexibility but a limited adaptability since reconfig-

     uration is not realized in the totality of the system. This was achieved at

     the expense of high hardware costs. As a result this was used for military
     applications. The main problem is that the investment for these systems is

     high and they become obsolete very quickly [5].

  3. The final target—Pure Software Radio: This generation will have a
     totally digital hardware part up to the antenna [6]. This is still an un-


                                        9
      reached target in need of further study. Suitable ADCs/DACs are not

      available. In this generation the system hardware is completely flexible and
      reconfigurable. It maximizes software reuse across platforms and software
      generations. It runs on top of a standard operating system (OS) whether

      on general purpose (GP), central processing units (CPUs), digital signal
      processing (DSPs), or other processing engines [5].


Advantages and Drawbacks of Software Defined Radio

The principal advantage of SDR is the ability to adapt to new standards and

applications, without the need for hardware modifications. This has the knock-om

affect of enabling technologies like dynamic spectrum allocation, which produces
an improvement in spectral efficiency. A good SDR implementation can operate
over a large range of frequencies with channels of varying bandwidth and varying

modulation schemes. SDR brings advantages to many different users of wireless

communication systems. The advantages of SDR for some of these users are listed
as follows:

   1. For mobile network operators: The introduction of a higher level of
      flexibility reduces the cost of network roll-out.

   2. For subscribers: The ability to change between standards permits an
      easier international roaming and increased personalization. SDR features
      flexibility to add new functionality such as new 4G standards to existing

      phones.

   3. For handset and base station manufacturers: Since one unit can

      be used across multiple standards, capital cost decreases and production

      flexibility increases. This produces new economies of scale. Because SDR
      replaces multiple hardware radios in a single hardware platform a greater

      economy is achieved.




                                        10
  4. For regulators: SDR enables dynamic spectrum allocation, which in-

     creases the ability of the regulator to utilize the spectrum efficiently.

SDR has some drawbacks such as: higher power consumption, higher processing

power requirement and higher initial cost. Since the SDR approach involves high

speed and high resolution ADCs, from a power and cost point of view the design

may not be the best solution in some situations [7].


Applications of Software Defined Radio

SDR is used to provide wireless communication capabilities for many different
applications, both within the field of telecommunications and other such diverse

fields as medical devices [8]. Some of them are described below:

  1. Emergency Services Communications: SDR is finding important use
     in the filed of first response emergency service communications. The flexi-

     bility of SDR allows the implementation of radio systems that can commu-
     nicate between the many disparate radio systems in use by the emergency

     services such as the police, ambulance service, and fire brigade.

  2. Surveillance of Radio Systems: The capability of SDR to operate across

     a wide range of frequencies and bandwidths, together with the ability to im-
     plement new modulations schemes makes it an ideal tool for the surveillance
     of new and existing standards.

  3. Broadcasting: Due to the proliferation of new standards in broadcasting

     (radio and television), new developed product using a particular architec-

     ture must be upgraded. SDR has the adaptability and flexibility to achieve

     this [8].

  4. Medical equipment: SDR enables new functions and updates to be added

     quickly and easily. It provides huge scope for product differentiation.

  5. Dynamic Spectrum Allocation, DSA: The allocation of frequency spec-

     trum internationally is regulated by the International Telecommunication

                                       11
     Union (ITU). For this purpose the world is divided in three regions ac-

     cording to their geographical features [9]. Region 1 takes Europe, Africa,
     part of Asia. Region 2 covers America, Greenland, part of the Atlantic
     Ocean and the North Pacific Ocean. Region 3 covers The Pacific Islands,

     Australia, India, China, the Indian Ocean and the South Pacific Ocean.
     However the allocation band plan is independently regulated by govern-

     ments in most countries, often with different frequency band allocations for

     different applications. This method of frequency allocation is inefficient. A

     more efficient mechanism is dynamic spectrum allocation (DSA). The main

     principle of DSA is the use of unused spectrum, increasing the utilization
     of the spectrum [9].


     Depending on the purpose, the definition of the parameters according to
     the spectrum may vary. Designers and regulators have two different points

     of view regarding the use of spectrum. The constraints imposed by the
     regulators for the use of the spectrum limit the possibilities for designers
     to improve access to the spectrum. In order to adapt to the limitations
     of both purposes an adaptable system is necessary. Thus SDR is a pro-

     posed technology to adapt to these limitations. SDR can ensure that other

     users are not affected by the adaptative system. Adaptability in Spectrum
     allocation or dynamic spectrum allocation has been developed in systems

     that use unlicensed bands such as cordless phones or Enhanced Data Rates

     Evolution (EDGE) for global systems for mobile communications (GSM).


Technology Structure

The implementation of a SDR system gets more complicated since the main

requirement is adaptability. FigureFigure 2.5 illustrate the features needed for a
SDR system, these are described below:

  1. Digital Signal Processing


                                       12
       ADC and DAC : Analog to Digital and Digital to Analog conversions

           with increased resolution and sampling rate.

       ASIC : Application-Specific Integrated Circuit with lower power and
           greater processing. However it does not permit programmability.

       DSP, FPGA and micro-processors: Digital Signal Processing, Field
           Programmable Gate Array and micro-processors with lower power and

           programmability.

  2. Radio Frequency Devices:

       Antennas: Antenna arrays permits the use of adaptive techniques, which

           provide capabilities such as interference cancellation.

       PA, LNA: Power amplifiers and low noise amplifiers work with an in-
           creased bandwidth while keeping the same gain characteristics.

       Filters: They have an increased bandwidth but limited broadband capa-
           bilities.




                       Figure 2.5: System Requirements Block.


For a better comprehension of SDR performance a very simple layered structure

of a reconfigurable system is introduced below. The system is divided in five
layers: the application layer (on the top of the system); the interface layer;


                                        13
the configuration layer; the digital signal processing (DSP); and the radio fre-

quency (RF) layer at the bottom of the system.


Application layer : This level of the system corresponds to the user level,

which is responsible for the transmission and reception of data.



Interface layer : This level is responsible for interfacing the top layer or appli-

cation level and the radio hardware. It controls the information coming in and

going out of the radio, and packaging the incoming information before sending it

to the application layer. This layer containts the code for the algorithms that are
going to be used and their possible sequences of interconnection.


Some of the most important and significant parameters for the system like signal
and sampling rates have to be taking into consideration at this particular level.

As an example, the connection between USB 2.0 and the DSP layer, different
signal rates between both levels can generate problematic consequences on the
whole system performance.


Configuration layer : This layer controls the reconfiguration of the hardware.

It set up the various hardware elements according to the programming packets

sent by the interface layer.


Digital Signal Processing layer : This layer performs the actual operation

on the data to implement the functionality of the radio. At this level analog-to-

digital and digital-to-analog conversion take place. This level is highly dependent
on the previous level, because of the relationship between the sampling rate, num-

ber of quantization bits and the signal to noise ratio (SNR).


RF layer : At this level the signal is received or transmitted, up or down-



                                        14
                          Figure 2.6: Layered Structure.


converted, amplified and filtered. Noise figure, power consumption and frequency
adaptability of the devices are the most important things to take in consideration
at this layer.



2.3      Wireless Standard Evolution

SDR, must meet a wide range of requirements for wireless communications stan-

dards. This section details the evolution of wireless standards for cellular mobile
telephony and their principal characteristics.



First Generation, 1G
This generation was mostly developed in the 1980s. It uses frequency division

multiple access (FDMA) techniques and analog voice coding [12]. Several exam-

ples of 1G systems are:



                                        15
                         Table 2.1: Wireless evolution [11].

  1. Advance Mobile Phone Services, AMPS: It uses 20 MHz band centred

     around 800 MHz. It was deployed in Japan (1979) and United States
     (1983) [12].

  2. Nordic Mobile Telephone, NMT: Launched in 1981, cover Sweden, Norway,

     Demark and Finland. It uses a band centred et 900 MHz, but it is not
     longer used [12].

  3. Total Access Communication System, TACS: It was initially deployed in

     1985. Similar design to AMPS and is still in use in some parts of Europe [12].

Second Generation, 2G
This generation supports digitally encoded voice, limited data communication and

different levels of encryption. It uses time division multiple access (TDMA) tech-

niques, and in some cases code division multiple access (CDMA). It uses digital
data transmission. The capacity is increased using dynamic speech compression

techniques [11]. Second generation systems that were developed include:

  1. IS-54, IS-136: American digital cellular standards. Based on TDMA tech-

     niques.

                                         16
  2. Integral Digital Enhaced Network, iDEN: Motorola proprietary system cen-

      tred at 800 MHz (private mobile radio spectrum). It uses TDMA tech-
      niques.

  3. Digital European Cordless Telephony, DECT: Based on TDMA techniques.

      It has the highest data rate (1,728kps) of all TDMA digital cellular systems.
      It is used for cordless phone at home.

  4. Global System for Mobile, GSM: It was launched in 1991. It is based on
      TDMA techniques with a band at 900 MHz, which has been extended with

      a second band at 1800 MHz. It is the dominant world standard today.

Second Generation Towards Third Generation, 2.5G
This generation extends 2G systems, adding packet-switched connection and en-
hanced data rates. This generation set of standard, that led to, is composed
by:

  1. IS95, CDMAone: Based on CDMA techniques, all user share the same
      frequency. It is the first step for the 3G [12].

  2. General Packet Radio Services, GPRS: It provides moderate speed data
      (38-40kbps). GPRS is a method to enhanced 2G phones. It used circuit

      switched data (CSD) to transfer data. This is a big steps towards 3G [12].

  3. Enhanced Data Rate for GSM Evolution, EDGE: This technology is an

      evolution of GPRS towards 3G standards. It is compatible with other

      TDMA systems and can be used for any packet switch applications.

Third Generation, 3G
This generation provides universal roaming and an increased capacity [11]. All

3G standards are based on the CDMA technique. It provides hight data rates,

thus adding the capability to transmit data and video as well as voice. Some of

the 3G standards are specified below [1].



                                         17
  1. Universal Mobile Telecommunications System, UMTS: It is based on wide-

     band code division multiple access, WCDMA. It is standardized by the
     3rd generation partnership project, 3GPP. The specifications are based on
     evolved global standard mobile specifications.

  2. High Speed Downlink Packet Access, HSDPA: It is an evolved UMTS, pro-
     viding 1.8 Mbps or 3.6 Mbps. in down-link.

  3. High Speed Uplink Packet Access, HSUPA: Equally with HSDPA it is an

     evolved UMTS, providing 5.76 Mbps in up-link.

  4. Time Division-Synchronous Code Division Multiple Access, TD-SCDMA: It

     dynamically adjusts the number of time slots used for uplink and downlink.
     The spectrum allocation flexibility increases since it does not required paired
     spectrum for downlink and uplink. It is used mostly in China.

  5. CDMA2000: It constitutes UMTS’s principal competitor. It uses multi-
     carrier synchronous CDMA techniques and provides 3.75Mhz bandwidth.




                   Figure 2.7: SDR and Wirelees Evolution.


Four Generation, 4G

This generation, according to the wireless world research forum (WWRF) is a

                                       18
network that operates in internet technology and runs at speeds from 100Mbps

to 1Gbps. 4G terminals will have all the standards from 2G to 3G implemented.
According to the European Commission, 4G will ensure service across a variety
of wireless systems and networks. It will provide an optimum delivery via the

most appropiate network available [2]. Some of the additional standards for 4G
are described below [1].

  1. Worwilde Interoperability for Microwave Access,WiMax IEEE802.16: It
      provides high speed mobile data and telecommunications services. It works

      on the spectrum band from 10 GHz to 66 GHz. It uses orthogonal frequency

      division multiplexing, OFDM.

  2. Wireless Broadband, WiBro: Wireless broadband internet technology, it is
      merged into WiMax and uses OFDM and 8.75 MHz of channel bandwidth.

      It is intended for portable internet usage.

  3. LTE: Long Term Evolution. It is a new envolved release of the UMTS

      standard. It is an upgraded UMTS with a simplified architecture to an

      all-IP system [1].



2.4      Conclusion

This chapter has presented the evolution of radio systems towards software de-

fined radio, SDR. It has particularly described the advantages and applications

of SDR in the modern days. Flexibility and adaptability are two important qual-
ities of SDR derived from this chapter. A background of standard evolutions

toward SDR has been described. Concluding with SDR as a technology capable

of covering a wide range of wireless telecommunications standard due to its high
level of flexibility. This chapter has been a basic introduction to SDR to continue

more in detail in next chapter, which will introduce some of the qualities and

requirements demanded in a SDR platform.



                                        19
Chapter 3

REQUIREMENTS AND
SPECIFICATIONS


3.1     Introduction

In this chapter transmitter and receiver requirements for various communication
standards are presented. These will be used to develop the requirements for the

SDR platform. The ADCs are simulated in order to specify their performance
for the platform.



3.2     Standard Specifications

The necessary requirements for each standard are presented in this section.
With the development of a reconfigurable radio platform as a target, a range of

standards have been taken into consideration in order to create the necessary
specification for this system.



The ideal approach would be the implementation of all the wireless standards
together: GSM, CDMA2000, UMTS, IEEE802.11x, IEEE802.16x, IEEE802.15x,

and IEEE 802.20x, Bluetooth and UWB. However the incompatibility between

air interfaces used by each standard is an issue. For this reason the standards are

                                        20
            Table 3.1: Digital Cellular Telephones Specifications [5].


be divided into different groups with similar characteristics [13] such as: symbol
rate; power; and range, according to Tables 3.1 and 3.2. These groups are
described below:

IEEE802.15.4a and Bluetooth: low rate (<1Mbit/s), short range (around

10m), and transmitted power less than 1mW.


IEEE802.15x and UWB: high rate (up to 500Mbits/s), short range (around

10m), low transmitted powers.


IEEE802.11x, IEEE802.16x, IEEE802.20x and 2G/3G mobile: lower

rates, higher powers, several bit rates. The common feature of this group of

standards is that at a fixed frequency with a range of bit rates they deliver ser-

vices to the end user over longer distances.




                                        21
                     Table 3.2: Wireless Specifications [5].


Since the last group of standards is the most demanding, this platform is fo-
cused to meet as many requirements as possible for these standards. As DCS
and PCS share a band with the European 3G standards, these along with the

two bands within GSM as well as the 802.11 and 802.16 bands are of interest for

the platform. with the functionality of a local area Network (LAN) is difficult
to achieve. The physical layer radio performance specifications of this group are

described in Table 3.3.



3.3     System Specifications

The proposed platform is designed to operate in a frequency band from 1.6GHz
to 2.5GHz and support the DCS1800, PCS 1900, UMTS-FDD, UMTS-TDD and

802.11b standards. Of the supported standards DCS1800 is the most difficult to

                                      22
                  Table 3.3: Radio Performance Specifictions


meet. For this reason the signal specifications for the receiver and transmitter
are taken from DCS1800. Both transmitter and receiver are implemented using
direct conversion architecture, chosen due to its low power dissipation, simpler
design and easier tuning across large frequency bands. As many off-the-shelf parts

as possible are used for the implementation of the software defined radio. The

platform is separated in three main blocks: receiver, transmitter and baseband
board. The proposed blocks for the design are shown in Figure 3.1.




             Figure 3.1: Block Diagram of the Proposed Platform.




3.3.1    Radio Frequency Specifications

Receiver Specifications

The purpose of a RF receiver is to filter the received radio frequency signal and

convert it to baseband by mixing the signal with local oscillator. Some of the

                                       23
most important parameters of interest at the receiver are: sensitivity, selectivity,

Noise Figure and third order intermodulation products [14]. These parameters
are decided by the BER and blocker performances of the system.

  1. Selectivity and Blocker Specifications

     Selectivity is the ability of the receiver to reject nearby signals outside of
     the desired band and respond only to the required transmission. Some of

     the causes of selectivity degradation in the receiver are the spurious signals
     generated by adjacent channels [15]. The blocking performance specifies

     the overall selectivity. Thus, the blocker specifications for the group of

     standards covered by this platform are illustrated in Figure 3.2 to Figure 3.5.
     Of these, the most difficult to achieve is DCS1800.




             Figure 3.2: PCS1900 Blocker Specifications [15].

                                                 Inband IEEE 802.11b

                  −43dBm                                                             −43dBm
                111
                000
                111
                000                                                       1111
                                                                          0000
                000
                111                                                 0000
                                                                    1111  0000
                                                                          1111
                000
                111                −73dBm              f       −73dBm
                                                                          0000
                                                                          1111
                111
                000
                                                           0

                111
                000                                                       0000
                                                                          1111
                000
                111                                                       1111
                                                                          0000
                                                                          1111
                                                                          0000
                000
                111                                                       0000
                                                                          1111
                111
                000
                000
                111                                                       1111
                                                                          0000
                111
                000                                                       1111
                                                                          0000
                111
                000                                                       1111
                                                                          0000
                                                                               f
                                      f −11MHz




                                                               f +11MHz
                             f




                                                                          0 +33MHz
                                       0




                                                                0
                        0 −33MHz




               Figure 3.3: 802.11 Blocker Specifications [15].



                                                       24
                                                           UTMS−FDD                                                                                                                             UTMS−TDD



−15dBm                                                                                                                             −15dBm


−30dBm                                                                                                                             −30dBm


−44dBm                                                                                                                             −44dBm
                                                              In−band                                                                                                                 In−band                                In−band
  Power




                                                                                                                                     Power
          1MHz


                 2025MHz


                                      2050MHz


                                                 2095MHz




                                                                          2185MHz


                                                                                    2230MHz


                                                                                                         2255MHz


                                                                                                                   12750MHz




                                                                                                                                              1MHz


                                                                                                                                                     1,815MHz




                                                                                                                                                                                                                                                                            12750MHz
                                                                                                                                                                 1840MHz


                                                                                                                                                                           1885MHz




                                                                                                                                                                                                 1920MHz


                                                                                                                                                                                                                   2000MHZ




                                                                                                                                                                                                                                           2055MHz


                                                                                                                                                                                                                                                     2095MHz

                                                                                                                                                                                                                                                                  2120MHz
−44dBm                                                                                                                             −44dBm
                                                                f                                                                                                                                          f
                                                                    0                                                                                                                                          0
−56dBm                                                                                                                             −56dBm
  Power




                                                                                                                                      Power
                           f −15MHz




                                                                                                                                                                f −15MHz
                                                f −10MHz




                                                                         f +10MHz




                                                                                              f +15MHz




                                                                                                                                                                                     f −10MHz




                                                                                                                                                                                                                                f +10MHz




                                                                                                                                                                                                                                                       f +15MHz
                            0




                                                                                                                                                                 0
                                                 0




                                                                          0




                                                                                               0




                                                                                                                                                                                      0




                                                                                                                                                                                                                                 0




                                                                                                                                                                                                                                                        0
                                                             Frequency                                                                                                                           Frequency


                                                           Figure 3.4: UMTS blocker specifications.




                                          Figure 3.5: DCS1800 Blocker Specifications [15].


     2. Receiver Sensitivity

          This is the minimum signal power delivered to the input terminal of the

          receiver for which the required BER is met for the particular radio system.
          The BER value for acceptable performance in voice systems is generally

          defined to be 10−3 , however this depends on the used standard [14]. The


                                                                                                                              25
  sensitivity can be calculated from the total noise figure and the noise floor

  at the input of the receiver using equation(3.1)


      Sensitivity(dBm) = N Ftotal (dB) + CN Routput (dB) + N F loor         (3.1)


  The reference sensitivity levels for the covered standards are given below:

   (a) Sensitivity(DCS−1800) = -102dBm @SNR=9dB

   (b) Sensitivity(P CS−1900) = -102dBm @SNR=9dB

   (c) Sensitivity(U M T S−F DD) = -107dBm @SNR=18.9dB

   (d) Sensitivity(U M T S−T DD) = -105dBm @SNR=6dB

   (e) Sensitivity(802.11) = -76.5dBm @SNR=10dB

  Of these the sensitivity requirements for UMTS-FDD is the lowest at -
  107dBm, thus this is required sensitivity for this system.

3. Intermodulation Nonlinearities
  This is the tendency for modulation products generated by devices with non

  ideal characteristics, to lie in the band of interest. In a zero-IF architecture

  this parameter is carefully considered since these unwanted signals lie in the

  down-converted signal band and corrupt the wanted signal. The standard
  model for it includes a third order term to model the nonlinearities. The

  products contributed by this third order term appear at 2w1 − w2 and
  2w2 − w1, where w1 and w2 are the frequency of the wanted signal and

  an adjacent channel signal respectively [16]. As the input power increases

  the third order intermodulation products increase producing distortion in
  the desired signal. IIP3 (input third order intercept point) is a measure

  the linearity of the system. The overall required system IIP3 is calculated

  using the following approximation:

                                                ∆P
                                IIP 3 = Pin +                               (3.2)
                                                 2

                                     26
  where Pin is the power of the interference and ∆P is the increment between

  the desired power and the interference power.
  For m-stages the IIP3 can be obtained as follows:

                                              2            2 2
                     1          1            α1           α1 β1
                          =            +             +          + ···     (3.3)
                   A2 3
                    IIP       A2 3,1
                               IIP          A2 3,2
                                             IIP         A2 3,1
                                                          IIP



  where α1 and α3 are the first and third order gain of the first stage and

  β1 is the first order gain of the second stage and so for. A2 3 is the third
                                                             IIP

  order intercept point and is given by:

                                               4 α1
                                 AIIP 3 =       | |                       (3.4)
                                               3 α3

  The IIP3 requirement for the covered standards are:

   (a) IIP 3(DCS−1800) = -18dBm

   (b) IIP 3(P CS−1900) = -18dBm

   (c) IIP 3(U M T S−F DD) = -21.3dBm

   (d) IIP 3(U M T S−T DD) = -20.9dBm

   (e) IIP 3(802.11) = -22.5dBm

  In conclusion, the IIP3 requirement for this platform is limited by the high-
  est, which is DCS1800 and it is : -18dBm.

4. Noise Figure

  The NF, noise figure, is a parameter used to measure how much the SNR

  is degraded as the received signal progress through the receiver [16]. It can
  also be defined as the available SNR as the ratio between the available SNR

  at the input and the output of a network. NF is the figure in dB of the

  noise factor, F. Using this definition the following equation calculates the

  noise factor for a single network:

                                            Sg N
                                    F =(       )( )                       (3.5)
                                            ktb S

                                       27
where Sg is the available signal power at the input, ktb is the available

noise power at the input, N is the available noise power at the output of
the network and S is the available signal power at the output of the network.
KTB is the thermal noise, at 290o K this is -174dBm/Hz. Hence including

the bandwidth of interest, the noise power at the receiver input in dBm is:


                N oiseF loor = [−174 + 10 log(BW )](dBm)                (3.6)


The noise figure NF for a single network is given below:


     N Fov (dB) = Pmin + 174dBm/Hz − SN Rreq − 10 log(BW )              (3.7)


The NF specifications for the covered standards are studied in order to
generate the NF requirements of the system:

(a) N F(DCS−1800) = 11.8dB

(b) N F(P CS−1900) = 9.8dB

 (c) N F(U M T S−F DD) = 9.6dB

(d) N F(U M T S−T DD) = 9.2dB

 (e) N F(802.11) = 11dB

The noise figure for the system is calculated using the Friis [17] method

given in equation (3.8). The input and output impedance of all networks

components in the system are assumed to be 50 Ω. In order to obtain the

NF for the different stage in the system the gain of each independent stage
can be used. The equation below gives the total NF for an m-stages system.

                                      m
                                            Fi − 1
                     Ftotal = F1 +         m−1                          (3.8)
                                     i=2   k=1 Gaink
                          N Ftotal (dB) = 10 log Ftotal                 (3.9)


where Fi and Gk are the noise factor for each stage and gain of each element

                                     28
     respectively. N Ftotal is referred to the total noise figure for the system.

     In order to calculate the NF of this platform the schematic of Figure 3.6 is
     used.



         BPF             LNA           DEMOD.            LPF            ADC
RS                                                                                 RL
        F1,G1           F2,G2            F3,G3           F4,G4          F5,G5


                Figure 3.6: Noise networks in the receiver.



                           N Fi
                 Fi = 10    10                                                  (3.10)
                           Gi
                 Gi = 10 10                                                     (3.11)
                                  F2 − 1 F3 − 1   F4 − 1     F5 − 1
                 Ftotal = F1 +          +       +         +            (3.12)
                                   G1     G1 G2   G1 G2 G3 G1 G2 G3 G4
                 N Ftotal (dB) = 10 log Ftotal                                  (3.13)


     A particular case in the calculation of the single NF in the m-stages system,
     showed in the previous figure, is the NF of the ADC. This is due to the
     high influence that the dynamic range of the ADC has over the noise factor
     of the device. The NF of the ADC is calculated as follows [18]. From
     the SNR given in the data sheet and the full scale voltage, V fs(RM S) , the

     effective input noise voltage is calculated, Vnoise(RM S) , using equations (3.14)

     and (3.15). The noise factor, F, is then given by the effective input noise

     divided by the thermal noise as shown in equation (3.17). Using this result
     the noise factor is then given by equation (3.18) and the NF is then F in




                                         29
     dB given in equation (3.20).

                                      V fs(RM S)
                  SN R = 20log                                              (3.14)
                                     Vnoise(RM S)
                                                    −SN R
                  Vnoise(RM S) = V fs(RM S) 10       20                     (3.15)
                                2
                           V   fs(RM S)
                  PF S =                                                    (3.16)
                                 R
                                 2
                               Vnoise(RM S)
                  FADC =                                                    (3.17)
                            KT RB
                                   1     −SN R 1
                  FADC   = PF S ×    × 10 10 ×                              (3.18)
                                  KT           B
                  N FADC (dB) = 10 × log Ftotal                             (3.19)
                                                                       fs
                  N FADC (dB) = PF SdBm + 174dBm − SN R − 10 log            (3.20)
                                                                       2

     PF SdBm is the full scale input power. This is the power of a sinewave
     which has an amplitude peak-to-peak that fills the ADC input range. In

     equation(3.20), fs is given in Hz and it is the sample frequency of the ADC.

     Consequently the N Ftotal is calculated to meet the required specifications
     of 11.8dB that arise from the DCS1800 standard.

Receiver specifications have been described in this section. Thus, the input signal
going to our SDR receiver is required to have: low power (down to -107dBm),
considerable high dynamic range, channel bandwidth up to 22MHz, and a center

frequency which is varying between 1.6GHz to 2.4GHz. In order to design the

requirements for the output signal from the SDR front-end, transmitter specifi-

cations are described in the next section.


Transmitter Specifications

The purpose of the transmitter is to modulate the desired signal, shift it to RF,

and amplify an RF carrier. The specification design for the transmitter is more

relax than for the receiver. This is because some of the parameters can be consid-
ered from the receiver for the design of the transmitter, such as the noise figure.

The most important design parameters to create the transmitter specifications


                                              30
are: phase noise, output power level, power control range and frequency of op-

eration. The frequency of operation for this SDR platform has been described
previously since the band of covered standards was given. The rest of design
parameter values are described as follows:

  1. Output Power Level
     This is the power level of the transmitted signal from the antenna. The

     maximum output power levels for the covered standards are described be-

     low:

      (a) P(DCS−1800) = 36dBm

      (b) P(P CS−1900) = 36dBm

      (c) P(U M T S−F DD) = 33dBm

      (d) P(U M T S−T DD) = 24dBm

      (e) P(802.11) = 11dBm

  2. Power Control

     This is the controlled variations in the output power level of the transmitted
     signal from the antenna. Thus the transmitter in this platform has output

     power control to comparative fine tolerances. The power control range is
     given by the DCS1800 specifications, 36dBm of power control range with

     steps of 2dB.

  3. Transmitter Phase Noise

     This noise is expressed in terms of single sideband phase noise (PN) mea-

     sured in a 1 Hz bandwidth at an offset from the carrier relative to the carrier
     amplitude. This phase noise in the transmitter is mainly caused by noise

     coming from the PLL on the up-conversion stage.

     The PN specifications for the covered standards are given below:

      (a) P N(DCS−1800) = -154dBc/Hz

      (b) P N(P CS−1900) = -154dBc/Hz

                                       31
        (c) P N(U M T S−F DD) = -148dBc/Hz

        (d) P N(U M T S−T DD) = -154dBc/Hz

        (e) P N(802.11) = ?

     The phase noise for the standard 802.11 is not specified since this depends

     on the used modulation scheme. However, the PN requirement in 802.11 is

     more relaxed than the other standards. Hence, the hardest PN constrain

     to meet is -154dBc/Hz which arises from the DCS1800 standard and forms
     the requirement for this platform.

From the specifications described above, the output signal from the transmitter

is required to have: differential mode (I and Q channels), output power up to

30Bm, center frequency between 1.6GHz and 2.4GHz, enough signal power to
ensure a high SNR, a controlled dynamic range to meet the requirements for the
ADCs. The requirements for the ADC are explained in the next section.


3.3.2     Analog-to-Digital Conversion Specifications

The baseband processing stage provides optimum digitization, fast sample rate
conversion and configuration control for the system. In addition, the baseband
block of this platform must meet the requirements for 2G/3G, 802.11 and 802.16

standards. Hence, the specifications of this block are directly derived from the

signal characteristics incoming and out going to and from the system. Spurious
emissions by the transmitter are controlled by careful selection of the DAC. In

order to specify the ADC the blocker characteristics of the receiver for the covered

standards need to be considered. These parameters decide the dynamic range of

the signal and, as a consequence, of the baseband block.


To achieve the signal to noise ratio in the covered standards a minimum ADC res-
olution is required. This resolution depends on the number of bits per symbol, the

blocking performance and the required receiver sensitivity. As the bits/symbol


                                        32
increases the SNR requirements of the receiver increase. This is reflected in the

number of bits in the ADC. Thus, a constellation such as Orthogonal Frequency-
Division Multiplexing, OFDM, will require more bits than simple Binary Phase
Shift Keying, BPSK. For this reason OFDM is used as the worst case example in

the simulations described here.



OFDM is a technique which combines digital modulation schemes with the prin-




                   Figure 3.7: Flow chart of BB simulation.


ciple of frequency division multiplexing, FDM. This technique is used to preserve
orthogonally in multi-path environments when large amounts of digital data are


                                       33
transmitted. In OFDM the frequency spectrum is divided into sub-channels, then

each sub-channel transmits a bit stream by modulating a sub-carrier. The sub-
channels are combined together using the inverse fast Fourier transform, IFFT,
thus the receiver separates the channels by using the fast Fourier transform, FFT.

In order to eliminate the cross talk between sub-channels the sub-carrier frequency
is chosen so that the modulated data sub-channels are orthogonal to each other.

For the sub-carrier modulation several modulation schemes were used such as :

M-QAM, QPSK and BPSK. In the simulations the parameters of the signal are

modified in order to represent different transmission scenarios. Table 3.4 lists the

signal parameters that were modified. Therefore, simulations are done for several


                       Table 3.4: Simulation Parameters.




modulation schemes, number of carriers, channel noise and number of bits. The

transmission channel is represented by the addition of White Gaussian noise into
the signal. In the receiver the cyclic prefix of the OFDM signal is removed before
reaching the uniform quantizer, which adds quantization noise to the signal. This

is possible due to the assumption of perfect synchronisation between the trans-
mitter and the receiver. The BER (bit error ratio) is calculated at the output

of the system. Since the OFDM signal introduced into the system is a random

process, the SNR calculation requires the variance of both information and noise

signals. In order to achieve the specified BER from the standards, the required
minimum number of bits in the ADC is sought. This process is shown in the

Figure 3.7.



                                        34
In the following equations the calculations of this process are presented. The

Matlab code used for the is included in appendix A. Equations (3.21) and (3.22)
give the expected value or mean (µ) of both noise and information signal, where
n is the system noise and ofdm is the information signal.

                              Plnoise
                                         ni
                      µn =      i=1
                                lnoise
                                                     lnoise : noise length      (3.21)
                              Plof dm
                                        of dmi
                   µof dm =     i=1
                                   lof dm
                                                        lof dm : ofdm length    (3.22)



                                         k
                              λ2
                               n   =          (ni − µn )2                       (3.23)
                                       i=1
                                               k
                              λ2 dm
                               of        =          (of dmi − µof dm )2         (3.24)
                                              i=1

                               2      λ2
                                       n
                              ξn =                                              (3.25)
                                    k−1
                               2
                                       λ2 dm
                                         of
                              ξof dm =                                          (3.26)
                                        k−1
                                                           k
                               2        1                        2
                              σn   =           ·                ξni             (3.27)
                                     samples 2            i=1
                                                                k
                               2                 1                     2
                              σof dm =                  ·             ξof dmi   (3.28)
                                              samples 2         i=1




In the above equations k is a variable which counts from 2 up to the number of
samples used for the simulation, λ2 is the temporary variance of both signals, ξ 2

is the sample variance, which is an estimated variance and is based on a finite
sample, and σ 2 is the total variance for both signals. The variance of both noise

and information signals converge as shown in Figure 3.8. These are simulated

using equations (3.23) to (3.27). It can be seen in Figure 3.8 that a significant
number of samples are required in order to accurately represent the variance of

the OFDM signal. The number of points in the OFDM signal constellation is ef-

fectively the number of points in the underlying sub-channel modulation scheme

times the number of sub-channels. This gives a large peak to average ratio re-


                                                   35
sulting in the requirement for a large number of samples in the simulation.


Equation (3.31) is used to calculate the signal to noise ratio of the system which
is modelled with Matlab.


                                                 2
                                           Sσ = σof dm                                 (3.29)
                                                 2
                                           Nσ = σn                                     (3.30)
                                                                    Sσ
                                           SN R = 10 · log10 (         )               (3.31)
                                                                    Nσ



                         11                    Converging Variance ofdm
                     x 10
                3

               2.5
Variance(V2)




                2

               1.5

                1

               0.5
                     0        200        400            600               800   1000    1200
                                                      sample
                         8
                     x 10                  Converging Variance noise
               3.5

                3

               2.5
Variance(V2)




                2

               1.5

                1

               0.5
                     0        200        400             600              800   1000    1200
                                                       samples


                                    Figure 3.8: Converging Variance.


In order to calculate the BER with the obtained SNR previously, different for-

mulae must be used for each sub-channel constellation.




                                                      36
                                                                           √
                                                         P e = 0.5 · erf c( SN R)                                                     (3.32)

                                             P e = 2 · (1 −      √1 )         · erf c                3
                                                                                                            · SN R                    (3.33)
                                                                  M                              2·(M −1)

                                             P e = 2 · (1 −      √1 )         · erf c                3
                                                                                                            · SN R                    (3.34)
                                                                  2·M                            2·(M −1)

                                                                               2      ∞ −u2
                                                         erf c(x) =           √
                                                                                π     x
                                                                                        e du                                          (3.35)




                    Equation (3.33) calculates the probability of error for BPSK, equation (3.34) cal-

                    culates the probability of error for QAM(16,64,256) and equation (3.35) calculates
                    the probability of error for QAM (8,32). Equation (3.35) is the complementary
                    error function. Figures 3.9(a) and 3.9(b) show the BER versus SNR for two dif-

                    ferent types of modulation scheme: 256 QAM, 32 QAM. These results are given

                    as a function of the number of quantization bits.



                                    32 QAM                       resolution            1
                                                                                                                       256 QAM                        resolution
       5
      10                                                                              10
                                                                    4                                                                                     4
                                                                    5                                                                                     5
                                                                    6                                                                                     6
       0                                                            7                                                                    4bits            7
      10                                                                               0                                                                  8
                                                                    8                 10

       −5
      10
                                                                                       −1
                                                                                      10
       −10
      10
                                                                                BER




                                                                                       −2
BER




       −15
      10                                                                              10


       −20
      10
                                                                                       −3
                                                                                      10

       −25
      10

                                                                                       −4
                                                                                      10
       −30
      10


       −35                                                                             −5
      10                                                                              10
            20       30   40   50     60       70   80      90          100                20       30       40   50     60      70     80       90           100
                                     SNR                                                                                SNR


                 (a) BER vs SNR with 32QAM modulation.                                          (b) BER vs SNR with 256QAM modulation.

                                                            Figure 3.9: BER


                    It can be seen from this that at least 8 bits are required to achieve the necessary

                    BER. Additional bits are added to allow for signal amplitude variation at the
                    input of the ADC. Thus, 16-bit ADCs can be used which gives 8 bits of dynamic

                                                                              37
range to allow for amplitude variation in the incoming signal. This corresponds

to 48dB of dynamic range available at the input to the ADC. This allows the
relaxation of the requirements for the automatic gain control in the receiver. The
previous plots have been created with the code in appendix A.



3.4     Implemented Architecture

The obtained specifications require a platform to transmit and receive across

the band from 1.5GHz to 2.5GHz with a receiver sensitivity of -117dBm. This

requires a NF of 9dBm and the phase noise of -154dBc/Hz. To achieve the specifi-

cations an architecture that can tune across this band and meet the tight receiver
specifications is required. In reference with the architecture described in chapter
2 a suitable architecture is now selected. The superheterodyne model is the most

common architecture for wireless communication. However requirement for an
intermediate frequency, and the associated filters, make this architecture difficult
to tune across a wide frequency band and thus unsuitable for SDR purposes [14].



Low-IF architecture is a possible solution for SDR, however the necessity of an
accurate image rejection filter renders this a difficult architecture to implement.


The remaining option is the direct conversion architecture. This technique trans-

forms the RF signal to zero frequencies at down-conversion and from zero frequen-

cies to RF at up-conversion using just one conversion stage. On the transmitter

side this architecture has the disadvantage of injection pulling. This issue is due

to leakage from the local oscillator to the PA. This arises as the signal at the

output of the power amplifier is a modulated high power signal with spectrum
centred around the LO frequencies. Without careful design some of the output

power may leak into the LO affecting the performance of the system. To solve

this problem the mixer in the modulator must be highly isolated. Similarly the
receiver may experience DC offset problems associated with the LO leakage and

                                        38
power coupling to the input of the LNA. This is illustrated in Figure 3.10 as

an example of some of the drawbacks and requirements of the direct converter
receiver. Although it has the disadvantage of DC offset, a complex image re-




              Figure 3.10: Direct converter receiver requirements.


jection filter is not needed in the direct conversion architecture. In addition the
problems caused by the DC offset are easier to solve. Double balanced mixers
and accuracy in phase quadrature and amplitude balanced in the LO with good

isolation between the LNA and the LO, are reliable solutions in the direct con-
version architecture.



Direct conversion is power efficient, has easy tuning across large frequency bands,
and low cost because of a reduced number of components. This guarantees a

higher level of integration than with other architectures [14]. Good image sup-

pression properties result from this approach. This SDR system must support
non-linear modulation schemes such as GMSK, linear modulation schemes such as

QPSK and quadrature modulation schemes such as QAM. In order to avoid signal
distortion due to saturation in the low noise amplifier (LNA) and power amplifier

(PA), there is a requirement for variable gain in the system [19]. Consequently

                                       39
the PA is preceded by a variable gain amplifier which avoids the saturation of the

PA. Considering the receiver, the signal gain is controlled by an automatic gain
control, AGC, in the demodulator.


3.4.1    SDR Specifications and Block Diagram

The baseband and RF specifications have been created from the requirements

explained in this chapter. Table 7.2 is presenting the resulted specifications for
the design of this system.


                             Table 3.5: Specifications
    Receiver                 Transmitter        Baseband
    IIP3: -0.87dBm           Pout : 30dBm       ADC/DAC resolution: 16bits
    Sensitivity: -107dBm     PN: -152dBc/Hz     Sample rate up to 100Msps
    BW: 22MHz                BW: 22MHz          480Msps USB link
    Frequency range : 1.6GHz to 2.5GHz
    Standards: DCS1800, PCS1900, UMTS-FDD, UMTS-TDD and 802.11b




Given these requirements, a suitable platform in the direct conversion archi-
tecture has been selected. The proposed block diagram for the design of this

platform is illustrated in Figure 3.11. The system is separated into three blocks
according to their frequency characteristics.



3.5     Conclusion

Some limitations and requirements have been presented in this chapter. The cho-

sen architecture has also been presented in this chapter. The proposed platform
is only able to meet some of the wireless telecommunications standards due to the

difficulty in creating a pure SDR system capable of adapting to any environment.

A family of standards with similar characteristics has been selected compatible
with SDR implementation to be covered by this model. In the following chapter,


                                        40
  RX

                                                                ADC
                                                                             BB
                    LNA
                                  o
                                90
                                             LPF



                                                                ADC



                                                                      USB    To
                                                                            Computer

  TX
                                                                DAC

               PA    VGA               o
                                      90
                                                      LPF


                                                                DAC




                    Figure 3.11: Block diagram of the system.


the designed SDR testbed is presented taking in consideration all the studied
requirements given in this chapter.




                                       41
Chapter 4

PLATFORM DESIGN


4.1     Introduction

In this chapter the design of the implemented platform is presented. Character-
istics for the different stages of the platform are given. Analog-to-digital conver-

sion, modulation and demodulation, and baseband signal processing stages are
described, and manufactures part numbers are detailed. RF amplification and
filtering stages are explained in detail in the following chapters.



At the receiver front-end, the antenna collects the signal. This is then filtered
and demodulated to baseband frequencies. The fact that most of the components
at the receiver are broadband devices enables the sweep of frequencies over a very

wide range. The signal characteristics are analyzed using digital signal processing

on the PC.



In the same way as the receiver, the transmitter performs the up conversion. The
RF synthesizer outputs a signal with the desired centre frequency to the mixer

which up converts the modulating signal to the desired transmit frequency. This

is then further amplified and filtered before reaching the antenna. During this

process of transmitting and receiving the signal, the hardware may be adapted
under software control to match the specifications of the particular standard.

                                        42
4.2      Platform Overview

Following the block diagram of Figure 3.11 given in the previous chapter, the

platform with the corresponding device part numbers is illustrated in Figure 4.1.
This design is divided into three functional blocks: radio frequency receiver, radio
frequency transmitter and base band interface [20]. The implementation reflexes

this layout. Since one of the most difficult challenges to satisfy in reconfigurability
is the analog-to-digital conversion and digital-to-analog conversion stage, it was

the starting point. The results of the simulation for the ADC requirements were
presented in the previous chapter. These simulations were carried out to with

the target of finding the minimum resolution needed to fit the SNR limitations

for the worst case standard to be implemented here. The platform consists of a
USB interface to a standard PC, an ADC and a DAC and a direct conversion

architecture for transmitter and receiver.

    RX                                                              BB
                                  AD8347                  LNA

                                                                     ADC

               LNA                    o                   AD8132
                                     90




                      MBC13720                                       ADC

                                                          AD8132
                                                                   LTC2205
                                                ADF4360                              To
                                                                               USB
                                                                   CY7C68013         Computer
    TX
                                 AD8349                              DAC

                 PA      VGA                     o   AD8132
                                                90


                      ADL5330                        AD8132
               MGA83563                                              DAC

                                                                   MAX5875
                                                      ADF4360




                      Figure 4.1: Block diagram of the system.




                                           43
4.3     USB Interface and Digital Control Plane

In order to exchange data and information between the PC and the hardware plat-

form the USB2.0 standard is used. The interface between the USB host and the
platform is implemented by a high speed peripheral controller from Cypress Semi-
conductor. This chip contains both an 8051 microcontroller and a programmable

peripheral interface. The microcontroller is programmed using the C language.
Interrupts are used to control the exchange of data between the platform and the

PC. The code used to control the system is given in appendix B. Parameters such
as clock frequency in the 8051, center frequency of the transmitter and receiver

front-ends and output power are programmed in the PC and downloaded to the

microcontroller which controls the rest of the platform. In this way the platform
may be reconfigured.


4.3.1    Synchronization and Control

The clock waveforms required for the ADC and DAC are generated here. All

the control signals are processed by the baseband board. Timing functions are
implemented from this part by digital signal processing. The ADC has a parallel

pipeline architecture with a latency of seven clock cycles. The DAC has a switched
current architecture with a propagation delay of 1.5ns and a latency is 5.5 clock

cycles. The data is data is latched into and out of the USB chip. From this

information the required time diagram is shown in Figure 4.2.



4.4     Analog to Digital and Digital to Analog

        Conversion Stages

Analog to digital conversion, ADC, is critical for the operation of the system.

This is one of the most important steps in a communications system since the
signal can be distorted due to non linear affects and information can be lost due


                                       44
 >6.25ns   >6.25ns

                                                                  Master clk



                                                                 Inverted Master clk




                                                                   I convert clk



1111111111111111 11111111111111
0000000000000000 00000000000000
< 5ns

  00000000000000 00000000000000
  11111111111111 11111111111111
                                                                   Valid I ADC data



111111111111111111111111111111
000000000000000000000000000000
        11111111
        00000000
000000000000000000000000000000
111111111111111111111111111111
                        111111
                        000000
                     < 5ns
000000000000000000000000000000
111111111111111111111111111111
                                                                   Valid I Latch output
                                                                   L and OE driven from
                                                                   I convert clk


                                                                  Q convert clk



        11
        00
00000000 00000000000000 000000
11111111 11111111111111 111111
                     < 5ns
11111111 11111111111111 111111
00000000 00000000000000 000000
                                                                   Valid Q ADC data


111111111111111111111111111111
000000000000000000000000000000
11111111
00000000
000000000000000000000000000000
111111111111111111111111111111
< 5ns
                 111111
                 000000
                                                                   Valid Q Latch output

111111111111111111111111111111
000000000000000000000000000000                                     L and OE driven from
                                                                   Q convert clk


                             Figure 4.2: Time Diagram.


to lack of resolution in the conversion process. With the advents of more com-

plex constellations such as OFDM the demand for higher resolution has increased
in the last few years. Consequently 16 bits ADCs with the required bandwidth
are becoming available in the market. These are replacing the previous available
state-of-the-art ADCs for wireless applications which were 14 bit resolution de-

vices operating with 100MHz sample rate. Converters with 16 bit resolution can
process higher dynamic ranges and achieve the requirements for most of the stan-
dards needed here. In a wide band system SFDR (Spurious Free Dynamic Range)

is the most important limitation for the choice of a particular ADC [21]. This is

because aliased spurious tones on the carrier can fold back on the carrier causing
distortion. This affect is further exasperated in multicarrier systems. From this

point of view Matlab simulations were carried out to calculate the minimum res-

olution required for the converter. This is documented in chapter 3.


For the digital to analog conversion (DAC) stage high performance DACs are

used in the transmitter. Thus the complete signal is reconstructed from the
digital data. The DAC performance is very important since the SDR platform

                                        45
performs most of the signal processing digitally. Working in the digital domain

results in improved reconfigurability and programmability which is the purpose
of implementing SDR systems.


4.4.1     Implementation

ADCs

The choice of the ADC architecture depends on what kind of capability is im-

portant for this platform. Jitter in the ADC stage degradates the SNR in the
system. For this reason an ultra low jitter ADC is chosen. The SNR degradation

due to the jitter is given by the following equation [21]:


                        SN R = −20 log10 (2πfin × tjitter )                   (4.1)

In addition, conversion speed is another requirement for SDR. Different ADC
architecture required different numbers of clock cycles per sample. Figure 4.3

shows a qualitative comparison of ADC techniques relating the resolution and
number of clock cycles used per sample. From this figure the fastest architec-
ture is flash or pipeline. Hence a 16 bit ADC which uses the pipelined multistep
technique is used. The devices chosen are the LTC2202/LTC2205/LTC2207 fam-

ily from Linear Technologies. This family are pin compatible with each other.

Currently the sample rate needed is not greater than 80Msps, consequently in
order to avoid excessive power consumption the LTC2205 is used. Nevertheless

the target is to achieve the maximum sample rate possible, thus the LTC2207

capable of sampling at 130MSps may also be used in this platform. This ADC
(LTC2205) is composed of five pipelined ADC stages with a differential analog

input to reduce even harmonics, increase the input range and improve common

mode noise immunity [22]. Some of the advantages of the pipeline architecture
are: digital correction with no increase in hardware size. However it requires

fast interstate processing since the architecture is implemented in several stages.



                                        46
               Figure 4.3: Comparation of ADC techniques [21].

Figure 4.4 illustrates the block diagram of the chosen ADC.




               Figure 4.4: ADC Functional Block Diagram [22].


The timing jitter on the conversion for this ADC is 90fs, which does not con-
tribute to a significant degradation in the SNR. The noise figure, NF, for the

ADCs is calculated using equations (3.16) to (3.20) and it is 10.2dB. As shown

                                      47
in Figure 4.1, two ADC devices are used, one for the in-phase and one for the

quadrature channel. They are situated just after the baseband filter and amplifier
which scale the signal to a suitable level for analog to digital conversion.


DACs

The reconstructed analog signal from the DAC must represent the digital signal
accurately. The major source of errors in the DAC is due to static nonlinearity.

These occur when the level spacing in the DAC is non-uniform. These errors
result in distortion which may cause spurious tones and degradation in SNR.

SFDR gives a measure of this effect. As for the ADCs, SNR, SFDR and sample

rate are the most significant parameters.

The maximum SNR is derived from the resolution of the DAC and is described
as following:

                          SN R = 6.02dB × N + 1.76dB                           (4.2)

However, as in the ADC, jitter and thermal noise affect this ideal SNR. The
chosen DAC device is the MAX5875 from MAXIM [23]. The device features a
SFDR of approximately 80dBc, a sample rate up to 200Msps and a noise density

of -162dBFS/Hz which meets the required specifications for the transmitter. The
device is dual channel with 16 bit resolution implemented using a current steering

architecture as illustrated in Figure 4.5. As shown in Figure 4.1 one DAC is used
for the I channel and one DAC is used for the Q channel.



4.5      Baseband Signal Processing

This section describes the two stages of baseband processing: filtering and am-

plification. The receiver gain is the sum of the LNA, mixer and baseband am-
plification stage gains. The mixer gain control is used to provide variable gain

in the receiver. Therefore the gain of the baseband stage can be controlled. A

low pass antialiasing filter is included between the demodulator and the ADC to


                                        48
                  Figure 4.5: DAC Functional Block Diagram [23].


prevent spurious high frequency signals from corrupting the wanted signal. The
amplification and filtering at the receiver are implemented using multiple feed-

back architecture. Similarly in the transmitter a baseband gain stage is used to
fit the output of the DAC to the input of the modulator. In the transmitter a low

pass reconstruction filter follows the DAC. Again the amplification and filtering
stages are implemented using multiple feedback architecture. This filter must
have a cut-off frequency similar to the bandwidth of the signal that is going to

be transmitted.


4.5.1    Filtering

The baseband filtering is composed of two low pass channel selection filters. They

are situated close to the DAC in the transmitter side, and to the ADC in the re-
ceiver side. The filters are acting as antialiasing filters and are implemented for

this platform to ensure suppression of out of channel interference. The receive

filter eliminates interfering signals that may be within the bandwidth of the de-
modulator but outside the bandwidth of the ADC. This filter in effect acts as the


                                       49
channel selection filter. The main requirements of the channel selection filters

are: high selectivity, low power dissipation and high dynamic range. Therefore,
analog filters instead of digital filters are implemented because of their lower
power consumption and higher dynamic range. A Multiple-Feedback architec-

ture is implemented (Figure 4.7). Capacitors C1, C2, C3 and C4 add two poles
to the transfer function giving a roll-off of 40dB per decade. C5 and C6 add an

additional pole at the output. The filter is designed to have 5 MHz bandwidth at

3dB gain reduction. The same filter is used on the transmitter and the receiver.

Figure 4.6 shows the filter phase and magnitude response.




                Figure 4.6: Low Pass Filter Frequency Response.




4.5.2    Amplification

The receiver amplifiers are implemented using the analog devices AD8132 opera-

tional amplifier. These are differential (input and output) operational amplifiers

with a maximum gain of 20dB [24]. The amplifier and filter are implemented in
the same circuit using multiple feedback architecture. This circuit is shown in

Figure 4.7. The feedback networks are comprised of two equal value feedback re-
sistors, and two equal value gain resistors. R3 , R5 , R4 and R6 determine the gain

of the Multiple Feedback model as is presented on the following equations [24].

                                                     R3
                                Gain1 = 20 · log10                            (4.3)
                                                     R5
                                                     R4
                                Gain2 = 20 · log10                            (4.4)
                                                     R6



                                        50
For the calculation of the correct gain for the operational amplifier the input char-

acteristics of the ADC device are taken into consideration so as to get the best
noise performance. The gain control of the down-converter is used to provide a
fixed amplitude of 500 mVp-p at the output of the demodulator. This allows the

largest region of linearity at the demodulator output for any given input. There-
fore the amplifier is able to work in the linear region for the selected frequency

range. Considering the output amplitude of 500 mVp-p, 250 mVp or 23dBm, the

basband amplifier requires a gain of approximately 13.1 dB to provide a full scale

input to the ADC. The AGC (Automatic Gain Control) on the demodulator has

a steady-state voltage of 1V with an expected input of 24 mVp-p. Resistors are
used as a voltage divider to provide the 24 mVp-p from the 500mVp-p signal.

With these values it is possible to calculate the control resistors for the AGC.
Thus, the obtained resistors values are 20kΩ and 1kΩ.




             Figure 4.7: Base Band Amplifier and Low Pass Filter.




4.6      Down-Conversion and Up-Conversion Stage

Both down-conversion and up-conversion stages are implemented as direct con-

version architectures. A synthesizer consisting of voltage controlled oscillator,

PLL and reference signal is used to provide the center



                                        51
4.6.1     Specifications

The mixer in the modulator and demodulator used in the transmitter and receiver

is required to meet certain specifications such as noise, linearity and isolation. The
noise generated by the mixer, which is represented by its noise figure, directly
contributes to the SNR of the received signal. High linearity, measured by the IP3,

is required to avoid intermodulation products [25]. Finally good isolation between

the ports of a mixer is required to avoid signal leakage. Signal leakages may occur

between the LO and RF inputs. Therefore in the receiver an LO to RF feeding-

through may produce a leakage to the LNA and hence the antenna. Feeding-
through from the RF port to the LO port in the transmitter may also result
in injection pulling in the LO. Also LO/baseband feed through is particularly

important. If large LO signals appear at the baseband output the following stage
may be desensitized. A further figure of merit for the mixer is the conversion
loss. This is the ratio between the RF input power and baseband output power
and is described as follows [26]:

                                     RF input power
                    Lc = 10 log                         dB                      (4.5)
                                  Baseband output power



Thus the mixer is specified by isolation, conversion loss, 3rd order intermodu-

lation product and the standing wave ratio (SWR). Table 4.6.1 presents these
performance parameters for different mixer architectures.

                  Table 4.1: Mixers Characteristics [26]
    Mixer Type      RF SWR       RF/LO Isolation          Lc                3o Order IP
   Single ended        Poor            Fair              Good                 13 dBm
   Balanced(90o )     Good             Poor              Good                 13 dBm
               o       Fair          Excellent           Good                 13 dBm
  Balanced(180 )
 Doubled Balanced      Poor          Excellent         Excellent              18 dBm
  Image rejection     Good            Good               Good                 15 dBm


The architecture is considered single-ended, balanced (90o ), balanced (180o ),

double-balanced and image rejection. Depending on which configuration is used,

                                         52
single or double, the behaviour in the presence of noise varies. The single balanced

configuration (single RF and differential LO) has less input noise but the double
balanced configuration generates less even-mode distortion. In addition, a differ-
ential RF output provides more immunity to feed through of the RF signal to

the baseband IF [25]. A balanced mixer usually produces an optimum RF SWR
(Standing Wave Ratio). This a measure of signal mismatch with a value of 1 in-

dicating a perfect match. Finally the mixer output may contain spurious signals

due to the non linearity of the mixer. These are generated by intermodulation

and cross products of the RF and IF signals and the corresponding harmonics.

It is necessary that these components do not fall within the signal band of interest.


Since the architecture used in this SDR platform is the direct conversion architec-
ture, the signal is down-converted to zero frequencies and not to IF frequencies.
A balanced mixer is used, which avoids the requirement for an image rejection

filter. However to reduce leakage from the LO in the synthesizer to RF and base-
band an accurate frequency synthesizer with amplitude balanced in phase and
amplitude outputs is required.


4.6.2     Frequency Synthesizer

The synthesizer utilized is the Analog Devices ADF4360 [27]. This device is

composed of a divided by N-PLL and a VCO integrated in the same chip. The

device is has a 3-wire serial interface for control. Signals can be sent through

this interface to control the frequency sweep and the RF power output of the

chip. The desired frequency is programmed through software in the C language
over the serial interface. The flow chart from Figure 4.9 describes the sequence

followed to configure each register in the PLL. In this flow chart the programming
from power-up for the ADF4360 starts with the R counter latch, followed by the

control latch, finishing with the N counter latch. The device includes a 24 bit

input shift register, a 14 bit R counter and an 18 bit N counters. The data is


                                         53
                    Figure 4.8: ADF4360 Block Diagram [27].


clocked into the 24 bit register on each rising edge of the CLK signal [27], and it
is transferred from this register to one of the latches on the rising edge of the LE
signal. The parameters of the synthesizer are calculated as follows [27].


                         fV CO = [(P × B) + A] × fref /R                       (4.6)


Where fV CO is the desired centre frequency at the output(2.08 GHz or 2.35 GHz),
P is the prescaler value, A and B are the counter values, fref is the reference

frequency and R is the R counter value. The two phase frequency detector inputs

are: P DF1 and P DF2 given as follows:

                                             1
                               P F D1 =                                        (4.7)
                                          N × fV CO

                                               fref
                                  P F D2 =                                     (4.8)
                                                R



                                          54
                  Figure 4.9: PLL Configuration: Flow Chart


N is expressed as follows:
                              N = (P × B) + A                            (4.9)

The minimum N possible is:


                               Nmin = P 2 − P                           (4.10)


The counters only work if the prescaler output is less than 300 MHz. Thus:

                              fV CO
                                     ≤ 300M Hz                          (4.11)
                             P/P + 1




                                      55
The loop filter bandwidth is selected as 25 KHz; this is a trade-off between settling

time and phase noise in the VCO output. The PFD comparison frequency is
selected as 10 times the loop filter bandwidth at 250 KHz. This means that the
loop filter output is the average of the PFD output. Using a XTAL reference of

20MHz R is then given as follows:

                                 fref IN     20 × 106
                           R=             =                                 (4.12)
                                250 × 103   250 × 103

For a VCO output frequency of 2.35GHz applying the previous equations, the

values below were obtained: P=16, B=587, A=8, R=80, N=9400.


Modulator and Demodulator

The demodulator implemented is a direct conversion device with in-phase and

quadrature outputs. The device used in the implementation is the Analog De-

vices AD8347 [28]. Figure 4.10 gives the block diagram of this demodulator.
The device features two doubled balanced Gilbert Cell mixers for in-phase and




                 Figure 4.10: Demodulator: Block Diagram [28]


quadrature demodulation, improving the isolation between LO and with -60 dBm


                                        56
leakage into the RF path for and LO input of -8 dBm. The mixers are driven by

a pair of LO signals with 90 degrees in phase difference. This devices operates
across a frequency band from 800 to 2700 MHz. The device has a high third order
intercept point at 11.5 dBm. This also has two baseband amplifiers which may

be used to amplify the signal after filtering. However, in this case, in order to
reduce noise and the baseband output offset voltage the signal is amplified using

differential amplifiers off-chip. The off-chip amplifiers are implemented as active

filters with gain as detail in previously in section 4.5.



A high quality quadrature modulator is used, the Analog Device AD8349. It
generates an output frequency range from 700MHz to 2700 MHz. The device

is composed of: a LO interface, a baseband voltage-current converter, two mix-
ers, differential to single ended amplifiers and bias circuit. The device uses two
Gilbert cells as up-converted. It has an IQ amplitude balance of 0.1 dB and a

quadrature error of 1.9o . The block diagram of the chip is presented in Figure
4.11.




                  Figure 4.11: Modulator: Block Diagram [29]




4.7      Conclusions

This chapter has documented the ADC, DAC, modulation and demodulation and
baseband filtering and amplification sections of the platform design. Commercial

                                         57
off-the-shelf components have been used to implement this section of the platform.

Most of the specifications are met with these devices, however the reconfigura-
bility of the system needs to be improved. For example while the demodulator
and modulator can operate across a frequency range from 800 MHz to 2.5 GHz,

the synthesizer can only operate across a range from 2.05 GHz to 2.45 GHz.
Currently no commercial part is available to operate across the full band. The

design presented in this chapter is an implementation of an SDR system which

meets the required specifications within the limitations of commercially available

components.




                                       58
Chapter 5

RF FILTERING


5.1      Introduction

This chapter describes design and implementation for the filters needed in the
front-end of the platform. An RF filter is required at both the input to the

receiver and at the output from the transmitter. These act as band select filters.
The filter at the reciver input is responsible for attenuating unwanted out of band
signals. The filter at the output from the transmitter is responsible for suppressing

spurious transmissions. Ideally these filters would be reconfigurable in both center

frequency and bandwidth. However no such filters exist commercially, thus for
this platform a compromise has been reached. As reconfigurable RF filters are
not possible with current technologies the filter implemented here is a broad band

static filter. This places extra filtering requirements on the baseband section,

limits the blocker performance of the receiver, and requires high linearity from

the transmitter power amplifier. In both cases the filter is implemented using

microstrip coupled lines. The design steps and implementation for these filters
are presented in this chapter.




                                        59
5.2     Overview of Filter Design

The filter design is carried out as follows. Firstly a specification for the required

filter is developed. Once this is known a suitable low pass filter prototype is
selected such as Chebyshev, Butterworth or Bessel for example. Once the proto-
type filter is selected the filter order required is determinate. The prototype filter

transfer function coefficients are then calculated. Finally these are transformed
to the equivalent band pass filter and suitably impedance scaled. Once the the-

oretical filter is designed a suitable implementation is chosen. In order to meet
the implementation requirements of this platform these filters must be small in

size and low cost.



5.3     Specifications

The specifications for this filter are driven by the blocker specifications of the re-
ceiver. This project has available two frequency bands licensed for test purposes.

It is for this reason that the filters have been centered in these bands rather
than more typical commercial communication bands. However they have been
designed to meet the blocker specifications of the standards previously mentioned
in chapter 3. The two test frequencies are: 2.08GHz and 2.35GHz with 25MHz

of bandwidth each. The filter specifications are described as follows:

  1. Lower cutoff frequency: fL−3dB = 2.008GHz

  2. Upper cutoff frequency: fU −3dB = 2.422GHz

  3. Center frequency: f0 = 2.105GHz

  4. fL−20dB = 1.95GHz

  5. fU −20dB = 2.48GHz




                                        60
          0dB
          −3dB




          Gain
        −20dB

        −40dB
                      f L−20dB    f L−3dB       fo   f U−3dB   f U−20dB   frequency

                                 Figure 5.1: Filter Mask.


5.4      Filter Prototype

There are several possible filter prototypes are: Chebyshev, Butterworth, Bessel
and Gaussian filters. The Chebyshev filter has very good stop band attenuation

however it has ripple in the pass band. The Butterworth filter is maximally flat
in the pass band but it does not have as good stop band attenuation as the
Chebyshev filter. However both of these filters do not have flat group delay. The
Gaussian filter has flat group delay but at the expense of poor stop band attenua-

tion. The Bessel filter aims to improve on this by allowing some group delay ripple

resulting in improved stop band attenuation. The important parameters for the
filter for our application are gain flatness in the pass band and a good group
delay characteristic. The Butterworth filter offers the best compromise, and was

chosen to be implemented here. The Butterworth characteristic function is given

as follows [30]:
                                                    1
                                  A(w)2 =                                             (5.1)
                                                1 + K(w)2

The approximation for the characteristic function can be defined as :


                                            K(w) = wn                                 (5.2)




                                               61
The magnitude of the transfer function is given as:

                                                 G2
                             | H(jw) |2 =           0
                                                    ω                         (5.3)
                                              1 + ( ωc )2n

where n is the order of the filter, wc is the cutoff frequency or -3dB frequency for

the low pass prototype and G0 is the DC gain of the filter. The required order of
the filter is determined from the equation:

                                             1
                                 As ≥                                         (5.4)
                                                2n
                                           1 + ws

In doing so the following assumptions for the Butterworth filter are made: the

pass band edge is mapped to ωc = 1. The remaining parameter to be calculated
is the low pass equivalent stop band edge frequency. This is given as follows:

                                        2          2
                                       ωU −20dB − ω0
                                ωs =                                          (5.5)
                                       B × ωU −20dB

where ωs is the frequency for which the stop band attenuation is given, ω0 is the
                               √
center frequency given by ω0 = ωL × ωU , B is the band pass bandwidth. Thus

this results in 20dB attenuation at ωs = 5.9903rad/s. With this value the order

of the filter, n, is calculated using the following equations:

                                  log[1/(A2 )] − 1
                                          s
                               n≥                                             (5.6)
                                     2log(ws )

Using the last equation and specifications for the filter the obtained value for n

is 6. In order to calculate the transfer function H(s) the previous expression can
be transformed as:
                                                  G20
                            H(s)H(−s) =            −s2 n
                                                                              (5.7)
                                              1 + ( ω2 )
                                                      c


The resulting filter must be unconditionally stable, to achieve the filter polynomial

must be Horwitz. This equates to all the poles of the transfer function being in




                                         62
the left half ’s’ plane. The kth pole is given by:

                                                        j(2k+n−1)π)
                                            sk = ωc e        2n                         (5.8)


Thus with the previous equation the Butterworth polynomials can be obtained as
the denominator of the following transfer function written in terms of its poles:

                                                           G0
                                        H(s) =           n  (s−sk )
                                                                                        (5.9)
                                                         k=1 ωc


Assuming that wc = 1 it is possible to calculate the poles of the analog Butter-

worth filter prototype, these are given below:




                                        s1 = −0.2588 + j0.9659                         (5.10)

                                        s2 = −0.7071 + j0.7071                         (5.11)

                                        s3 = −0.9659 + j0.2588                         (5.12)

                                        s4 = 0.9659 − j0.2588                          (5.13)

                                        s5 = −0.7071 − j0.7071                         (5.14)

                                        s6 = −0.2588 − j0.9659                         (5.15)


Multiplying these poles together the transfer function can be written as [30]:

                                                       1
    Hs =                                                                               (5.16)
           s6   +   3.8637s5   +   s4   +   7.4641s3   + 9.1416s2 + 7.4641s + 3.8637

This is the transfer function of the low pass filter prototype. Regardless of how

the filter is to be finally implemented in hardware we require a prototype filter
implementation at this stage. The next step in this process is to synthesize a

circuit that implements this transfer function. A suitable filter topology is a

resistively terminated LC ladder structure. Component values for this may be

generated by continued fraction expansion of the driving impedance. This is de-


                                                    63
fined as the impedance looking into the input terminal when the output terminal

is terminated with a load resistor. For given filter orders there exist published
tables listing the element values [30] for normalized low pass filters. Figure 5.2
illustrates the general Π ladder network of a low pass filter prototype with the

following parameters: g0 , g1 , g2 ...gn+1 .




                          Figure 5.2: Π Network Prototype.


Figure 5.3 gives the equivalent T filter implementation, where g0 to gn+1 are the

corresponding inductor and capacitor admittances in the low pass filter model.
Using published tables [30] the following 6th order filter element values are ob-

tained [26]: g1 = 0.52; g2 = 1.42; g3 = 1.93; g4 = 1.93; g5 = 1.42 and g6 = 0.52.
These coefficients are scaled to the desired center frequency and transformed to
a bandpass transfer function.




                           Figure 5.3: T Network Prototype


To transform from low pass configuration to bandpass, the equations below are
used:


                                    ω2 − ω1                √
                             ∆=             ;       ω0 =       ω1 ω2       (5.17)
                                       ω0

For parallel elements:

                                      Cn                    Z0 ∆
                             Cp =          ;         Lp =                  (5.18)
                                    ω0 ∆Z0                  ω0 Cn

For series elements:
                                       ∆                       Z0 Ln
                            Cs =             ;       Ls =                  (5.19)
                                    ω0 Ln Z0                   ω0 ∆

                                               64
The resulting values are: C1=3.97pF, L1=1.30nH, C2=0.19pF, L2=27.18nH,

C3=14.87pF, L3=0.35nH, C4=0.14pF, L4=37.18nH, C5=10.87pF, L5=0.48nH,
C6=0.52pF, L6=9.94nH




                      Figure 5.4: Bandpass Filter Prototype.




5.5      Filter Implementation

The filter may be implemented in several possible technologies. Among these

are lumped components implementation, microstrip coupled line implementa-
tion, strip line filters, SAW filters, metallic and dielectric cavities and distributed
resonator structure sections. The implementation of RF filters using lumped

component LC structures is difficult in this frequency range as the component
values are at the bottom end of the range of the available values and the wave

lengths involved are comparable to the dimensions of the required circuits. This
means that a distributed circuit treatment is required.


5.5.1     Overview to Microstrip Filters

Microstrip is a planar transmission line technology. It is the most popular ap-

proach for the realization of circuits in the 1 to 10 GHz range using printed
circuit board techniques. This is due to its characteristic of the low dispersion

at high frequencies, and its ease of integration with other passive and active mi-

crowave devices. A microstrip line is characterized by the following geometrical

parameters: W (conductor line width), T (conductor thickness) and H (substrate
thickness). The microstrip line is implemented as a conductor bonded to a di-

electric substrate [32]. This substrate is characterized by its relative permittivity,

                                         65
r,   thickness, H and loss angle, tanδ. Since some of the fields generated by the

microstrip conductor exist in the air, the conductivity is also characterized by the
effective permittivity or effective dielectric constant,         e,   which is directly related
to W/H and              r.   The modes supported by microstrip lines are quasi-TEM due

the non simetrical structure of both the ground plane and the dielectric. It does
not support pure TEM waves since some of the field lines are in the air region

but most of them are in the dielectric region [26]. Figure 5.5 shows the field

distribution on a typical microstrip line.




                    Figure 5.5: Field Distribution of a Microstrip Line Section.


The substrate values used to simulate the filter prototypes is detailed below.

     1. H = 0.4mm. Substrate thickness.

     2.       r   = 3.84. Relative dielectric constant.

     3. M ur = 1. Relative permeatibility.

     4. Cond = 1.0e50 . Conductor conductivity.

     5. Hu = 1.0e33 . Cover height.

     6. T = 0.035mm. Conductor thickness.

     7. T anδ = 0.017. Dielectric loss tangent.

     8. Rough = 0mm. Conductor surface roughness.

     9. Substrate = F R4
          .




                                                 66
                       Figure 5.6: Substrate Parameters.


Some of the most common bandpass microstrip filters configurations are described
below:

  1. Direct Coupled Resonator : This filter configuration uses λ/4 resonators

     which are direct coupled using λ/4 transmission lines between adjacent

     resonators. The impedance inverters are part of the resonators themselves
     [31].

  2. Direct Parallel Coupled : Parallel coupled lines are the most common con-
     figuration used in microstrip filter design. However the lateral coupling

     between the lines generates small spacing and small width which cannot

     be accurately implemented. This is due to the nature of microstrip lines
     which are not homogeneous and causes inequality between odd and even
     mode phases [33]. This filter configuration uses λ/2 resonators with elec-
     tromagnetic coupling between λ/4 sections [26].Figure 5.7 illustrates this

     configuration.



                     Figure 5.7: Coupled Lines Layout.



  3. Hairpin:Hairpin filters are coupled line filters. The orientation of hairpin

     resonators alternates. This is because the electric and magnetic couplings
     tend to add, resulting in the maximum coupling for a given spacing between

     resonators. These have very similar characteristics to the parallel coupled
     line filter configuration.




                                       67
     The length of the micrstrip lines which join each parallel couple line section

     must at least λ/2 to avoid coupling between resonators. The filter configu-
     ration is shown in Figure 5.8.




                        Figure 5.8: Hairpin Layout.



  4. Combline Interdigital : This filter configuration uses λ/4 resonators which

     are grounded at opposite ends for adjacent resonator. There is electromag-
     netic coupling between resonators [26].

A small size filter is required for this platform. The area occupied by standard
couple line filters at these frequencies is too large. Normal hairpin structures
while occuping less space are still too large. For this platform a modified hairpin

structure is implemented. Simulation results have demonstrated that hairpin and

coupled line filters have very similar frequency response. Thus, the calculations

to generate parallel coupled line configurations are used to simulate the coupled
line filter and are implemented in a hairpin filter prototype. The next section

presents the design and simulations for the preselection filter using the equations

for microstrip lines and coupled line prototype filters.


Coupled Line Filter Theory

An N+1 coupled line bandpass filter is composed of N+1 admittance inverters,

J. Each coupled line corresponds to a transmission line network of -90o . The

equivalent model for each coupled line is shown in Figure 5.9. Impedance and
admittance inverters have the ability to transform series inductances to shunt ca-

pacitances and shunt capacitances to series capacitances. Thus, in this case the

                                        68
                Figure 5.9: Coupled Line Equivalent Prototype.


admittance inverters are separating parallel circuits. The admittance produced

from the J inverter can be defined as follows:

                                             J2
                                    Y =                                 (5.20)
                                             Y0

In order to calculate the parameter J for each network the equations below are
used [26]:


             J1   J7       πBw         πBw         J3   J5   πBw
                =    =         =           ;          =    = √          (5.21)
             Y0   Y0       2g1         2g1         Y0   Y0  2 g3 g5

                      J2   J6   J4   πBw      πBw
                         =    =    = √      = √                         (5.22)
                      Y0   Y0   Y0  2 g2 g1  2 g4 g3

Assuming a Z0 of 50Ω the corresponding even and odd impedances are obtained
[26]:
                                                2
                            Zoe = [1 + JZ0 + (JZ0 )]                    (5.23)

                                                2
                            Zoo = [1 − JZ0 + (JZ0 )]                    (5.24)



                 Zoe1 = Zoe7 = 1532;         Zoe2 = Zoe6 = 345          (5.25)

                      Zoe3 = Zoe5 = 97.68         Zoe4 = 72.93          (5.26)




               Zoo1 = Zoo7 = 1454.5;         Zoe2 = Zoe6 = 308.9        (5.27)

                         Zoe3 = Zoe5 = 78.99       Zoe4 = 56.94         (5.28)




                                        69
Using the impedances for each pair of coupled lines and knowing the charac-

teristic impedance of the line, the width, spacing and length can be calculated.
However due to the broadband characteristics of this filter and its expected low
insertion loss the obtained values for odd and even mode impedances in the two

outside coupled lines are particularly large of the orther of kohms. This results in
microstrip lines that are too narrow to manufacture. To solve this issue the filter

was redesigned without the requirement of 50Ω characteristic impedance in the

coupled line sections. However there are still some sections of the filter that are

not manufacturable. This filter is shown in Figure 5.11 and the corresponding

parallel coupled line model is shown in Figure 5.10. It can be seen for this figure




              Figure 5.10: 6th Order Parallel Coupled Line Filter.


that the two outer most sections have a spacing of less than 0.15 mm, which is the
minimum spacing that we can manufacture. The design was done for a 6th order

direct coupled line filter which results in 7 couple lines sections, N+1. The two
outer most coupled line sections were replaced with discrete component sections.

The spacing for the second outer most coupled line section was adjusted to 0.16

mm and the width of that coupled line reoptimized.




                                        70
              Figure 5.11: 6th Order Parallel Coupled Line Filter.


   This filter was then layed out in a modified hairpin configuration.         Fig-

ure 5.12 shows the filter layout. This layout was then simulated in ADS using




Figure 5.12: 6th Order Hairpin Filter with Passive Network Substituying First
and Last Sections .


co-simulation techniques for the coupled lines within ADS. The filter is built on
the FR4 0.4mm material. The filter response was then measured using a vector

network analyzer. Simulating and measured results are shown in Figure 5.13. It

is reflected in the input and output reflexion coefficients. The transfer character-
istic of the filter, S21, matches within 1.5dB. Similarly the reflection coefficient,

S11, matches also. Due to the losses in the used substrate the insertion loss of

the filter is approximately 5dB, while the lower edge of S11 is marginaly worse

than exopected. This can be improved with a lower loss substrate other than
FR4, such as RO4003 from the Rogers corporation.


                                       71
Figure 5.14 illustrates the implemented microstrip filter. The dimension of this
filter is 20mmx10mm.




    Figure 5.13: 6th Order Hairpin Filter: Simulations and Measurements.




                  Figure 5.14: Implemented Microstrip Filter.




5.5.2    Conclusion

This chapter has presented the design and implementation of the radio frequency
filter for this platform. The implemented design generates a filter response which

meets the specifications for the two test frequencies. In order to obtain a bet-
ter performance this final desgn still under development. The following section

describes the radio frequency amplification stage of the platform.


                                      72
Chapter 6

RF AMPLIFICATION


6.1     Introduction

In this chapter the transmitter and receiver RF amplification circuits are de-
scribed. In order to maximize the received and transmitted powers it is necessary

to match LNA and PA impedances to the antenna. This is achieved with a
matching network. In the case of the receiver the amplification circuit consists of
an LNA (low noise amplifier) device and external matching networks Similarly in

the case of the transmitter, this consists of a power amplifier(PA) chip and the

external matching networks along with a VGA (variable gain amplifier) to allow
transmitted power control.



6.2     Overview

The LNA was chosen for its linearity and low noise figure in the band of interest
while the PA was chosen for its efficiency and linearity. Both these ICs required

design of a suitable matching network. This is designed by representing the
reflected power at the input and output ports of the device using S (Scattering)

parameters and then selecting networks which minimize this reflected power. Any

N port network may be described by its N 2 S parameters. The S parameters relate

the incident voltage waves on the ports to those reflected from the ports of the


                                       73
network [26]. Thus, an example of an S parameter matrix is described below.

                                                                 
                     V1 −           S11   S12 . . . S1n        V1 +
                                                                 
                                                        +        
                  V2 −       S21 S12 . . . S2n           V2      
                                                                 
                  .        = .     .     .    .         .        
                  .          .     .     .    .         .        
                  .          .     .     .    .         .        
                                                                 
                   Vm −         Sm1 . . . . . . Smn           Vn +


Then, each element of the S matrix can be described as:

                                                Vm −
                                     Smn =                                     (6.1)
                                                Vn +

Where Vm − is the reflected voltage at the input port m and Vn + is the transmitted
voltage at the output port n. Hence, Smm is the reflection coefficient of each port
and Smn is the transmission coefficient from port m to port n. Therefore the

transmitted and reflected power can be calculated employing these coefficients
[26]. If the circuit is considered as a 2 port network,S11 , S22 , S12 , S21 are the
parameters to be measured, where:

   1. S11 : Input Return Loss

   2. S22 : Output Return Loss

   3. S12 : Isolation Coefficient

   4. S21 : Transmission Coefficient

S11 is a measure of the reflected power at the input. In order to achieve a good

match it is necessary to minimize S11 , and in doing so maximize the amount
of power entering the network. Similarly S22 measures the reflected power at

the output port. Minimizing this parameter maximizes the transmitted power
available at the antenna in the transmitter. S21 is representing the forward gain

in the network. In the case of an amplifier this is its gain. S12 represents the
transmitted power from the output to the input of the network. If the network

is reciprocal S12 = S21 .

                                           74
The design of the matching network for the LNA is particularly complicated.
This is due to the fact that the LNA also requires optimum input impedances

for maximum signal power transform and minimum self noise generation. Due
to this, a no conjugated matching network in the input and output port may

provide the best trade-off between gain and noise figure.



On the other hand, for the transmitter maximum power is required. Thus con-
jugated impedance matching at the input and output of the PA is needed. The

maximum available gain, MAG, which can be attained under conjugated condi-

tions. MAG is described below [26].

                                  | S21 |             √
                  M AG = 10 log           + 10 log K − K 2 − 1            (6.2)
                                  | S12 |

Where K is stability factor of the amplifier given by:


                           a = S22 S11                                    (6.3)

                           b = S12 S21                                    (6.4)

                           ∆=a−b                                          (6.5)
                                1 − |S11 |2 − |S22 |2 + |∆|2
                           K=                                             (6.6)
                                          2S11 S22

The amplifier is unconditionally stable for K > 1. Figure 6.1 illustrates the

matching network configuration for a 2-port network. In order to obtain a con-
jugate match, ρ1 has to be the complex conjugated of Γin . Equally ρ2 has to

be the complex conjugated of Γout , where Γin and Γout are the input and output




                        Figure 6.1: Matching Networks.


                                         75
reflexion coefficients respectively, and are given by equations 6.7 and 6.8:

                                            S12 S21 ρ2
                             Γin = S11 +                                     (6.7)
                                            1 − S22 ρ2

                                            S12 S21 ρ1
                             Γout = S22 +                                    (6.8)
                                            1 − S11 ρ1

where the reflexion coefficients are defined as the amplitude of the reflected volt-
age wave normalized to the amplitude of the incident voltage wave [26].



6.3     Low Noise Amplifier

6.3.1    Specifications

The LNA as its name suggests is an amplifier with a very low noise figure. From

the point of view of the Friis equation the LNA has the greatest effect on the

total noise figure of the system since it is the first amplification stage of the
signal. Consequently the noise figure of the LNA must be kept to the minimum
possible. The noise figure of the LNA and the thermal noise at the antenna
define the sensitivity of the system. The LNA must provide enough gain to allow

the mixer to demodulate the required reference sensitivity signal. The output of
the LNA must be within the dynamic range of the input of the mixer to avoid

amplitude mismatch. In this way the signal, after the downconversion stage, will

have large enough amplitude for the required dynamic range of the ADC’s. The

LNA is specified by the following parameters:

  1. Gain: It is the ratio between the output power and the input power in the

      LNA.

  2. Noise figure: It is the ratio between the output SNR and the input SNR.
      It is a measure of the noise contributed by the LNA.

  3. Linearity: The ability of the amplifier to linearly increase the output signal

      in line with the input signal. The gain of the amplifier drops off for larger

                                       76
     input signal causing distortion. This effect is characterized by the IIP3 and

     3dB gain compression point.

  4. Input impedance: This is the impedance seen looking into the input port
     of the amplifier with a loaded output.

  5. Dissipated power: This is the difference between the DC power inputted
     and the RF power outputted. This depend of the architecture and technol-

     ogy used in its implementation.

The required values for these parameters have been given in chapter 3. This

influences in the performance of the rest of the system. The bandwidth of the

LNA amplifier must also meet the bandwidth requirements of the receiver. As
previously stated the maximum gain with minimum noise is required from the
LNA. Generally the maximum gain and minimum noise do not occur at the same
operating point. For this reason a compromise is reached where an operating
point is chosen to give the best SNR and linearity at the output of the LNA.

Device manufacturers publish noise and gain circles to facilitate this.


Design and Implementation

The chosen LNA was the Freescale Semiconductor MBA13720. This device fea-

tures a gain of approximately 12dB with an optimum noise figure of 1.55dB. It
works in a frequency range from 400 MHz to 2.4 GHz. The LNA can work in three

modes: bypass, low IP3 and high IP3 modes [34]. Generally, the best noise figure

is achieved working in the low IP3 mode although the high IP3 mode achieves a
better gain but only by 1 dB. The LNA has a bypass switch which may be used to

minimize the loss between bypass and amplifier modes. The LNA S parameters




                                        77
at 2.35 GHz are as follows [34].


                                   S11 = 0.4479∠−470                         (6.9)

                                   S12 = 0.1494∠810                         (6.10)

                                   S21 = 3.322∠66.20                        (6.11)

                                   S22 = 0.6082∠−38.40                      (6.12)




In order to ensure unconditional stability | Γin |< 1 and | Γout |< 1. Therefore

the stability of the LNA also depends on the external matching networks. Since
the stability conditions of a network are frequency dependent [26], the amplifier
may be perfectly stable at the working frequencies and unstable at surrounding

frequencies. Stability circles may be used to plot the regions of stable operation

on the Smith chart. Alternatively the stability factor K can be defined as it is
given in 6.13below [35].

                                   1 − |S11 |2 − |S22 |2 + |∆|2
                           K=                                               (6.13)
                                             2S11 S22
                           a = S22 S11                                      (6.14)

                           b = S12 S21                                      (6.15)

                           ∆=a−b                                            (6.16)

                           LN AK = 1                                        (6.17)

                                                                            (6.18)


where LN AK is called the Linvill stability factor with the matching networks
shown Figures 6.2. For unconditionally stable operation the parameters must

achieve: K ≥ 1 [26]. However in this case the amplifier is working in its condi-

tionally stable zone because K = 1.


Figure 6.2 gives the diagram of the implemented LNA circuit including the match-


                                          78
ing elements. Figure 6.3 gives the simulated response of this circuit. It can be

seen from Figure 6.3 that the gain at 2.08GHz is approximately 12dB while the
return loss is approximately -13dB. The gain drops to 10dB at 2.35GHz while the
return loss is approximately -12dB.




                               Figure 6.2: LNA.




                           Figure 6.3: LNA Respond.




6.4     Power Amplification Stage

Due to the requirements to support a variety of protocols high linearity together
with a large output power range are needed. For this reason the power ampli-

fication stage consists of a VGA, variable gain amplifier, under software control
followed by a fixed gain PA. This configuration offers the best flexibility and

efficiency compromise.

                                       79
Design and Implementation

The implemented PA in the platform is a broadband GaAs power amplifier, which

works in the frequency band from 500 MHz to 6 GHz. This is the Agilent part
MGA-83563. This device generates an efficiency figure for maximum output
power of 37%, which meets the specifications. In addition the isolation produced

by the PA is approximately -38 dB. Figure 6.4 illustrates the PA design. The

input to this PA is power controlled by a VGA, which features a gain from -40dB

to 16 dB in a voltage range from 0V to 1.4V at its input.


The VGA device is the Analog Devices ADL5300. It is a high linearity am-
plifier which performs a linear-in-dB amplification with a gain control slope of

20mV/dB. The maximum input voltage is 1.4 V which generates a maximum
gain of approximately 20dB. The minimum input voltage is 0.2 which results in a
gain of -40dB. The device is able to operate up to 3GHz. The output impedance
of the VGA is 50 ohm in order to match the input impedance of the PA.



In order to calculate the external matching networks for the PA, the internal
S parameters described below are used.


                                 S11 = 0.40∠−360                         (6.19)

                                 S12 = 0.024∠680                         (6.20)

                                 S21 = 11.07∠−820                        (6.21)

                                 S22 = 0.49∠−1750                        (6.22)


The resulting external matching networks are presented in Figure 6.4. This is
achieved with a combination of microstrip lines and discrete components. This

model has been simulated in the ADS simulation environment to obtain the gain

response and linearity of the amplifier shown in Figure 6.5. The gain on the
PA is flat across the band of frequencies of interest at approximately 24dB. The


                                      80
return loss is less than -20dB across the band of interest. Analysis of PA stability

is carried out in the same way as for the LNA. The equations below present the
calculations for the stability factor [35].


                             a = S22 S11                                     (6.23)

                             b = S12 S21                                     (6.24)

                             ∆=a−b                                           (6.25)
                                              2     2          2
                                   1 − |S11 | − |S22 | + |∆|
                             K=                                              (6.26)
                                             2S11 S22
                             P AK = 1.5469                                   (6.27)


where P AK is called the Linvill stability factor. For unconditionally stable op-

eration the parameters must achieve: P AK ≥ 1 [26]. It can be seen from Equa-
tion 6.27 that the amplifier is working in a stable regime. According to that, the
PA is stable in its corresponding working frequencies.




                            Figure 6.4: Power amplifier.




                            Figure 6.5: Power amplifier.


                                           81
6.5     Conclusion

The implemented designs of the LNA and PA are described in detail in this chap-

ter. The circuit’s topologies and components values for the matching networks
of the amplifiers are presented. The simulated performance of both implementa-
tions is given including stability calculations and the resulting complete circuit

diagrams are given.




                                       82
Chapter 7

CONSTRUCTION AND
TESTING OF THE
RECONFIGURABLE RADIO
TESTBED


7.1     Introduction

This chapter presents some of the details of the physical implementation for this

platform followed by some operational examples. An overview of the materials

and technology used in the construction of the board is given. Some of the

implementation problems overcome during fabrication are detailed. It gives an

overview about the available technology used for the realization of the software

defined radio system. It presents as well, some of the implementation issues during
the fabrication. Schematics and layouts for receiver, transmitter and baseband

board are shown. Some test results detailing the performance of the system are

given. Finally some plots resulting from the Matlab implemented software are
given at the end of this chapter.




                                       83
7.2     Devices and Equipment

A variety of equipment and technologies are used in this platform. The integrated

circuits are implemented using CMOS, BICMOS and GaAs semiconductor tech-
nologies. Standard PCB (printed circuit board) techniques are used to construct
the prototypes with additional microstrip technique for certain elements of the

design. Table 7.1 presents a list of the integrated circuits used in the signal and
control paths. In the table part number, manufacturer, package, and frequency

range are given. Details of the system level layout of these components are given
in Figure 4.1 in chapter 4.



                      Table 7.1: Commercial devices used




Surface mount technology, SMT, is used exclusively in the construction of the
platform. The principal advantages of SMT over through hole techniques are [1]:

smaller components, placement of components over the two sides of the board

and better mechanical performance. The main disadvantage of SMT technol-
ogy is component handling. While SMT facilitates the construction of smaller

systems, this is achieved using smaller device packages. As the package size is

                                        84
reduced these devices become more difficult to accurately mount and test.



7.3      Materials

The implementation of the whole system is realized using PCB technology. This

consists of metal layers separated by a dielectric. The dielectric used for the base-
band PCBs is FR4 (flame-retardardant formulation number 4). FR4 consists of
glass fibre woven material impregnated with epoxy resin. It is specified by its me-

chanical strength, dielectric breakdown voltage, dielectric constant and dielectric

loss angle. Standard FR4 material has a dielectric constant of 4.2, however this

changes with frequency. Also the dielectric loss displays a linear increase with
frequency in this material. Typically FR4 exhibits a loss of 0.03dB/cm/GHz for
microstrip lines implemented with 1.6mm thick material. This implies a constant

loss per wavelength at any frequency of 0.5dB/wavelength [32]. While this has
little or no bearing on sub GHz operation, it has significant affect at the frequen-
cies of our design. Where RF signals are concerned the PCB traces are designed
as controlled impedance lines. The principle type of controlled impedance line

implemented in this design is a microstrip line. The performance of the microstrip
line is affected by the physical and electrical characteristics of both the dielectric
and conductor materials. Poor design of the transmission lines for the desired fre-

quency will result in impedance mismatches which will generate reflected power,

reducing the overall SNR of the system.


Due to the loss nature of FR4, in order to reduce the losses at RF frequen-

cies a smaller thickness material is used. In this case 0.4mm thick FR4 is used.

This is possible as the RF boards are implemented separately from the basband
board.




                                         85
7.3.1    Implementation Problems

The RF connections are implemented using microstrip lines. Some of the main

qualities of microstrip lines are: small dimension, low cost production, wide range
of characteristic impedance and working frequencies up to 110 GHz. However
this technology has the disadvantage of high loss due to the skin effect, radiation

losses, conductor losses and dielectric losses. The skin effect is the tendency

of the current to flow on the surface of the conductor as the signal frequency

increments [26]. Also, due to the structure of microstrip lines they do not exhibit

a true TEM transmission mode so the design equations are empirical. For these
reasons electromagnetic modelling of these structures is necessary. This was done
using the electromagnetic 2.5D solver, Momentum from Agilent. This allows us

to identify and avoid such a problems as: EMI(electromagnetic interference),
capacitive coupling (cross talk), collapsed feed lines (Rail collapse), substrate
coupling and reflexions due to bad matching. Figure 7.1 shows some of these
principal issues generated in the implementation of RF systems.




                         Figure 7.1: Distortion Sources.


These problems are solved with the addition of suitable filters and careful circuit

layout. For instance to decrease the noise at the output of the DC converter a

π section noise filter is used. In addition, in the RF receiver and transmitter a

metal can is place around various sections such as the LNA and VCO to provide
screening which increases the isolation between parts. This also improves the


                                        86
SNR by shielding sensitive components from outside noise.



7.4     Platform Schematics and Layouts

7.4.1    Baseband board

Figure 7.2 and Figure 7.3 illustrates the circuit diagram of the baseband board.

The computer connection is made over the USB bus to the Cypress chip

CY7C68013. This chip connects through latches to the ADCs and the DACs.

It also provides the 8 bit address and data bus for controlling the transmitter
and receiver boards. The sampling frequency generation is controlled by the i2 C

interface of this chip. The sampling frequency generation is achieved using the
Cypress CY22393 chip, which is controlled by the i2 C interface of the USB chip.
The layout of this board is shown in Figure 7.4.




7.4.2    Transmitter board

Figure 7.5 and Figure 7.6 illustrates the schematic of the transmitter board. The
transmitter board is connected to the baseband board by a signal interface and

a control interface. The control interface is made of 8 address and 8 data lines.
These 8 address digital signals are connected to a comparator (74HCT688). When

this comparator is addressed it enables the latch (LVC573). This latch passes the

data to the DAC (AD7801). The DAC output forms the analog voltage input

to the VGA (ADL5300) gain control. This mechanism provides software control
of the transmitter power gain. A second comparator is used together with a

second latch to provide control of the synthesizer and the modulator. In this way
software control of the LO frequency and of the modulator is provided.

Power is provided over the control link for the board. Four different supplies are
required on the board: 2.5V, 3.3V, 5V and -5V. These are generated on-board

using linear voltage regulators. A switch mode voltage inverter is used for the

                                       87
                                                                                                                                                                                                                                                                           P$75                                              P$74
                                                                                                                                                                                                                                                                                    2OE                              2LE
                                                                                                                                                                                                                                                                           P$83                                              P$73
                                                                                                                                                                                                                                                                                    2Q8                              2D8
                                                                                                                                                                                                                                                                           P$82                                              P$72
                                                                                                                                                                                                                                                                                    2Q7                              2D7
                                                                                                                                                                                                                                                                           P$87                                              P$88
                                                                                                                                                                                                                                                                                    GND4                           GND5
                                                                                                                                                                                                                                                                           P$81                                              P$71
                                                                                                                                                                                                                                                                                    2Q6                              2D6
                                                                                                                                                                                                                                                                           P$80                                              P$70
                                                                                                                                                                                                                                                                                    2Q5                              2D5
                                                                                                                                                                                                                                                                           P$94                                              P$95
                                                                                                                                                                                                                                                                                    VCC1                           VCC2
                                                                                                                                                                                                                                                                           P$79                                              P$69
                                                                                                                                                                                                                                                                                    2Q4            74LVCH16373A      2D4
                                                                                                                                                                                                                                                                           P$78                                              P$68
                                                                                                                                                                                                                                                                                    2Q3                              2D3




                                                                                   P$34
                                                                                                 P$33
                                                                                                                 P$32
                                                                                                                                     P$30
                                                                                                                                                    P$29
                                                                                                                                                                    P$28
                                                                                                                                                                                   P$27
                                                                                                                                                                                                 P$26
                                                                                                                                                                                                               P$22
                                                                                                                                                                                                                             P$21
                                                                     P$35                                                                                                                                                                                                  P$86                                              P$89
                                                                                         35                                                                                                                                                                                         GND3                           GND6
                                                                                                                                                                                                                                           P$15
                                                                                                                                                                                                          OGND3




                                                                                                                                                                                                                               21




                                                                                     34
                                                                                                    33
                                                                                                                    32
                                                                                                                                       30
                                                                                                                                                       29
                                                                                                                                                                       28
                                                                                                                                                                                     27
                                                                                                                                                                                                   26
                                                                                                                                                                                                                 22
                                                                     P$39                                                                                                                                                                  P$23                            P$77                                              P$67
                                                                                         39                                                                                                               OGND2                                                                     2Q2                              2D2
                                                                                                                                                                                                                                           P$24
                                                                                                                                                                                                          OGND1
                                                                     P$40                                                                                                                                                                  P$25                            P$76                                              P$66
                                                                                         40                                                                                                                OGND                                                                     2Q1                              2D1
                                                                                                                                                                                                                                           P$31
                                                                                                                                                                                                           GND4
                                                                     P$41                                                                                                                                                                  P$36                            P$65                                              P$56
                                                                                         41                                                                                                                GND3                                                                     1Q8                              1D8
                                                                                                                                                                                                                                           P$37
                                                                                                                                                                                                           GND2




                                                                                                                                                                                                                                                            GND
                                                                     P$42                                                                                                                                                                  P$38                            P$64                                              P$55
                                                                                         42                                                                                                                GND1                                                                     1Q7                              1D7
                                                                                                                                                            ADC                                                                            P$48
                                                                                                                                                                                                            GND
                                                                     P$43                                                                                                                                                                                                  P$85                                              P$90
                                                                                         43                                                                                                                                                                                         GND2                           GND7
                                                                                                                                                                                                                                           P$11
                                                                                                                                                                                                           OVDD3
                                                                     P$44                                                                                                                                                                  P$12                            P$63                                              P$54
                                                                                         44                                                                                                                OVDD2                                                                    1Q6                              1D6




                                       10k
                                                                                                                                                                                                                                           P$13
                                                                                                                                                                                                           OVDD1




                                               R20A
                                                                     P$45                                                                                                                                                                  P$14                            P$62                                              P$53
                                                                                         45                                                                                                                 OVDD                                                                    1Q5                              1D5
                                                                                                                                                                                                                                           P$3
                                                                                                                                                                                                            VDD4
                                                                     P$46                                                                                                                                                                  P$4                             P$93                                              P$96
                                                                                         46                                                                                                                 VDD3                                                                    VCC                            VCC6




                                       10k
                                                                                                                                                                                                                                           P$5
                                                                                                                                                                                                            VDD2
                                                                     P$47                                                                                                                                                                  P$8                             P$61                                              P$52




                                                               GND




                                               R20A1
                                                                                         47                                                                                                                 VDD1                                                                    1Q4                              1D4
                                                                            C49A                                                                                                                                                           P$9




                                                                                     1
                                                                                                    2
                                                                                                                    6
                                                                                                                                       7
                                                                                                                                                       10
                                                                                                                                                                       16
                                                                                                                                                                                     17
                                                                                                                                                                                                   18
                                                                                                                                                                                                                 19
                                                                                                                                                                                                                               20
                                                                                                                                                                                                             VDD
                                                                                                                                                                                                                                                                           P$60                                              P$51
                                                                                                                                                                                                                                                                                    1Q3                              1D3
                                                                            0.1uF
                                                                                                                                                                                                                                                                           P$84                                              P$91
                                                                                                                                                                                                                                                                                    GND                            GND11




                                                                                                 P$2
                                                                                                                 P$6
                                                                                                                                     P$7
                                                                                                                                                    P$10
                                                                                                                                                                    P$16
                                                                                                                                                                                   P$17
                                                                                                                                                                                                 P$18
                                                                                                                                                                                                               P$19
                                                                                                                                                                                                                             P$20




                                                                             10k P$1
                                                                                                                                                                                                                                                                           P$59                                              P$50




                                                                             +3V3
                                                                                                                                                                                                                                                                                    1Q2                              1D2




                                                                                           R19A
                                                                                                                                                                                                                                                                           P$58                                              P$49
                                                                                                                                                                                                                                                                                    1Q1                              1D1




                                                                                                             VcM
                                                                                                                                                                                                                                                                           P$92                                              P$57
                                                                                                                                                                                                                                                                                    OE                               1LE




                                                                                                                                                                                                                                                            C51A

                                                                                                                                                                                                                                            100pF
                                                                                                                                                                                                                                                                                                                                      GND




                                                                                          C55A
                                                                                                         100pF
                                                                                                                                            C56A
                                                                                                                                                            100pF
                                                                                                                                                                                                                                                      I9




                                                                                                                                                                                   GND
                                                                                                                                                                                                                                           10k




                                                                             GND
                                                                                                                                                                                                                                                        VcM




                                                                                                                                        output-

                                                                                                                 output+




                                  88
                                                                                                                                                                                                                                                                                            +3V3
                                                                                                                                                                                                                                                                             P$75                                              P$74
                                                                                                                                                                                                                                                                                     2OE                               2LE
                                                                                                                                                                                                                                                                             P$83                                              P$73
                                                                                                                                                                                                                                                                                     2Q8                               2D8
                                                                                                                                                                                                                                                                             P$82                                              P$72
                                                                                                                                                                                                                                                                                     2Q7                               2D7
                                                                                                                                                                                                                                                                             P$87                                              P$88
                                                                                                                                                                                                                                                                                     GND4                            GND5
                                                                                                                                                                                                                                                                             P$81                                              P$71
                                                                                                                                                                                                                                                                                     2Q6                               2D6
                                                                                                                                                                                                                                                                             P$80                                              P$70
                                                                                                                                                                                                                                                                                     2Q5                               2D5
                                                                                                                                                                                                                                                                             P$94                                              P$95
                                                                                                                                                                                                                                                                                     VCC1                            VCC2
                                                                                                                                                                                                                                                                             P$79                                              P$69
                                                                                                                                                                                                                                                                                     2Q4            74LVCH16373A       2D4
                                                                                                                                                                                                                                                                             P$78                                              P$68
                                                                                                                                                                                                                                                                                     2Q3                               2D3




                                                                                          P$34
                                                                                                         P$33
                                                                                                                           P$32
                                                                                                                                            P$30
                                                                                                                                                            P$29
                                                                                                                                                                            P$28
                                                                                                                                                                                          P$27
                                                                                                                                                                                                        P$26
                                                                                                                                                                                                                      P$22
                                                                                                                                                                                                                                    P$21




Figure 7.2: Baseband schematic.
                                                                           P$35                                                                                                                                                                                              P$86                                              P$89
                                                                                              35                                                                                                                                                                                     GND3                            GND6
                                                                                                                                                                                                                                                 P$15
                                                                                                                                                                                                                 OGND3




                                                                                                                                                                                                                                      21




                                                                                            34
                                                                                                            33
                                                                                                                              32
                                                                                                                                              30
                                                                                                                                                               29
                                                                                                                                                                              28
                                                                                                                                                                                            27
                                                                                                                                                                                                          26
                                                                                                                                                                                                                        22
                                                                           P$39                                                                                                                                                                  P$23                        P$77                                              P$67
                                                                                              39                                                                                                                 OGND2                                                               2Q2                               2D2
                                                                                                                                                                                                                                                 P$24
                                                                                                                                                                                                                 OGND1
                                                                           P$40                                                                                                                                                                  P$25                        P$76                                              P$66
                                                                                              40                                                                                                                  OGND                                                               2Q1                               2D1
                                                                                                                                                                                                                                                 P$31
                                                                                                                                                                                                                  GND4
                                                                           P$41                                                                                                                                                                  P$36                        P$65                                              P$56
                                                                                              41                                                                                                                  GND3                                                               1Q8                               1D8
                                                                                                                                                                                                                                                 P$37
                                                                                                                                                                                                                  GND2




                                                                                                                                                                                                                                                                   GND
                                                                           P$42                                                                                                                                                                  P$38                        P$64                                              P$55
                                                                                              42                                                                                                                  GND1                                                               1Q7                               1D7
                                                                                                                                                                                                                                                 P$48
                                                                                                                                                                                                                   GND
                                                                           P$43                                                                                                                                                                                              P$85                                              P$90
                                                                                              43                                                                                                                                                                                     GND2                            GND7
                                                                                                                                                  ADC                                                                                            P$11
                                                                                                                                                                                                                  OVDD3
                                                                           P$44                                                                                                                                                                  P$12                        P$63                                              P$54
                                                                                              44                                                                                                                  OVDD2                                                              1Q6                               1D6




                                             10k
                                                                                                                                                                                                                                                 P$13
                                                                                                                                                                                                                  OVDD1
                                                                           P$45                                                                                                                                                                  P$14                        P$62                                              P$53




                                                       R20A2
                                                                                              45                                                                                                                   OVDD                                                              1Q5                               1D5
                                                                                                                                                                                                                                                 P$3
                                                                                                                                                                                                                   VDD4
                                                                           P$46                                                                                                                                                                  P$4                         P$93                                              P$96
                                                                                              46                                                                                                                   VDD3                                                              VCC                             VCC6




                                             10k
                                                                                                                                                                                                                                                 P$5
                                                                                                                                                                                                                   VDD2
                                                                           P$47                                                                                                                                                                  P$8                         P$61                                              P$52




                                                                     GND




                                                       R20A3
                                                                                              47                                                                                                                   VDD1                                                              1Q4                               1D4
                                                                               C49A1                                                                                                                                                             P$9




                                                                                            1
                                                                                                            2
                                                                                                                              6
                                                                                                                                              7
                                                                                                                                                               10
                                                                                                                                                                              16
                                                                                                                                                                                            17
                                                                                                                                                                                                          18
                                                                                                                                                                                                                        19
                                                                                                                                                                                                                                      20
                                                                                                                                                                                                                    VDD
                                                                                                                                                                                                                                                                             P$60                                              P$51
                                                                                                                                                                                                                                                                                     1Q3                               1D3
                                                                               0.1uF
                                                                                                                                                                                                                                                                             P$84                                              P$91
                                                                                                                                                                                                                                                                                     GND                            GND11




                                                                                                         P$2
                                                                                                                           P$6
                                                                                                                                            P$7
                                                                                                                                                            P$10
                                                                                                                                                                            P$16
                                                                                                                                                                                          P$17
                                                                                                                                                                                                        P$18
                                                                                                                                                                                                                      P$19
                                                                                                                                                                                                                                    P$20




                                                                                   10k P$1
                                                                                                                                                                                                                                                                             P$59                                              P$50




                                                                                   +3V3
                                                                                                                                                                                                                                                                                     1Q2                               1D2




                                                                                                   R19A1
                                                                                                                                                                                                                                                                             P$58                                              P$49
                                                                                                                                                                                                                                                                                     1Q1                               1D1




                                                                                                                      VcM
                                                                                                                                                                                                                                                                             P$92                                              P$57
                                                                                                                                                                                                                                                                                     OE                                1LE




                                                                                                                                                                                                                                                    100pF
                                                                                                                                                                                                                                                                   C51A1




                                                                                                 C55A1
                                                                                                                 100pF
                                                                                                                                                   C56A1
                                                                                                                                                                    100pF
                                                                                                                                                                                                                                                             I1




                                                                                                                                                                                          GND
                                                                                                                                                                                                                                                 10k




                                                                                   GND
                                                                                                                                                                                                                                                               VcM




                                                                                                                                                  output-

                                                                                                                           output+
                                                                                                                                                                                                                                                                                                                                      GND
                                                                                                                                                                                                                                                                                                                                                                                                                                  24lc64




                                                                                                                                                                    GND
                                                                                                                                                                                                                                                                                                                                                                                                                         P$9                        P$7
                                                                                                                                                                                                                                                                                                                                                                                                                                P$9        P$7
                                                                                                                                                                                                                                                                                                                                                                                                                         P$10                       P$8
                                                                                                                                                                                                                                                                                                                                                                                                                                P$10       P$8




                                                                                                                                     5
                                                                                                                                                                                                                                                                                                                                                                                                                         P$11                       P$6
                                                                                                                                                                                                                                                                                                                                                                                                                                P$11       P$6
                                                                                                                      8                                 4




                                                                                                                                                                                                                                                                                                                                                                                                                   GND




                                                                                                                                                  GND




                                                                                                                            VCC
                                                                                                                                      SDA
                                                                                                                                                                                                                                                                                                                                                                                                                         P$12                       P$5
                                                                                  +3V3                                                                                                                                                                                                                                                                                                                                          P$12       P$5
                                                                                                                                      Array
                                                                                                                                   EEPROM                                                                                                                                                                                                                                                                                P$13                       P$4
                                                                                                                                                                                                                                                                                                                                                                                                                                P$13       P$4
                                                                                                                                                                                                                                                                                                                                                                                                                         P$14                       P$3
                                                                                                                                                                                                                                                                                                                                                                                                                                P$14       P$3




                                                                                                                                                                                                                                                                                                                                                                                                                                                            GND




                                                                                                                             SCL
                                                                                                                                      A2
                                                                                                                                      A1
                                                                                                                                      A0
                                                                                                                                                                                                                                                                                                                                                                                                                                                        +3V3




                                                                                                                    IC2
                                                                                                                                                        24-LC65SM
                                                                                                                                                                                                                                                                                                                                                                                                                         P$15                       P$2




                                                                                                                                     1
                                                                                                                                                                                                                                                                                                                                                                                                                                P$15       P$2




                                                                                                                            6
                                                                                                                                     3
                                                                                                                                     2
                                                                                                                                                                                                                                                                                                                                                                                                                     +3V3
                                                                                                                                                                                                                                                                                                                                                                                                                      P$16                          P$1
                                                                                                                                                                                                                                                                                                                                                                                                                                P$16       P$1




                                                                                                                                                                                                                                                                                                                                                                                                                                                        2




                                                                                                                                                        d7
                                                                                                                                                        d6
                                                                                                                                                        d5
                                                                                                                                                        d0
                                                                                                                                                        d1
                                                                                                                                                        d2
                                                                                                                                                        d3
                                                                                                                                                        d4
                                                                                                                                                                                                                                            a7
                                                                                                                                                                                                                                            a6
                                                                                                                                                                                                                                            a5
                                                                                                                                                                                                                                            a4
                                                                                                                                                                                                                                            a3
                                                                                                                                                                                                                                            a2
                                                                                                                                                                                                                                            a1
                                                                                                                                                                                                                                            a0
                                                                                                                                                                                                                                                                                                                                                                                                                                                 IC1A
                                                                                                                                                                                                                                                                                                                                                                                                                                                            4069D




                                                                                                      2k2


                                                                                     R3A
                                                                                            2k2 R4A
                                                                                                                                                                                                                                                                                                                                                                                                                                                        1
                                                                                                                                   GND

                                                                                                                                                                                                                                                                                                                                                                                                                                             74HC1G04




                                                                                                                     37
                                                                                                                     36
                                                                                                                                    53
                                                                                                                                    52
                                                                                                                                    51
                                                                                                                                    50
                                                                                                                                                        88
                                                                                                                                                        87
                                                                                                                                                        86
                                                                                                                                                        63
                                                                                                                                                        62
                                                                                                                                                        61
                                                                                                                                                        60
                                                                                                                                                        59
                                                                                                                                                                                                            25
                                                                                                                                                                                                            24
                                                                                                                                                                                                            23
                                                                                                                                                                                                            22
                                                                                                                                                                                                            21
                                                                                                                                                                                                            128
                                                                                                                                                                                                            127
                                                                                                                                                                                                            126
                                                                                                                                                                                                            120
                                                                                                                                                                                                            119
                                                                                                                                                                                                            118
                                                                                                                                                                                                            117
                                                                                                                                                                                                            97
                                                                                                                                                                                                            96
                                                                                                                                                                                                            95
                                                                                                                                                                                                            94
                                                                         108
                                                                               108PE0/T0OUT




                                                                                                                                                                                                                95A1




                                                                                                                                                            60D1
                                                                                                                                                                                                                97A3
                                                                                                                                                                                                                96A2
                                                                                                                                                                                                                94A0




                                                                                                                                                            88D7
                                                                                                                                                            67D6
                                                                                                                                                            86D5
                                                                                                                                                            63D4
                                                                                                                                                            62D3
                                                                                                                                                            61D2
                                                                                                                                                            59D0
                                                                                                                                                                                                               21A11
                                                                         109




                                                                                                                                                                                                               25A15
                                                                                                                                                                                                               24A14
                                                                                                                                                                                                               23A13
                                                                                                                                                                                                               22A12
                                                                                                                                                                                                               127A9
                                                                                                                                                                                                               126A8
                                                                                                                                                                                                               119A6
                                                                                                                                                                                                               118A5
                                                                                                                                                                                                               117A4




                                                                                                                          36SCL
                                                                                                                          37SDA
                                                                               109PE1/T1OUT




                                                                                                                                    52TXD1
                                                                                                                                                                                                              120AA7




                                                                                                                                    53RXD1
                                                                                                                                    50TXD0
                                                                                                                                    51RXD0
                                                                                                                                                                                                                                                                                                   GND




                                                                                                                                                                                                             1128A10
                                                                         110
                                                                               110PE2/T2OUT                                                                                                                                                                                                      10k
                                                                         111                                                                                                                                                                                            35
                                                                               111PE3/RXD0OUT                                                                                                                                                              35EA
                                                                         112                                                                                                                                                                                            38
                                                                               112PE4/RXD1OUT                                                                                                                                                             36DE#                                  R6A
                                                                         113                                                                                                                                                                                            42
                                                                               113PE5/INT6                                                                                                                                                                42CS#
                                                                         114                                                                                                                                                                                            41
                                                                               114PE6/T2EX                                                                                                                                                                41WR#
                                                                         115                                                                                                                                                                                            40
                                                                               115PE7/GPIFADR8                                                                                                                                                            40RD#
                                                                                                                                                                                                                                                                        39
                                                                                                                                                                                                                                                        39PSEN#
                                                                         124
                                                                               124PD7/FD15                                                                                                                                                                                                                     GND
                                                                         123                                                                                                                                                                                            34
                                                                               123PD6/FD14                                                                                                                                                                 BKPT                                        10k
                                                                         122                                                                                                                                                                                            33
                                                                               122PD5/FD13                                                                                                                                                             RESERVED                         10k
                                                                         121                                                                                                                                                                                            32
                                                                               121PD4/FD12                                                                                                                                                               32IFCLK                                       R5A
                                                                         105                                                                                                                                                                                            31
                                                                               105PD3/FD11                                                                                                                                                                  31T2                       R28A                                                                                       GND
                                                                         104                                                                                                                                                                                            30
                                                                               104PD2/FD10                                                                                                                                                                   30T1
                                                                         103                                                                                                                                                                                            29
                                                                               103PD1/FD9                                                                                                                                                                   29T0
                                                                         102                                                                                                                                                                                            28                                                                                                       1uF
                                                                               102PD0/FD8                                                                                                                                                                 28INT4                                10k
                                                                                                                                                                                                                                                                        106                                                                                                                    1               4

                                                                                                                                                                                                                                                                                                                                                                                                          ON
                                                                                                                                                                                                                                                        106INT5#
                                                                         79                                                                                                                                                                                                                                                                                                 C20A               2               3




                                                                                                                                                                                                                                                                                                                                                                                                   2 1
                                                                               79PC7/GPIFADR7                                                                                                                                                                                              R27A                                         GNDX1
                                                                         78                                                                                                                                                                                             99
                                                                               78PC6/GPIFADR6                                                                                                                                                        99RESET#
                                                                         77                                                                                                                                                                                             101                                                                        1                                                     SW1




                                                                                                                                                                                                                                                                                                                                                                                         R2A
                                                                               77PC5/GPIFADR5                                                                                                                                                      101*WAKEUP




                                                                                                                                                                                                                                                                                                                                                                                  100k
                                                                         76                                                                                                                                                                                             19                                                                         2                                           +3V3
                                                                               76PC4/GPIFADR4                                                                                                                                                        19DMINUS                                                                                                             R1A
                                                                         75                                                                                                                                                                                             18                                                                         3
                                                                               75PC3/GPIFADR3                                                                                                                                                         18DPLUS




                                                                                                                                                                                                                                                                                                                                                       USB
                                                                         74                                                                                                                                                                                                                                                                        4             10uF
                                                                               74PC2/GPIFADR2                                                                                                                                                                                                                                                                             100k
                                                                         73                                                                                                                                                                                             16
                                                                               73PC1/GPIFADR1                                                                                                                                                               16NC
                                                                         72                                                                                                                                                                                             15                                                                                       C19A
                                                                               72PC0/GPIFADR0                                                                                                                                                               15NC
                                                                                                                                                                                                                                                                        14




                                                                                                                                                                                                                                                                                                                                C44
                                                                                                                                                                                                                                                                                                                                      12p
                                                                                                                                                                                                                                                            14NC
                                                                         57
                                                                               57PB7/FD7                                                                                         CY7C68013A




                                                                                                                                                                                                                                                                                                                  1
                                                                         56                                                                                                                                                                                             12                                                                                          GND




                                                                                                                                                                                                                                                                                                                        Q2
                                                                               56PB6/FD6                                                                                                                                                             12XTALIN
                                                                         55                                                                                                                                                                                             11
                                                                               55PB5/FD5                                                                                                                                                           11XTALOUT




                                                                                                                                                                                                                                                                                                          24Mhz
                                                                         54                                                                                                                                                                                             1
                                                                               54PB4/FD4                                                                                                                                                             1CLKOUT




                                                                                                                                                                                                                                                                                                                  2
                                                                         47                                                                                                                                                                                             9
                                                                               47PB3/FD3                                                                                                                                                               9RDY5
                                                                         46                                                                                                                                                                                             8
                                                                               46PB2/FD2                                                                                                                                                               8RDY4
                                                                         45                                                                                                                                                                                             7




                                                                                                                                                                                                                                                                                                                                12p
                                                                                                                                                                                                                                                                                                                                      C46
                                                                               45PB1/FD1                                                                                                                                                               7RDY3
                                                                         44                                                                                                                                                                                             6
                                                                               44PB0/FD0                                                                                                                                                               6RDY2
                                                                                                                                                                                                                                                                        5
                                                                                                                                                                                                                                                  5RDY1/*SLWD
                                                                         92                                                                                                                                                                                             4
                                                                               92PA7/*FLAGD/SLCS#                                                                                                                                                 4RDY0/*SLRD
                                                                         91
                                                                               91PA6/*PKTEND
                                                                         90                                                                                                                                                                                             98
                                                                               90PA5/FIFOADR1                                                                                                                                                        98CTL5
                                                                         89                                                                                                                                                                                             67
                                                                               89PA4FIFOADR0                                                                                                                                                         67CTL4
                                                                         85                                                                                                                                                                                             66
                                                                               89PA3/*WU2                                                                                                                                                            66CTL3
                                                                         84                                                                                                                                                                                             71
                                                                               84PA2/*SLOE                                                                                                                                                     71CTL2/*FLAGC
                                                                         83                                                                                                                                                                                             70
                                                                               83PA1/INT1#                                                                                                                                                     70CTL1/*FLAGB
                                                                         82                                                                                                                                                                                             69
                                                                               82PA0/INT0#                                                                                                                                                     69CTL0/*FLAGA




                                                                                                                   125GND
                                                                                                                   116GND
                                                                                                                   93GND
                                                                                                                   80GND
                                                                                                                   65GND
                                                                                                                   58GND
                                                                                                                   49GND
                                                                                                                   27GND
                                                                                                                   20GND
                                                                                                                   3GND
                                                                                                                   13AGND
                                                                                                                                                                                  10AVCC
                                                                                                                                                                                  107VCC
                                                                                                                                                                                  100VCC
                                                                                                                                                                                  81VCC
                                                                                                                                                                                  68VCC
                                                                                                                                                                                  64VCC
                                                                                                                                                                                  48VCC
                                                                                                                                                                                  43VCC
                                                                                                                                                                                  26VCC
                                                                                                                                                                                  17VCC
                                                                                                                                                                                  2VCC




                                                                                                                    3
                                                                                                                                                                                                                                    2




                                                                                                                                                                                  81




                                                                                                                   93
                                                                                                                   80
                                                                                                                   65
                                                                                                                   58
                                                                                                                   49
                                                                                                                   27
                                                                                                                   20
                                                                                                                   13
                                                                                                                                                                                  10
                                                                                                                                                                                  68
                                                                                                                                                                                  64
                                                                                                                                                                                  48
                                                                                                                                                                                  43
                                                                                                                                                                                                                                   17




                                                                                                                  125
                                                                                                                  116
                                                                                                                                                                                 107
                                                                                                                                                                                 100




                                  89
                                                                                                                                                                                                                                   C8




                                                                                                                                                                                                                         +3V3 26
                                                                                                                                   GND                                                                                                GND




                                                                                                                                                                           TR6




                                                                                                                                                                                        CLKGND CLKGND
                                                                                                                                                                     R22            R21




                                                                                                                                                                                                                       CLK_GND
                                                                                                                                                                                                                                                   AVDD1.8




                                                                                                                                                                                                             C72




Figure 7.3: Baseband schematic.
                                                                                                                                                                                                               +




                                                                                                                                                                                                  DVDD1.8
                                                                                                                                                                                                                                   CLKGND
                                                                                                                                                                                                                                                        C64


                                                                                                                                                                                  C15                                                                 C69



                                                                                                                                                                                                        L1
                                                              MAX-1                                                                                                 C11                                                                              AGND
                                                                                                                                                                                                                                                   +3V3
                                                 AGND        42
                                                                  XOR              /DORI
                                                                                         41
                                                                                                                                                                                                             C71
                                                                                                                                                                                                               +
                                                             43                          40




                                                                                                            DGND
                                                                  GND                PD
                                                                                                                                                                                                                                                        C70
                                                             44                          39
                                                                  SELIQ            TORB
                                                             45                          38
                                                                  B15              CLKP
                                                             46
                                                                                                                                                                                                             C62 C63



                                                                  B14
                                                             47                                37
                                                                  B13             CLKN
                                                                                                                                                                                                                                                AGND




                                                             48                                35
                                                                  B12            AVCLK
                                                             49                                36
                                                                  B11             GND5
                                                             50                                34
                                                                  B10           AVDD1.8
                                                             51                                33
                                                                  B9              GND6
                                                             52                                32
                                                                  B8           AVDD3.3-3
                                                             53                                31                                                                                                                                                                                                                 4         3
                                                                  B7           AVDD3.3-4
                                                             54                                30
                                                                  B6              GND7
                                                                                                                                                                                                                                                                                                                                                       OUTPUI




                                                             55                                29
                                                                  B5              OUTIP
                                                                                                                                                                                                                                                           R68
                                                                                                                                                                                                                                                                 49.9




                                                             56                                                                                                                                                                                                                                                   5         2
                                                                  B4
                                                                                                                                                                                                                                                                                                                                            AGND




                                                             57         DAC
                                                                  B3
                                                                                                                                                                                                                                                                        R67
                                                                                                                                                                                                                                                                              100ohm
                                                                                                                                                                                                                                                                                         TR8




                                                             58                         28                                                                                                                                                                         AGND
                                                                  B2              OUTIN
                                                                                                                                                                                                                                                                                                        AGND




                                                             59                         27                                                                                                                                                                                                                        6         1
                                                                  B1               GND8
                                                                                                                                                                                                                                                           R23
                                                                                                                                                                                                                                                                 49.9




                                                             60                         26
                                                                  B0               GND9                            AGND                                                                                                                                                                                               TR9
                                                                                        25
                                                                                  DUTQP
                                                                                                                                                                                                                                                                                                                       AGND




                                                             61
                                                                  DVDD




                                       DVDD1.8
                                                 C12 C14                                                                                                                                                                                                                                                          4         3
                                                             62                                24
                                                                  A15             DUTQN
                                                                                                                                                                                                                                                           R50
                                                                                                                                                                                                                                                                 49.9




                                                 1uF 0.1uF   63                                23
                                                                  A14             GND10
                                                                                                                                                                                                                                                                                                                                                       OUTPUTQ




                                                             64                                22                                                                                                                                                                                                                 5         2
                                                                  A13          AVDD3.3-5
                                                                                                                                                                                                                                                                        R55
                                                                                                                                                                                                                                                                              100ohm
                                                                                                                                                                                                                                                                                         TR11




                                                                                                                                                                                                                                                                 AGND
                                                                                                                                                                                                                                                                                                                                            AGND




                                                             65                                21                                                                                                                                              C65
                                                                  A12          AVDD3..3-6
                                                                                                                     AGND




                                                             66                                20                                                                                                                                           +3V3
                                                                  A11              GND11
                                                                                                                                                                                                                                                           R56
                                                                                                                                                                                                                                                                 49.9
                                                                                                                                                                                                                                                                                                        AGND




                                                             67                                19                                                                                                                                                                                                                 6         1
                                                                  A10          AVDD1.8-2
                                                             68                                18                                                                                                                                             C67
                                                                  A9             DACREF                                                                                                                                                                                                                           TR12
                                                  DGND        1                                                                                                      C66
                                                                  A8
                                                                                                                                                                                                                                                                                                                       AGND




                                                              2                                17
                                                                  A7              FSADJ
                                            DGND              3                                16                                                                                                                                              C22
                                                                  A6              REFIO
                                                                                                                                            R66




                                                              4                                15                                                                                                                                             AGND
                                                                                                                                                                                                                                            AVDD1.8
                                                                  A5             GND12
                                                              5                                14
                                                                  A4           AVDD3.3-7
                                                              6                                13                                                                                 C17
                                                                  A3             GND13
                                                              7                                12
                                                                  A2             GND14
                                                              8                                11                   DGND                                                  1uF
                                                                  A1            DVDD3.3
                                                              9                                10                  DGND                                              C23
                                                                  A0             GND15
                                                                                                                                                                       +3V3
                                                                                                        DVDD3.3
                                                                                                                                                                          AGND




                                                              MAX5875-2
                                                                                                                   C19



                                                                                                             DGND
                         Figure 7.4: Baseband Board.


generation of -5V which supplies the differential amplifiers(AD8132). The layout

of the transmitter board is shown on figure 7.7


7.4.3    Receiver

Figure 7.8, Figure 7.9 and Figure 7.10 illustrate the schematics for the receiver

platform. As on the transmitter side, on the receiver the comparator is connected
to the 8 bit address bus. When the received address is equal to the assigned
address the comparator enables the latch (74HCT688). The latch connects the

digital control signals, each corresponding enable inputs on the different chips

on the board. Four different supply sources are utilized for this board: 2.5V,
3.3V, 5V and -5V. Again the power is supplied over the control interface. Linear

voltage regulators are again used for the generation of these supplies. A switch

mode voltage regulator is used for the generation of -5V used on the differential

amplifiers (AD8132). The layout of the receiver board is shown on Figure 7.11.



7.5     Software

As this platform is built for SDR there are significant software elements through

the system. These elements perform several functions, some of them perform

hardware control functions such as changing the desired center frequency or out-
put power levels, while others implement the interface between the PC and the



                                       90
                                                                                                                                                                                                                                                                                                                                                      GND




                                                                                                                                                                                                                                                                                                                                                            3
                                                                                                                                                                                                                                                                                                                                                                                              2
                                                                                                                                                                                                                                                                                                                                                                                                     1
                                                                                                                                                                                                                                                                                                                                                                                                         NC1

                                                                                                                                                                                                                                                                                                                                                                                              NC2

                                                                                                                                                                                                                                                                                                                                                                   GND
                                                                                                                                                                                                                                                                                                                                                                   OUT
                                                                                                                                                                                                                                                                                                                                                                                              NC3
                                                                                                                                                                                                                                                                                                                                                                                                         VCC




                                                                                                                                                                                                                                                                                                                                                            4
                                                                                                                                                                                                                                                                                                                                                                                              5
                                                                                                                                                                                                                                                                                                                                                                                                     6
                                                                                                                                                                                                                                                                                                                                                                               C16




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               C15
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      10uF
                                                                                                                                                                                                                                                                                                                                       51OHM                                   1nF




                                                                                                                                                                                                                                                                                                                                                                                                                              +3.3V_dig
                                                                                                                                                                                 270ohm                                                                                                                                                               R18                      C17
                                                                                                                                    270ohm                                                                                                                                                                                                                                       GND                                                                                  R17




                                                                                                                                                                                                                                                                                                                                 GND
                                                                                                                                                                                           R26                                                                                                                                                                                 1nF




                                                                                                                                                                                                                                                                                                     18
                                                                                                                                                                                                                                                                                                                                17
                                                                                                                                                                                                                                                                                                                                                            16
                                                                                                                                                                                                                                                                                                                                                                                                     15
                                                                                                                                                                                                                                                                                                                                                                                                                                  14
                                                                                                                                                                                                                                                                                                                                                                                                                                                            13
                                                                                                                                       R27                                                                                                                                                                                                                                                                                                                            4.7k




                                                                                                                                                                                                                 R25
                                                                                                                                                                                                                             300ohm
                                                                                                                                                                                                                               GND




                                                                                                                                              R24
                                                                                                                                                    300ohm
                                                                                                                                                                                                                                                                                                                                                                                                                                     CN




                                                                                                                                                                                                                                                                                                                                                                   REF




                                                                                                                                                                                                                                                                                                                                    CLK
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                GND
                                                                                                                                                      GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                              RSET




                                                                                                                                                                                                                                                                                                         DATA
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               C14
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     10nF




                                                                                                                                                                                                                                                                                                                                                                                                         DGND
                                                                                                                                                                                                                                                                                      19                                                                                                                                                                                        12
                                                                                                                                                                                                                                                                                           LE                    Control                                                                                                                                             CC




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND




                                                                                                                                                                                                                                      R23
                                                                                                                                                                                                                                            300ohm
                                                                                                                                                                                                                                                                                                                                                                  14-Bit
                                                                                                                                                                                                                                                                                                                                                                 Counter
                                                                                                                                                                                                                                                                                      20                                                                                                                                                                                        11
                                                                                                                                                                                                                                              GND                                          MUXOUT                                                                                                                                                              AGND4




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND
                                                                                                                                                                                                                                                                                      21                                                                                                                                                                                        10




                                                                                                                                                                                                                                                                                                                                                                                                                 ADF4360-1
                                                                                                                                                                                                                                                                                           DVDD                                                                                                                                                                AGND3




                                                                                                                                                                                                                                                                    +3.3V_dig
                                                                                                                                                                                                                                                                                                                                                                 Multiplexer
                                                                                                                                                                                 270ohm




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND
                                                                                                                                                                                           R28                                                                                        22                                                                                                                                                                                        9
                                                                                                                                                                                                                                                                                           AGND5                                                                                                                                                               AGND2




                                                                                                                                                                                                                                                                                GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND




                                                                                                                                                                                                                                                                                                                                          PreScaler
                                                                                                                                                                                                                                                                                                                                                                                Multiplexer
                                                                                                                                                                  270ohm




                                                                                                                                                                                                                                                                                                                  Lock Detect
                                                                                                                                                                                                                                                                                                                                                                                                                       VCO
                                                                                                                                                                                                                                                                                      23                                                                                                                                                                                        8
                                                                                                                                                                                                                                                                                           CE                                                                                                                                                                      AGND1
                                                                                                                                                                        R29




                                                                                                                                                                                                                                                                                                                                                                 1/2
                                                                                                                                                                                                                                                     R11




                                                                                                                                                                                                  R22
                                                                                                                                                                                                        300ohm
                                                                                                                                                                                                                                                                                                                                                                                                                  Output
                                                                                                                                                                                                                                                                                                                                                                                                                  Stage
                                                                                                                                                                                                                                                                                      24                                                                                                                                                                                        7
                                                                                                                                                                                                                                                                                           CP                                                                                                                                                                    VTUNE




                                                                                                                                                                                                                                                                                                        Pump
                                                                                                                                                                                                                                                                                                Charge
                                                                                                                                                                                                          GND                                        3.9K
                                                                                                                                                                                                                                                                    C12          C11




                                                                                                                                                                                                                                                                                                     CPGND
                                                                                                                                                                                                                                                                                                                                AVDD
                                                                                                                                                                                                                                                                                                                                                            AGND
                                                                                                                                                                                                                                                                                                                                                                                                     RFOUTA
                                                                                                                                                                                                                                                                                                                                                                                                                                  RFOUTB
                                                                                                                                                                                                                                                                                                                                                                                                                                                            VVCO
                                                                                                                                                                                                                                            C13
                                                                                                                                                                                                                                                                    10nF 680pF




                                                                                                                                                                                                                                                                                                1
                                                                                                                                                                                                                                                                                                                                2
                                                                                                                                                                                                                                                                                                                                                          3
                                                                                                                                                                                                                                                                                                                                                                                                     4
                                                                                                                                                                                                                                                                                                                                                                                                                              5
                                                                                                                                                                                                                                                                                                                                                                                                                                                        6
                                                                                                                                                                                                                                            330pF
                                                                                                    +5V_dig
                                                                                                                                                                                                                                                                                                                GND                                                            GND




                                                                                                                                                                                                                                                              R14
                                                                                                                                                                                                                                                                    2k




                                                                                                                                                                               GND
                                                                                                                                                                                                                                                            GND                                                                                                      47nH                                                                           47nH




                                                                                                    5
                                                                                                                                                                                                                                                                                                                                                                                        L4                                                                   L3




91
                                        1                            20




                                                                                                    VDD
                                            E                 VCC                                                                                                                           C25                                                                                                                                                                                                               C9                           C10
                                                                                               74AHC1G04                                                                                                                                                                                                 +3.3V_ang                                                                                                                                          +3.3V_ang
                                       2                             19                    2                                    4       13                                 12
                                            P0 NOT_P=Q                                          A                 Y                           LE                  GND




                                                                                                          GND
                                                                                                                                                                                            2.2nF 10k                                                                                                                                                                                                         1.5pF                        1.5pF




                                 GND
                                       3                             18                                                                 14                                 11




                                                                                 +5V_dig
                                            Q0                  Q7                                                                            PRE                 MR
                                       4                             17                                                                 15                                 10                     R21




                                                                                                          3
                                            P1                  P7                                                                            Q8                   D8
                                       5                             16                                                                 16                                 9




                                                                                                                                                                                                                   +5V_dig
                                            Q1                  Q6                                                                            Q7                   D7
                                       6                             15                                         GND                     17                                 8
                                            P2                  P6                                                                            Q6                   D6




                                                                           GND




                                                  74HCT688
                                       7                             14                                                                 18                                 7                                                                                                                                                                                                                                                                                                                                                                       +5V_ang
                                            Q2                  Q5                                                                            Q5                   D5




                                                                                                                                                                                                                                                                                                                                                                                                    L1
                                                                                                                                                                                                                                                                                                                                                                                                              3.9nH
                                                                                                                                                                                                                                                                                                                                                                                                                             L2
                                                                                                                                                                                                                                                                                                                                                                                                                                           3.9nH
                                       8                             13                                                                 19                                 6
                                            P3                  P5                                                                            Q4                   D4                                                                                                                                                                                                                                                                                                                                                                                                   R13




                                                                           GND
                                                                                                                                                                                             Data Bus




                                                                                                                                                       74ABT843




                                 GND
                                       9                             12                                                                 20                                 5
                                            Q3                  Q4                                                                            Q3                   D3                                                                                                                                                                                                                                                                                                                                                                                                   8K
                                       10                            11                                                                  21                                4                                                                                                                                                                                                                                                                                                                                                                                                  GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   3




                                            GND                 P4                                                                            Q2                   D2                                                                                                                                                                                                                                                                                                                                                 GND                                          C1                C6
                                                                                                                                        22                                 3                                                                                                                                                                                                                                                                                                                                          10pF
                                                                                                                                              Q1                   D1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   3.3pF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       R8            10pF   R6




                                 GND
                                                                                                                                        23                                 2                                                                                                                                                                                                                                                                                                                                                                                   1                                                                    2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   V+




                                                                                                                                              Q0                   D0                                                                                                                                                                                                                                                                                                                                                 C43           R30                 VIN-                                                                              PIN




                                                                                                                                                                                     GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          4                                                                                                     SMA
                                                                                                                                        24                                 1                                                                                                                                                                                                                                                                                                                                                                   VOUT+                    10                  8k
                                                                                                                                              VCC                  OE                                                                                                                                                                                                                                                                                                                                                               50                                                            +5V_ang




                                                                                                                      +5V_dig
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              AD8132 VOCM
                                                             Address Bus                                                                                                                                                                                                                                                                                                  +5V_ang                                                                                                                                                   R31   5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               VOUT-                    R4                  R5




     Figure 7.5: Tx schematic.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               8                                                   2
                                                                                                                                                                                                                                                                                                                                                                                                                                           GND               GND                                                             C42    50                  VIN+                                                           PIN
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   V-




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   C2 10             C5     8k                               SMA
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                1




                                                                                                                                                                                                                                                                                                                                          8
                                                                                                                                                                                                                                                                                                                                                                          7
                                                                                                                                                                                                                                                                                                                                                                                                     6
                                                                                                                                                                                                                                                                                                                                                                                                                             5
                                                                                                                                                                                                                                                                                                                                                                                                                                                   4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             10pF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   6




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             GND                                   3.3pF             10pF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 R1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      280ohm
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        R12


                                                                                                                                                                                                                                                                                                                                                                                                         LOIP
                                                                                                                                                                                                                                                                                                                                                                                                                              LOIN




                                                                                                                                                                                                                                                                                                                                                                               VPS1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      IBBP



                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     IBBN



                                                                                                                                                                                                                                                                                                                                                                                                                                                                      COM1




                                                                                                                                                                                                                                                                                                                                                  ENOP
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        8K
                                                                                                                                                                                                                                                                                                                                                                                                                                                    COM1A
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             1




                                                                                                                                                                                                                                                                                                                                                                                                                  Splitter                                                                                                                        -5V_ang
                                                                                                                                                                                                                                                                                                                                                                                                                  Phase

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               0.1uF


                                                                                                                                                                                                                                                                                                                                                          Bias
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    GND                   GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                C41
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 R2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      25ohm




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             AD8349




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   +5V_ang

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        R16
                                                                                                                                                                                                                                                                                                                                                  COM2
                                                                                                                                                                                                                                                                                                                                                                               COM3
                                                                                                                                                                                                                                                                                                                                                                                                         VOUT
                                                                                                                                                                                                                                                                                                                                                                                                                              VPS2
                                                                                                                                                                                                                                                                                                                                                                                                                                                    COM3A
                                                                                                                                                                                                                                                                                                                                                                                                                                                                      COM3B
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     QBBN
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      QBBP




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        8K    GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   3




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      GND                                          C3         10pF
                                                                                                                                                                                                                                                                                                                                          9




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      10pF
                                                                                                                                                                                                                                                                                                                                                                                                     11



                                                                                                                                                                                                                                                                                                                                                                          10
                                                                                                                                                                                                                                                                                                                                                                                                                             12
                                                                                                                                                                                                                                                                                                                                                                                                                                                   13
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     14
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    15
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     16




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   3.3pFR9     C8           R7                                      2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   V+




                                                                                                                                                                                                                                                                                                                                                         GND                                  GND                                                           GND               GND                                     C45           R32   4             VIN-                                                                              PIN
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               VOUT+                    10                  8K                                                  SMA
                                                                                                                                                                                                                                                                                                                                                                                                              +5V_ang                                                                                                               50
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              AD8132 VOCM
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    R33   5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               VOUT-           8
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        R10                 R3                     2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             C44    50                  VIN+                                                           PIN
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   V-




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   C4 10             C7     8K                               SMA
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             10pF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   6




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             GND                                   3.3pF             10pF
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        R15
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        8K
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  -5V_ang                                                                           GND                   GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               GND


                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            11                            10
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  P4                GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            12                            9
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Q4                 Q3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            13                            8
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  P5                 P3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            14                            7          Address bus
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Q5                 Q2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            15                            6
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  P6                 P2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            16                            5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Q6                 Q1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         74HCT688




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            17                            4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  P7                 P1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            18                            3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Q7                 Q0
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            19                            2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  NOT_P=Q P0
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               GND




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            20                            1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  VCC                 E
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      +5V_dig




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         A




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                VDD
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                +5V_dig




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             74AHC1G04




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   GND
                                                                                                                                                                                                  +5V_dig              +5V_ang
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         Y




                                                                                                                                                                                                              47uH
                                                                                                                                                                      2                       1
                                                                                                                                                                           IN        OUT
                                                                                                                                                                                                               L9                                                                                                                                                             C18                                                                                                                                11                          10
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         4




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      DGND             WR
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  GND




                                                                                                                                                         10uF                                 22uF




                                                                                                                                                                                  GND
                                                                                                                                                                                                                 22uF




                                                                                                                                                                                                                                                                                                               C19
                                                                                                                                                                                LP8345-5                                                                                                                                                                                      100pF                                                                                                                              12                          9                                           11                                  10




                                                                                                                                                                                                                                                                                  GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      PD               CS                                                     LE                GND




                                                                                                                                                                                                                                                                                                      100pF
                                                                                                                                                          C29
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND



                                                                                                                                                                                              C32                    C37




                                                                                                                                                                                 3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 13                          8                                           12                                  9
                                                                                                                                                                                                                                                                       +5V_ang                                                                                                                                             +5V_ang                                                                                    LDAC             DB0                                                    8Q                      8D
                                                                                                                                                                                        GND                                                                                                                                                                                                                                                                                                                      14                          7                                           13                                  8
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      CLR              DB1                                                    7Q                      7D
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND




                                                                                                                                                                                                                                                                                                                                                                                     GND                                                        GND                                                              15                          6                                           14                                  7
                                                                                                                                                                                                  +3.3V_dig            +3.3V_ang                                                                                                                                                                                                                                                                                      VDD              DB2                                                    6Q                      6D
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   +3.3V_dig




                                                                                                                                                                                                                                                                       6
                                                                                                                                                                                                                                                                                          5
                                                                                                                                                                                                                                                                                                                     4
                                                                                                                                                                                                                                                                                                                                                                3
                                                                                                                                                                                                                                                                                                                                                                                            2
                                                                                                                                                                                                                                                                                                                                                                                                                           1
                                                                                                 1               2                                                                                                                                                                                                                                                                                                                                                                                               16                          5                                           15                                  6
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              AD7801




                                                             -5V_ang                                                                                                                                                                                                                                                                                                                                                                                                                                                  REFIN            DB3                                                    5Q                      5D                Data bus
                                                                                                                                                                                                              47uH




                                                                                                                              Power IN
                                                                                                                                                                      2                       1                                                                                                                                                                                                                                                                                                                  17                          4                                           16                                  5
                                                                                                                                                                           IN        OUT                                                                                                                                                                                                                                                                    R20                                                       AGND             DB4                                                    4Q                      4D
                                                                                                                                                                                                                                                                                                                                                                                                                                                                       1k
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    74LVC573




                                                                                                                                                                                                               L10                                                                                                                                                                                                                                                                                               18                          3                                           17                                  4




                                                                                                                                                                                                                                                                                                                                                                     INHI
                                                                                                                                                         10uF                                                                                                                                                                                                                                                                                                                                                         NC               DB5                                                    3Q                      3D




                                                                                                                                                                                                                                                                                                                      INLO
                                                                                                                                                                                                                                                                                                                                                                                                                            VPS1
                                                                                                                                                                                              22uF




                                                                                                                                                                                  GND
                                                                                                                                                                                                                  22uF




                                                                                                                                                                                                                                                                                                                                                                                             COM1
                                                                       47uH                                                                                                                                                                                                                                                                                                                                                                                                 R19
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND




                                                                                                                                                                                                                                                                        VPS1A
                                                                                            1                          8                                                    LP8345-3.3                                                                     7                                                                                                                                                                               24                                                                    19                          2                                           18                                  3




                                                                                                                                                                                                                                                                                              COM1A
                                                                                                OUT              LX                                                                                                                                             VREF                                                                                                                                                                GAIN                                                                              VOUT             DB6                                                    2Q                      2D
                                                                        L14 68uF                                                                          C30                                 C33                    C34




                                                                                                                                                                                 3
                                                                                            2                          7                                                                                                                                                                                                                                                                                                                                                    1.4K                                 20                          1                                           19                                  2




                                                                                                                                                                                                                                               C21
                                                                                                                                                                                                                                                                                        And
                                                                                                FB               V+.                                                                                                                                                                                                                                                                                                                                                                                                  DGND1            DB7                                                    1Q                      1D




                                                                                                                                                                                                                                                                                Vref




                                                                                                                                                                                                                                         1nF
                                                                                                                                                                                                                                                                                               Bias
                                                                                                                                                                                                                                                                                                                                                                                                           Gain
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  GND




                                                                                                                                                                                                                                                                                                                                                             Input
                                                                                                                                                                                                                                                                                                                                                                                                 Control
                                                                                                                           120uF




                                                                                                                                                                                                                                   GND
                                                                                                                                                                                        GND




                                                                                                                                                                                                                                                                                                                                     GM Stage
                                                                              C38           3                          6                                                                                                                                                                                                                                                                                                                                                                                                                                                                 20                                  1




                                                                                                                                                 L12




                                                                                                       MAX764
                                                             22uF                               SHDN             V+                                                                                                                                                                                                                                                                                                                                                                                                                                                                           VCC                    OE
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             +3.3V_dig




                                                                                                                                          47uH
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         GND




                                                                                            4                          5    C39                                                                                                                            8                                                                                                                                                                               23
                                                             C46                                REF             GND                                                                                                    +2.5V_ang                                IPBS                                                                                                                                                                ENBL
                                                                                    0.1uF




                                                                                                                                                                                                                                         1nF
                                                                                                                                                                                                                                               C20
                                                                                                                                                                                                              47uH




                                                                                                                                                                                                                                   GND
                                                                                     C40                                                                              2                       1
                                                                                                                                                                           IN        OUT
                                                                                                                                         GND                                                                   L11                                         9                                                              Continuously                                                                                                     22
                                                                                                                                                         10uF                                 22uF                                                              OPBS                                                                                                                                                            VPS2E




                                                                                                                                                                                  GND
                                                                                                                                                                                                                  22uF
                                                                                                                                                                            LP8345-2.5




                                                                                                                                                                                                                                         1nF
                                                                                                                                                                                                                                                                                                                             Variable




                                                                                                                                                                                                                                               C22
                                                                                                                                                          C31                                 C35
                                                                                                                                                                                                                                                                                                                                                                                                                                                             +5V_ang




                                                                                                                                                                                                                     C36




                                                                                                                                                                                 3
                                                                                                                                                                                                                                   GND
                                                                                                                                                                                                                                                                                                                          Attenuator
                                                                                                                                                                                        GND                                                                10                                                                                                                                                                              21
                                                                                                                                                                                                                                                                COM1C                                                                                                                                                           VPS2D
                                                                                                                                                                                                                                                                                                                                                                                                                                                             +5V_ang




                                                                                                                                                                                                                                                     GND
                                                                                                                                                                                                                                                           11                                                                                                                                                                              20
                                                                                                                                                                                                                                                                COM2                                                                                                                                                            VPS2C
                                                                                                                                                                                                                                                                                                                                                                                                           ADL5330




                                                                                                      +3.3V_ang                                                                   +3.3V_dig
                                                                                                                                                                                                                                                                                                                                                 TZ
                                                                                                                                                                                                                                                                                                                                                                                                                                                             +5V_ang




                                                                                                                                                                                                                                                     GND
                                                                                                                                                                                                                                                                                                                                                                     Output



                                                                                                                                                                                                                                                                                                                             Stage




                                                                                                                                                                                                                                                           12                                                                                                                                                                              19
                                                                                                                                                                                                                                                                COM2A                                                                                                                                                           VPS2B

                                                                                                            CC5              CC6         CC7           CC8      CC9       CC10 CC11
                                                                                                                                                                                                                                                                                                                                                                                                                                                             +5V_ang




                                                                                                                                                                                                                                                     GND
                                                                                                                                                                                                                                                                        VPS2
                                                                                                                                                                                                                                                                                              COM2B
                                                                                                                                                                                                                                                                                                                      OPLO
                                                                                                                                                                                                                                                                                                                                                                     OPHI
                                                                                                                                                                                                                                                                                                                                                                                             COM2C
                                                                                                                                                                                                                                                                                                                                                                                                                            VPS2A




92
                                                                                                            0.1nF            0.1nF 0.1nF 0.1nF 0.1nF 0.1nF 0.1nF
                                                                                                                                                                                                                                                                       13
                                                                                                                                                                                                                                                                                          14
                                                                                                                                                                                                                                                                                                                     15
                                                                                                                                                                                                                                                                                                                                                                16
                                                                                                                                                                                                                                                                                                                                                                                            17
                                                                                                                                                                                                                                                                                                                                                                                                                           18




                                                                                                                GND                                          GND                                                                                                                                      GND                                                                                             GND



                                                                                                                                                                                                                                                                                                 120nH                                                                               120nH

                                                                                                                                                                                                                                                                                                          L5                                                                         L6

                                                                                                      +5V_dig                                    +5V_ang              +2.5V_ang                                                                                 +5V_ang                                                      C23                                              C24                            +5V_ang

                                                                                                                                                                                                                                                                                                                             100pF                                            100pF

                                                                                                                                                                                                                                                                                                                      GND
                                                                                                            CC12             CC2         CC3           CC4                CC1
                                                                                                                                                                                                                                                                                                                          5
                                                                                                                                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                                                                                                                                       3




                                                                                                            0.1nF            0.1nF 0.1nF               0.1nF              0.1nF

                                                                                                                GND          GND                                          GND




                                 Figure 7.6: Tx schematic.




     Figure 7.7: Top Tx Board.
                                                                                                                                                                                                                                                                                                                                                                                      GND




                                                                                                                                                                                                                                                                                                                          1
                                                                                                                                                                                                                                                                                                                                                       2


                                                                                                                                                                                                                                                                                                                       GND
                                                                                                                                                                                                                                                                                                                                                1.2nH
                                                                                                                                                                                                                                                                                                                                                                      L13




                                                                                                                                                                                                                                                                                                                                                                                                           2.2nH
                                                                                                                                                                                                                                                                                                                                                       3
                                                                                                                                                                                                                                                                                                                                                                          2
                                                                                                                                                                                                                                                                                                                                                                                     1




                                                                                                                                                                                                                                                                                                                                                                                                           L7
                                                                                                                                                                                                                                                                                                                                                              IN
                                                                                                                                                                                                                                                                                                                                                                                     VD1
                                                                                                                                                                                                                                                                                                                                                                              GND


                                                                                                                                                                                                                                                                                                                                                 MGA-83563
                                                                                                                                                                                                                                                                                                                                                                                                                                     C26

                                                                                                                                                                                                                                                                                                                                                                                                                           20pF
                                                                                                                                                                                                                                                                                                                                                                                                                     GND




                                                                                                                                                                                                                                                                                                                                                              GND1
                                                                                                                                                                                                                                                                                                                                                                              GND2
                                                                                                                                                                                                                                                                                                                                                                                     OUT
                                                                                                                                                                                                                                                                                                                                                                                                                                                +2.5V_ang




                                                                                                                                                                                                                                                                                                                                                       4
                                                                                                                                                                                                                                                                                                                                                                          5
                                                                                                                                                                                                                                                                                                                                                                                     6




                                                                                                                                                                                                                                                                                                                                                                                                           18nH

                                                                                                                                                                                                                                                                                                                                                                          GND                              L8
                                                                                                                                                                                                                                                                                                                                                                                                           C28
                                                                                                                                                                                                                                                                                                                                                                                                                       50pF




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   PIN
                                                                                                                                                                                                                                                                                                                                                                                           C27                                                                                                           SMA

                                                                                                                                                                                                                                                                                                                                                                                           1pF
                                                                                                                                                                                                                                                                                                                                                                                            GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          GND
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         1




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                GND
                                                                                                                                                                                                                                      synth_clk          1                               2
                                                                                                                                                                                                                                                                 1             2




                                                                                                                                                                                                                                                                 4
                                                                                                                                                                                                                                                                               3




                                                                                                                                                                                                                                                             4
                                                                                                                                                                                                                                                                          3
                                                                                                                                                                                                                                                                                                                                                                                         3
                                                                                                                                                                                                                                                                                                                                                                                                                       2
                                                                                                                                                                                                                                                                                                                                                                                                                                          1
                                                                                                                                                                                                                                      synth_data         1                               2
                                                                                                                                                                                                                                                                 1             2




                                                                                                                                                                                                                                                                 4
                                                                                                                                                                                                                                                                               3
                                                                                                                                                                                                                                                                                                                                                                                                                                              NC1

                                                                                                                                                                                                                                                                                                                                                                                                                          NC2

                                                                                                                                                                                                                                                                                                                                                                                          GND




                                                                                                                                                                                                                                                             4
                                                                                                                                                                                                                                                                          3
                                                                                                                                                                                                                                                                                                                                                                                          OUT
                                                                                                                                                                                                                                                                                                                                                                                                                          NC3
                                                                                                                                                                                                                                                                                                                                                                                                                                              VCC




                                                                                                                                                                                                                                                                                                                                                                                         4
                                                                                                                                                                                                                                                                                                                                                                                                                       5
                                                                                                                                                                                                                                                                                                                                                                                                                                          6
                                                                                                                                                                                                                                      synth_le           1                               2
                                                                                                                                                                                                                                                                 1             2




                                                                                                                                                                                                                                                                 4
                                                                                                                                                                                                                                                                               3




                                                                                                                                                                                                                                                             4
                                                                                                                                                                                                                                                                          3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                C71
                                                                                                                                                                                                                                                                                                                                                                                                                                                                             R39




                                                                                                                                                                                                                                                                                                                                                                    18
                                                                                                                                                                                                                                                                                                                                                                             17
                                                                                                                                                                                                                                                                                                                                                                                         16
                                                                                                                                                                                                                                                                                                                                                                                                                       15
                                                                                                                                                                                                                                                                                                                                                                                                                                          14
                                                                                                                                                                                                                                                                                                                                                                                                                                                         13
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    GND5




                                                                                                                                                                                                                                                                                                                                                                                                                                              CN




                                                                                                                                                                                                                                                                                                                                                                              CLK
                                                                                                                                                                                                                                                                                                                                                                                          REF



                                                                                                                                                                                                                                                                                                                                                                     DATA
                                                                                                                                                                                                                                                                                                                                                                                                                                                          RSET



                                                                                                                                                                                                                                                                                                                                                                                                                          DGND




                                                                                                                                                                                                                                                                                                                                                          control
                                                                                                                                                                                                                                                                                                                                                                                          14-bit_counter
                                                                                                                                                                                                                                                     1                                                  4                      19                                                                                                                                                   12
                                                                                                                                                                                                                                                             1                                4                                         LE                                                                                                                               CC
                                                                                                                                                                                                                                                                                                              C79
                                                                                                                                                                                                                                                                                                                               20                                                                                                                                                   11




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             C75
                                                                                                                                                                                                                                                                                                                                        MUXOUT                                                                                                                AGND4
                                                                                                                                                                                                                                           GND5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               GND5
                                                                                                                                                          1                         5                             1                        2        2                                                   3                      21                                                                                                                                                   10 GND5
                                                                                                                                                                VIN VOUT                                               1         2                           2                                3                                         DVDD                                                                                                                  AGND3




                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                 3
                                                                                                                                                                                                                                                                                                                                                                                                                       ADF4360-1




                                                                                                                           +
                                                                                                                               C74                        3                         4                                                                                                                                          22




                                                                                                                                                                      VSS
                                                                                                                                                                                        +
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    9 GND5
                                                                                                                                                                CE          NC              C73                                                                                                                                         AGND5                                                                                                                 AGND2
                                                                                                                                                                 XC6204




                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                 3
                                                                                                                                                                                                                                                                                                                                                                                                                                                  VCO
                                                                                                                                              C72                                                                                                                                                                         23




                                                                                                                                                                     2
                                                                                                                                                                                                                                                                                                                       GND5             CE                                                                                                                       AGND1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    8 GND5




                                                                                                                                                                                                                                                                                                                                                                                                           prescaler
                                                                                                                                                                                                                                                                                               R41                             24
                                                                                                                                                                                                                      GND5 GND5                                                                                                         CP                                                                                                                    VTUNE
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    7 GND5




                                                                                                                                                                                                                                                                                                                                            Carge
                                                                                                                                                                                                                                                                                                                                            pump
                                                                                                                                                                                                                  1                        2
                                                                                                                                                                                                                       1         2




                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                 3
                                                                                                                                                                                                                                                                                                                                                                     CPGND
                                                                                                                                                                                                                                                                                                                                                                              AVDD
                                                                                                                                                                                                                                                                                                                                                                                          AGND
                                                                                                                                                                                                                                                                                                                                                                                                                          RFOUTA
                                                                                                                                                                                                                                                                                                                                                                                                                                              RFOUTB
                                                                                                                                                                                                                                                                                                                                                                                                                                                          VVCO
                                                                                                                           GND5          GND5                     GND5                                                                                                             C78              C77 C76
                                                                                                                                                                                        GND5




                                                                                                                                                                                                                                                                                                                                                                    1




                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                 3
                                                                                                                                                                                                                                                                                                                                                                             2
                                                                                                                                                                                                                                                                                                                                                                                         3
                                                                                                                                                                                                                                                                                                                                                                                                                       4
                                                                                                                                                                                                                                                                                                                                                                                                                                          5
                                                                                                                                                                                                                                                                                                                                                                                                                                                         6




                                                                                                                                                                                                                                                                                                            R40
                                                                                                                                                                                                                      GND5 GND5
                                                                                                                                                                                                                                                                                                                                                                GND5 GND5


                                                                                                                                                                                                                  1                        2
                                                                                                                                                                                                                       1         2




                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                 3
                                                                                                                                                                                                                                                                                                  INDUCTOR_0402                                                                                                                                                                 INDUCTOR_0402




                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                 3
                                                                                                                                                                                                                                                                                                                          U$19                                                                                                                                                                                     U$18
                                                                                                                                                                                                                      GND5 GND5

                                                                                                                                                                                                                                                                                                                                 C70                                                                                                                                            C69




93
                                                                     1                             5                                      1                                     2
                                                                             VIN VOUT                                                                     1           2




                                                                                                                                                          4
                                                                                                                                                                      3




                                                    +
                                                                                                                       +
                                                        C50         3                              4                       C49




                                                                                  VSS
                                                                             CE         NC




                                                                                                                                                                                                                                                                                                                                     U$17
                                                                                                                                                                                                                                                                                                                                                    INDUCTOR_0402
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      U$16
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             INDUCTOR_0402
                                                                              XC6204




                                                                                                                                                    4
                                                                                                                                                                     3
                                                                C48




                                                                                  2
                                                                                                                                                                                                                                                                                                                                                    1                                                                         AD8347                                                  28
                                                                                                                                                                                                                                                                                                                                                                         LOIN                                                                                            LOIP




                                                                                                                                                                                                                                                                                                  C63
                                                                                                                                                  GND5 GND5
                                                                                                                                                                                                                                                                                                                                                    2                                                                                                                                 27
                                                                                                                                                                                                                                                                                                                                                                         VPS1                                                                                        COM1




                                                                                                                                                                                                                                                                                                  C65
                                                    GND5      GND5             GND5                                    GND5                                                                                                                                                                                                                         3                                                                                                                                 26                      GND5
                                                                                                                                                                                                                                                                                                                                                                         IOPN                                                                                        QOPN
                                                                                                                                                                                                                                           C47                                                                                                      4                                                                                                                                 25
                                                                                                                                                                                                                                                                                                                                                                         IOPP                                                                                        QOPP
                                                                                                                                                                                                                                                                                             GND5                                                   5                                                                                                                                 24
                                                                                                                                                                                                                                                                                                                                                                         VCMO                                                                                            QAIN




                                                                                                                                                                                                                                                                                                                                                                                     +
                                                                                                                                                                                                                                                                                                                                                                                         -
                                                                                                                                                                                                                                                                                                                                                                                                                                                                 -
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     +

                                         GND5                                                                                                                                                                                                                                                                                                       6                                                                                                                                 23
                                                                                                                                                                                                                                                                                                                                                                         IAIN                                                                                    COM3-1

                                                                                                                                                                                                                                                                                                                                                                                                                                   Phase
                                                                                                                                                                                                                                                                                                                                                                                                                                   splitter
                                                6         5     1                            2                                                                                                                                       GND5
                                                                         1              2




                                                                                                                                         R29
                                                4         3                                                                                                                                                                                                                                                                                         7                                                                                                                                 22




                                                                         4
                                                                                        3
                                                                                                                                                                                                                                                                                                                                                                         COM3                                                                                        QMXO                                     GND5        QMXO
                                lna_en          2         1                                                                1                                                                                               C45




     Figure 7.8: Rx schematic
                                                                                                                                  EN2




                                                                                                                                                                                            U$6
                                                                                                                                                                                                  INDUCTOR_0402
                                                                                                                           6                                                                                                                                                                                                                        8                                                                                                                                 21




                                                                                                                                          2
                                                                                                                                                                                                                                                                         IMXO




                                                                        4
                                                                                      3
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    R38




                                                    JP1                                                                           EN1                                                                                                                                                                                     GND5                                           IMXO                                                                                            VPS3
                                                                                                                               MBC13720                                                                                                                                                                                                             9                                                                                                                                 20
                                                                                                                                                                                                                                                                                                                                                                         COM2                                                                                            VDT1




                                                                                                                                                                                                                                     C46
                                                                                                                                                                                                                                                                         C51
                                                                     GND5 GND5
                                                                                                                           4                                                3                                                                                                                                             GND5                 10                                                                                                        DET
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      19
                                                                                                                                  RFIN                        RFOUT                                                                                                                                                                                                      RFIN                                                                                        VAGC
                                                                                                                                                                                                                                                                                                                                               11                                                                                                                                     18




                                                                                                                                               GND BIAS
                                                                                                                                                                                                                                                                                                                                                                         RFIP                                                                                            VDT2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       6         5




                                                                                                                                                                                                                                                                         C52
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      INDUCTOR_0402




                                                                                                                                                                                                                                                   R30
                                                                                                                                                                                                                                                                                                                                               12                                                                                                                                     17                                                                                               4         3           AGC_in




                                                                                                                                          5
                                                                                                                                                                                                                                                                                                                                                                         VPS2                                                                                            VGIN
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       2         1
                                                                                                                                                                                                                                                                                                                           C68

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     U$12




                                                                                             U$4
                                                                                                       INDUCTOR_0402
                                                                                                                                                                                                                                                                                                                                               13                                                                                                                                     16
                                                                                                                                                                                                                                                                                                        R37




                                                                                                                                                                                                                                                                                   C64
                                                                                                                                                                                                                                                                                                                                                                         IOFS                                                                                        QOFS                                                                                                                  JP3                R34
                                                                                                                                                                                                                                                                 GND5                                                                                                                                                  Control
                                                                                                                                                                                                                                                                                                                    GND5                       14                                                                        Gain                           enable
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      15                                         6         5          C54               C53
                                                                                                                                                                                                                                                                                                                                                                         VREF Bias                                                                                   ENBL

                                                                                                                                                                                                                                                                                   C67
                                                                                  C43                                          C44                                                                                                                                                                                 R35                                                                                                                                                                                                           4         3                                                                          C55   C56
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 2         1
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      C66




                                                                                                                                          GND5                                                                                                                                                                                                                                                                                                                                                                                                            GND5              GND5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     R31




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     JP2       GND5
                                                                                                                                                                                                                                                                                                                   R36 C59                                                                                                                                                                              C57 C58
                                                                                                                                                                                                                                                                         GND5                                                                                                                       Vref
                                                                             GND5                                          GND5
                                                                                                                                                                                                                                                                                                                                                                                                                                                                             GND5                                                                                                                     GND5
                                                                                                                                                                                                                                                                                                                                    GND5                                                                                                                                                                      GND5GND5                                1                 2     mod_en
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            1    2
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 3




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 3




                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          GND5 GND5
                                                                                                                                                                                                                                                                                                    1                               5                                                                                       1                                                   2
                                                                                                                                                                                                                                                                                                              VIN VOUT                                                                                                                         1                         2
                                                                                                                                                                                                                                                                                                                                                                                                                                              4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                         3




                                                                                                                                                                                                                                                                     +
                                                                                                                                                                                                                                                                                                                                                                    +




                                                                                                                                                                                                                                                                          C62                     3                                 4                                    C61
                                                                                                                                                                                                                                                                                                                    VSS




                                                                                                                                                                                                                                                                                                              CE          NC
                                                                                                                                                                                                                                                                                                                  XC6204
                                                                                                                                                                                                                                                                                                                                                                                                                                          4
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     3




                                                                                                                                                                                                                                                                                               C60
                                                                                                                                                                                                                                                                                                                   2




                                                                                                                                                                                                                                                                                                                                                                                                                                        GND5 GND5


                                                                                                                                                                                                                                                                     GND5                    GND5                 GND5                                          GND5
                                                                                                                                              R48

                                                                                          GND5
                                                                                                                                           C102




                                                                                                                             6
                                                                                                 C99
                                                                                                                                     8
                                                                                                                                                          R47                         R51
                                                                                                                             VIN+                                                             IMXO




                                                                                                                             V-
                                                                                                                                                                      C103
                                                                                                       R45           5




                                                                                                                                           C112
                                                                                                                      VOUT-
                                                                                                                                     2
                                                                                                       R46       AD8132 VOCM
                                                                                                                  4                                                   C104
                                                                                                                      VOUT+
                                                                                                                                                    GND5 R49                          R52
                                                                                                 C100                                1




                                                                                                                             V+
                                                                                                                             VIN-                                                             Vref
                                                                                                                                           C101




                                                                                                                             3
                                                                                              GND5                                            R50




                                                  1                   5              1                  2    1                   2                         1                           8
                                                      VIN
                                                        VOUT                              1      2               1       2                                      OUT              LX




                                                                                         4
                                                                                                 3
                                                                                                                 4
                                                                                                                         3




                                +
                                                                          +
                                    C115      3                       4       C114                                                                         2                           7




                                                           VSS
                                                      CE         NC                                                                                             FB              V+_
                                                       XC6204                                                                        C96




                                                                                         4
                                                                                                                 4




                                                                                                 3
                                                                                                                         3
                                             C113                                                                                                          3                           6




94
                                                           2
                                                                                                                                                                SHDN             V+

                                                                                                                                                                       MAX764
                                                                                                                                                                                                        C97   C98
                                                                                         GND5 GND5                                                         4                           5
                                                                                                                                                                REF             GND
                                                                                                                                                    C95
                                GND5       GND5         GND5              GND5


                                                                                                                                                                                       GND5
                                                                                                                                              R56




     Figure 7.9: Rx schematic
                                                                                          GND5
                                                                                                                                           C108
                                                                                                                             6
                                                                                                 C105
                                                                                                                                     8
                                                                                                                                                          R55                         R59
                                                                                                                             VIN+                                                                QMXO
                                                                                                                             V-

                                                                                                                                                                      C109
                                                                                                       R53           5
                                                                                                                                           C111




                                                                                                                      VOUT-
                                                                                                                                     2
                                                                                                       R54       AD8132 VOCM
                                                                                                                  4                                                   C110
                                                                                                                      VOUT+
                                                                                                                                                    GND5 R57                          R60
                                                                                                 C106                                1
                                                                                                                             V+




                                                                                                                             VIN-                                                                Vref
                                                                                                                                           C107
                                                                                                                             3




                                                                                              GND5                                            R58
                                                                                                                                                         a7
                                                                                                                                                         a6
                                                                                                                                                         a5
                                                                                                                                                         a4



                                                                                1                     5                                                  vcc
                                                                                    VINVOUT
                                                                                                                                                 GND gnd
                                                                                                                                                       DIGITAL
                                                                                                                                                                                                                                                                                                                                                                      C87




                                                                +
                                                                                                            +
                                                                    C94        3                      4         C93




                                                                                          VSS
                                                                                    CE          NC




                                                                                                                                                                    10
                                                                                                                                                                                    9
                                                                                                                                                                                          8
                                                                                                                                                                                                 7
                                                                                                                                                                                                       6
                                                                                                                                                                                                             5
                                                                                                                                                                                                                    4
                                                                                                                                                                                                                              3
                                                                                                                                                                                                                                    2
                                                                                                                                                                                                                                               1
                                                                                                                                                                                                                                                                                 10
                                                                                                                                                                                                                                                                                         9
                                                                                                                                                                                                                                                                                                    8
                                                                                                                                                                                                                                                                                                             7
                                                                                                                                                                                                                                                                                                                       6
                                                                                                                                                                                                                                                                                                                             5
                                                                                                                                                                                                                                                                                                                                      4
                                                                                                                                                                                                                                                                                                                                            3
                                                                                                                                                                                                                                                                                                                                                   2
                                                                                                                                                                                                                                                                                                                                                              1




                                                                                     XC6204
                                                                              C92




                                                                                         2
                                                                                                                                                                                                                                                E
                                                                                                                                                                                                                                                                                                                                                               E




                                                                                                                                                                                                                                                      C86




                                                                                                                                                                                                                         P1
                                                                                                                                                                                                                                                                                                                                       P1




                                                                                                                                                                                           P3
                                                                                                                                                                                                        P2
                                                                                                                                                                                                                                     P0
                                                                                                                                                                                                                                                                                                       P3
                                                                                                                                                                                                                                                                                                                        P2
                                                                                                                                                                                                                                                                                                                                                    P0




                                                                                                                                                                                                              Q1
                                                                                                                                                                                                                                                                                                                                 Q1




                                                                                                                                                                                     Q3
                                                                                                                                                                                                  Q2
                                                                                                                                                                                                                               Q0
                                                                                                                                                                                                                                                                                           Q3
                                                                                                                                                                                                                                                                                                                  Q2
                                                                                                                                                                                                                                                                                                                                             Q0




                                                              GND       GND         GND                   GND




                                                                                                                                                                     GND
                                                                                                                                                                                                                                                                                   GND
                                                                    DIGITAL   DIGITAL           DIGITAL         DIGITAL
                                                                                                                                                                                                       74HCT688                                                                                                        74HCT688




                                                                                                                                                                     P4
                                                                                                                                                                                     Q4
                                                                                                                                                                                           P5
                                                                                                                                                                                                  Q5
                                                                                                                                                                                                        P6
                                                                                                                                                                                                              Q6
                                                                                                                                                                                                                         P7
                                                                                                                                                                                                                               Q7
                                                                                                                                                                                                                                     NOT_P=Q
                                                                                                                                                                                                                                                VCC
                                                                                                                                                                                                                                                                                   P4
                                                                                                                                                                                                                                                                                           Q4
                                                                                                                                                                                                                                                                                                       P5
                                                                                                                                                                                                                                                                                                                  Q5
                                                                                                                                                                                                                                                                                                                        P6
                                                                                                                                                                                                                                                                                                                                 Q6
                                                                                                                                                                                                                                                                                                                                       P7
                                                                                                                                                                                                                                                                                                                                             Q7
                                                                                                                                                                                                                                                                                                                                                    NOT_P=Q
                                                                                                                                                                                                                                                                                                                                                               VCC




                                                                                                                                                                    11
                                                                                                                                                                                                                                                                                 11




                                                                                                                                                                                    12
                                                                                                                                                                                          13
                                                                                                                                                                                                 14
                                                                                                                                                                                                       15
                                                                                                                                                                                                             16
                                                                                                                                                                                                                    17
                                                                                                                                                                                                                              18
                                                                                                                                                                                                                                    19
                                                                                                                                                                                                                                               20
                                                                                                                                                                                                                                                                                         12
                                                                                                                                                                                                                                                                                                    13
                                                                                                                                                                                                                                                                                                             14
                                                                                                                                                                                                                                                                                                                       15
                                                                                                                                                                                                                                                                                                                             16
                                                                                                                                                                                                                                                                                                                                      17
                                                                                                                                                                                                                                                                                                                                            18
                                                                                                                                                                                                                                                                                                                                                   19
                                                                                                                                                                                                                                                                                                                                                              20




                                                                                                                                                         a3
                                                                                                                                                         a2
                                                                                                                                                         a1
                                                                                                                                                         a0

                                                                                                                                                                                                                                    2
                                                                                                                                                                                                                                                                                                                                                   2




                                                                                                                                                                                                                                     IN
                                                                                                                                                                                                                                                                                                                                                    IN




                                                                                                                          R42




95
                                                                                                                                                                                                GND
                                                                                                                                                                                                        DIGITAL
                                                                                                                                                                                                                                     OUT
                                                                                                                                                                                                                                                                                                                                                    OUT




                                                                                                                                                                                                                   C88
                                                                                                                                                                                                                                    4
                                                                                                                                                                                                                                                                                                                                                   4




                                                                                                                                      GND
                                                                                                                                                 DIGITAL
                                                                                                                                                      1                                           24                                                        GND
                                                                                                                                                                                                                                                                                                            C90




                                                                                                                                                               OE                    VCC                                                                               DIGITAL
                                                                                                                                                                                                                                                                             1                                              20
                                                                                                                                            d7       2                                            23 synth_data                                                                       OE                   VCC
                                                                                                                                                               D0                         Q0
                                                                                                                                                                                                                                                            d0              2                                               19                                        1                           20GND
                                                                                                                                                                                                                                                                                      1D                      1Q                                                            DB7 DGND1                        DIGITAL
                                                                                                                                                                                                                                                                                                                                                                                                                         AGC_in




                                                                                                                                            d6       3                                            22 synth_le
                                                                                                                                                               D1                         Q1
                                                                                                                                                                                                                                                            d1              3                                               18                                        2                           19
                                                                                                                                            d5       4                                            21 synth_clk                                                                        2D                      2Q                                                            DB6        VOUT
                                                                                                                                                               D2                         Q2
                                                                                                                                                                                                                                                                                                                                                                                                               R43




                                  Figure 7.10: Rx schematic
                                                                                                                                                                                                                                                            d2              4                                               17                                        3                           18
                                                                                                                                            d4       5                                            20 mod_en                                                                           3D                      3Q                                                            DB5              NC




     Figure 7.11: Top Rx Board.
                                                                                                                                                                                                                                                                                                                                                                                                                                  R44




                                                                                                                                                               D3                         Q3
                                                                                                                                                                                                                                                            d3              5                                               16                                        4                           17 GND
                                                                                                                                            d3       6                                            19 lna_en                                                                           4D                      4Q                                                            DB4        AGND                    DIGITAL
                                                                                                                                                               D4                         Q4
                                                                                                                                                                                                                                                            d4              6                                               15                                        5                           16
                                                                                                                                            d2       7                                            18                                                                                  5D                      5Q                                                            DB3 REF_IN
                                                                                                                                                               D5                         Q5
                                                                                                                                                                                                                                                                                                74LVC573




                                                                                                                                                                         74ABT843




                                                                                                                                                                                                                                                            d5              7                                               14                                        6                           15
                                                                                                                                            d1       8                                            17                                                                                  6D                      6Q                                                            DB2             VDD
                                                                                                                                                               D6                         Q6
                                                                                                                                                                                                                                                                                                                                                                                  AD7801




                                                                                                                                                                                                                                                            d6              8                                               13                                        7                           14
                                                                                                                                            d0       9                                            16                                                                                  7D                      7Q                                                            DB1             CLR
                                                                                                                                                               D7                         Q7
                                                                                                                                                                                                                                                            d7              9                                               12                                        8                           13
                                                                                                                                                    10                                            15                                                                                  8D                      8Q                                                            DB0            LDAC
                                                                                                                                                               D8                         Q8
                                                                                                                                                                                                                                                                           10                                               11                                        9                           12
                                                                                                                                                    11                                            14                                                                                  GND                     LE                                                            CS               PD
                                                                                                                                                               MR                    PRE
                                                                                                                                                                                                                                                                                                                                                                                                              C91
                                                                                                                                                                                                                                                                 GND                                                                                                 10                           11
                                                                                                                                                    12                                            13                                                                     DIGITAL                                                                                            WR        DGND
                                                                                                                                C89                            GND                        LE
                                                                                                                                                                                                                                                                                                                                                  GND
                                                                                                                                                                                                                                                                                                                                                               DIGITAL
                                                                                                                                                                                                                                                                                                                                                                                                       GND
                                                                                                                                                                                                                                                                                                                                                                                                               DIGITAL
                                                                                                                                  GND
                                                                                                                                             DIGITAL
baseband board and still further elements implement modulation and demodu-

lation by software. Thus the hardware is changed and reconfigured by software
through these elements. There are three different software stacks implemented in
this platform as shown in Figure 7.12 .

 Microcontroller stack:
     This code is run on an 8051 microcontroller embedded in the USB inter-

     face chip on the baseband board. It is written in C and implements the
     embedded control functions such as the frequency synthesizer centre fre-

     quency selection, VGA power control and device enabling and disabling. It

     also manages the baseband board side of the USB interface. The compiler
     used is the SDCC (small device C compiler). The compiled binary file is

     transferred to the microcontroller over the USB interface at USB connection
     time. This allows the updating of the embedded firmware to be updated
     each time the USB connection is made.

 PC driver:

     This code is again written in C and implements a be-spoke USB driver
     as a Linux kernel module. This driver provides separate USB end points

     for configuration control, data input and data output. The configuration
     information is transferred in 64 byte packets to the microcontroller memory

     locations stated earlier, enabling direct control of hardware components

     from the PC. The data is transferred in 512 byte packets, to and from
     FIFOs on the microcontroller side, to and from buffers on the PC side. The

     control and data interfaces are accessed on the PC side through a pseudo-

     file.

 System software:
     This consists of an interface between Matlab and the pseudo-file written in

     C. It is implemented as Matlab mex function. This interface permits the
     implementation of communication schemes directly in Matlab.


                                          96
                                BUFFER
               FIFO
    FIFO                          IN
                IN
                        USB                    PSEUDO        MATLAB
   CONTROL                      BUFFER
                                 OUT           FILE          INTERFACE   MATLAB
              FIFO
              OUT
                                BUFFER
MICROCONTROLLER
                               CONTROL




                           Figure 7.12: Software Stacks.


7.6        Results

Table 7.2 is presenting the resulted specifications for the design of this system.
Results are presented for simple BPSK and QPSK communication schemes using


                              Table 7.2: Specifications
    Receiver                  Transmitter        Baseband
    IIP3: -0.87dBm            Pout : 30dBm       ADC/DAC resolution: 16bits
    Sensitivity: -107dBm      PN: -152dBc/Hz     Sample rate up to 100Msps
    BW: 22MHz                 BW: 22MHz          480Msps USB link
    Frequency range : 1.6GHz to 2.5GHz
    Standards: DCS1800, PCS1900, UMTS-FDD, UMTS-TDD and 802.11b


the SDR platform. These communication schemes are written in the Simulink

Matlab environment. Figure 7.13 shows the receiver implemented in Simulink.

The transmitted signal consists of raised cosine pulse with 50% rolloff at 20kbps

modulated on to a carrier at 2.21GHz using BPSK in the first case and QPSK
in the second case. The receiver implements non data added carrier and timing

recovery. Figure 7.14 shows the constellation for a received BPSK signal after

timing and carrier recovery. Figure 7.15 shows the constellation for a received
QPSK signal again after timing and carrier recovery. Figure 7.16 gives the eye

diagram for the received BPSK signal. Finally Figure 7.17 shows an oscilloscope

capture of the received signal in the BPSK case before digitization.     A photo-
graph of the hardware elements of the platform is shown in Figure 7.18




                                         97
         bpsk1




                                                                                             Discrete−Time
                                                                                              Scatter Plot
                                                                                                Scope1
                                                                                                                                         Discrete−Time
         our_bpsk_r.mat                                                                                                                   Scatter Plot
                                                                                                                                             Scope
           From File

                                Re                                                                                             Sym
                                                                                                                Early−Late Gate
                                Im          5                                Sig                                Timing Recovery
                                                               M−PSK                                                            Ph
                             Real−Imag to   Gain            Phase Recovery
                                                                             Ph
                               Complex                                                                          Early−Late Gate
                                                               M−PSK                                            Timing Recovery
          our_bpsk_i.mat                                    Phase Recovery

             From File1


                                                                                      Re(u)
                                                                                       Im(u)
                                                                                    Complex to
                                                                                    Real−Imag2
                                                                                                                         Discrete−Time
                                                                                                                          Scatter Plot
                                                                                                                            Scope2

                                                     Re(u)
                                                     Im(u)
                                                   Complex to
                                                   Real−Imag                                           Scope1

                                                                                                                        Discrete−Time
                                                                                                                         Eye Diagram
                                                                                                                            Scope




                                                     /home/lruiz/ger/scope_captures/bpsk1.mdl

         printed 28−Nov−2006 00:02                                                                                                       page 1/1




                               Figure 7.13: Matlab implementation.




                                     Point: 530




                Figure 7.14: Constellation for a BPSK received signal.


7.7    Future Work

In this platform USB standard is used for the communication between the PC

and the hardware platform as a first approach. This gives a much faster and


                                                                                   98
         Point: 70




Figure 7.15: Constellation for a QPSK received signal.




Figure 7.16: Eye diagram for a BPSK received signal.




                         99
               Figure 7.17: Received Signal in the Oscilloscope.




                          Figure 7.18: SDR Platform.


cheaper design and implementation of the platform. However, the USB interface
does not have the required bandwidth to support enough data over the USB

bus. Thus a second generation of this SDR platform has already started under
development. This is implemented with FPGA, which gives much faster data

rate in the communication process and the capacity of the bus is increased.



7.8     Conclusion

This thesis has presented a basic hardware test bed for experimentation with SDR

technology. It has been focused on the direct conversion architecture. The adapt-



                                      100
ability of the filter in channel bandwidth, bit rates, IP3 and sensitivity, permits

it to work within the desired group of standards. It is concerned within achiev-
ing many of the air interface specifications which have compatible requirements
providing the capability to operate across a width range of applications.




                                       101
Chapter 8

CONCLUSIONS AND FUTURE
WORK


8.1     Conclusions

This thesis has presented a Software Defined Radio platform to work in a range of
frequencies from 1.6GHz to 2.4GHz. This meets the requirements of 2nd and 3rd

generation mobile telecommunications standards such as: DCS1800, PCS1900,
UMTS-FDD, UMTS-TDD and 802.11b. The implemented platform was built to
allow SDR techniques to be demonstrated.



The SDR communications standards required by this platform were constructed
based on a study of the requirements of the group of standards covered by the

platform Receiver and transmitter specifications were based on the strictest stan-
dard requirements, in this case DCS1800. These are phase noise of -152dBc/Hz,

out-of-band blocker of 0dBm, 30dBm maximum peak output power and 20MHz
of channel bandwidth. However sensitivity levels are limited by the UMTS re-

quirements of -107dBm.



Simulations were carried out in Matlab in order to decide the ADC specifications



                                      102
needed to meet the SFDR requirements of the system. Thus, 16 bits converters,

which can process high dynamic range signals and achieve the requirements of the
standards needed here, were chosen. These ADCs give 8 bits of dynamic range, to
allow for amplitude variation in the incoming signal, according to the simulations.



This SDR platform uses a direct conversion architecture due to its easy tun-

ing across large frequency bands, low power dissipation and low cost. The design

of the platform was divided into three groups: baseband signal processing (ADC,

DAC, USB, LPF), receiver front-end (antenna, RF BPF, demodulator, LNA) and

transmitter (antenna, RF BPF, modulator and PA). This design was constructed
to meet the specifications within the limitations of commercially available com-

ponents.


Filter theory, synthesis and implementation were presented. Low pass filters

were used to ensure suppression of out of channel interference. These were im-
plemented using operational amplifiers in a multiple feedback configuration. RF
bandpass filters were used as band selected filters. These were implemented using
microstrip coupled line configurations. Simulations for both low pass and band-
pass filters were carried out using ADS and Mentor.



Matching networks and simulation results of the amplification stages were de-

tailed. Baseband amplification was used to ensure appropriate signal levels going

into the ADCs. The baseband amplifiers were implemented using operational

amplifiers. RF amplification is used in order to meet the output power require-

ments of the transmitter and the appropriate signal levels into the demodulator.
A power amplifier and a variable gain amplifier were required in the transmitter

in order to keep the SNR of the system within the required specifications. A low
noise amplifier was required by the receiver, which provides enough gain to allow

the mixer to demodulate the required reference signal.



                                       103
Details of the physical implementation of the platform were given. Some of the
problems, such as SNR, found in the implementation process were described. To

improve SNR in the system, sensitive components were shielded from outside
noise.



The software used for this SDR platform was divided in three stacks: micro-

controller, PC driver, system software. An 8051 microcontroller was used, which
is embedded in the USB interface chip. A Linux kernel module was used as the

be-spoke USB driver. Matlab was used as the system software. This interface

permits the implementation of several communication schemes directly in Mat-
lab. The main advantage of this software is the easy communication between PC
and hardware without necessity of a complex application.



Simulation results provided an optimum SNR in the constellations schemes.
Again, Matlab was used to process the data files obtained from the measure-
ments. Receiver and transmitter signal characteristics were measured over the
development of this platform for two particular center frequencies, 2.08GHz and

2.35GHz. These test frequencies were provided by COMREG (the Irish commu-

nication regulator) to the CTVR.



8.2      Comparasion with the Universal Radio Pe-

         ripheral system

Since SDR is a technology highly demanded in the market, several SDR plat-

forms were developed in parallel to this work. One of the most relevant projects

is the Universal Software Radio Peripheral (USRP). This prototype of SDR is
a low cost, high-speed USB based with the high sample-rate processing taking

place in the FPGA. This consists of four high-speed analog-to-digital converters,


                                      104
four high-speed digital-to-analog converters, an FPGA and electronic circuitry

to achieve compatible interface between the different off-the-shelf components.
Two digital upconverters and downconverters are used for the interpolation and
frequency translation of the baseband and RF signals respectively. It is an open

design with freely available driver and schematics. This supports the free GNU
software package to experiment with the SDR daughterboard. The available

daughterboard’s at the moment of this peripheral support different range of fre-

quencies. Transceivers have been done for 1.5GHz to 2.1GHz, and for 2.3GHz to

2.9GHz. However there is no USRP transceiver that is covering 2G,3G and 802.11

communication standards (1.5GHz to 2.4GHz). Table 8.1 gives a comparasion
between the USRP project and the work that has been developed in this master.

As we can see, both project are supporting USB2.0 standard for the data trans-




              Table 8.1: USRP and SDR Platform Comparasion.


mission to the PC. Some of the most important differences of this work with the

USRP project are the number of conversion stages, the architecture used for the
implementation, the sample rate, dynamic range, noise figure and the channel

bandwidth supported for each platform. These parameters and the election of
the direct conversion architecture have been explained in previous chapters.

                                      105
8.3     Future Work

The approach taken in this platform for communication between the PC and the

hardware platform is to use an USB interface. This gives a much cheaper and
faster design and implementation of the platform. However, the USB interface
does not have the required bandwidth to support enough data over the USB bus.

The development of a second generation of this SDR platform is beginning. This
is implemented with FPGA, which gives much faster data rate and an increased

capacity of the bus.


The work presented here may be expanded with the design and implementation

of silicon reconfigurable devices. These must operate in a wide range of frequen-
cies. Future work may also be included in the study of standards to implement

a SDR system with a wider tuning range, which must meet requirements for all
the air-interface standards.




                                      106
Appendix A

ADC Simulations

The simulations of the ADC’s has been carried out using Matlab. Thus in this
appendix the fuction utilized are presented.



A.1      Function ”variance1”

This function is created to generate the plots presented in chapter 4 for the
BER and the converging variance of the signal. The function take as argumen:
the number of samples used for the matlab simulation (samples), the type of
modulation scheme(M) and the number of carriers in the signal(number carriers).

function S N R = variance1(samples,M,number carriers)

%modulation=[2 4 8 16 32 64 256];

 N=samples/256;

 array ruido=[];

 array real=[];



 nBits=log2(M);
 %SNR array=[20 30 45 60 75 80 100];

  for i=1:N
  figure(1)

  real ofdm=simple ofdm1(M,number carriers);

                                      107
real=real ofdm(1:256);

array real=[array real;real];
end

for bits=4:8
%for j=1:7

 SNR=1;

 YY noise=awgn(array real,SNR,’measured’,’db’);
 y = my quantizer(YY noise,bits);

 array ruido=(y-array real);

 figure(2)
 plot(array real)

 figure(3)
 plot(y)
 figure(4)

 plot(array ruido);
 M ruido=sum(array ruido)/length(array ruido);

 M real=sum(array real)/length(array real);
 %e=enerBit(array real,length(array real));

 for k=2:(samples)
 temp ruido=sum((array ruido(1:k)-M ruido).^2);

 %sum(array ruido(1:k).^2)-(sum(array ruido(1:k))).^2;

 v ruido(k-1)=temp ruido/(k-1);

 %temp ruido/(k-1);

 temp real=sum((array real(1:k)-M real).^2);

 %sum(array real(1:k).^2)-(sum(array real(1:k))).^2;
 v real(k-1)=temp real/(k-1);

 %temp real/(k-1);

 %v(k)=(1/k^2)*sum(V(k:i));

 n=1:length(v real);



                                108
figure(5)

plot(n,v real,’bd’,’MarkerEdgeColor’,’k’,
’MarkerFaceColor’,’g’,’MarkerSize’,5)

title(’Converging Variance ofdm’);
hold
figure(6)

plot(n,v ruido,’bd’,’MarkerEdgeColor’,’k’,

’MarkerFaceColor’,’g’,’MarkerSize’,5)

title(’Converging Variance ruido’);

end
Vtruido=(1/(samples)^2)*sum(v ruido);

%Vtotal ruido(bits-3)=Vtruido;
%(1/samples-1)*(sum(array ruido.^2)-(sum(array ruido)).^2);

Vtreal=(1/(samples)^2)*sum(v real);

%Vtotal real(bits-3)=Vtreal;
%(1/samples-1)*(sum(array real.^2)-(sum(array real)).^2);

%10*log10(v real(k)/v ruido(k));
snr=10*log10(Vtreal/Vtruido);
BER T(bits-3)=ber(SNR,snr,M);

S N R(bits-3)=snr;

N bits(bits-3)=bits;

% end

end



figure(7)
semilogy(N bits,BER T(1,:),’+’,N bits,BER T(2,:),’+’,

N bits,BER T(3,:),’-’,N bits,BER T(4,:),’o’,N bits,

BER T(5,:),’*’,N bits,BER T(6,:),’:’,N bits,BER T(7,:),’--’);

grid



                                109
legend(’BPSK’,’QPSK’,’8QAM’,’16QAM’,’32QAM’,’64QAM’,’256QAM’,7);

title(’ADC resolution’);
xlabel(’n bits’);

ylabel(’BERT’);


figure(8)

semilogy(S N R,BER T(1,:),S N R,BER T(2,:),S N R,BER T(3,:),S N R,

BER T(4,:),S N R,BER T(5,:),S N R,BER T(6,:),S N R,BER T(7,:));

grid

title(’ADC resolution’);
xlabel(’snr’);

ylabel(’BER’);


figure(9);

semilogy(N bits,BER T);
grid
legend(’4’,’5’,’6’,’7’,’8’,5);
title(’Ber’);

xlabel(’Nbits’);

ylabel(’BER’);


figure(10);

semilogy(SNR,BER T);

legend(’4’,’5’,’6’,’7’,’8’,5);

xlabel(’SNR’);
ylabel(’BER’);

grid
title(’Ber’);




                              110
A.2       Function ”simple ofdm1”

Function used to generate an OFDM signal. In the function the cycle prefix of

the signal is removed. The function takes as arguments: modulation scheme (M)
and number of carriers.

function [Pyy,real ofdm sig]= simple ofdm1(M,num sym)
%%%%%%%%%%%%
%OFDM generation script for Ger

%defines the sub-carrier modulation scheme - choose whichever one you

%want!

%method=’modulation type’
switch M
case 2
fid = fopen(’OFDMsignal BPSK’,’wb’);

case 4

fid = fopen(’OFDMsignal QPSK.pcm’,’wb’);

case 8

fid = fopen(’OFDMsignal 8QAM.pcm’,’wb’);
case 16
fid = fopen(’OFDMsignal 16QAM.pcm’,’wb’);

case 32

fid = fopen(’OFDMsignal 32QAM.pcm’,’wb’);

case 64

fid = fopen(’OFDMsignal 64QAM.pcm’,’wb’);
case 256

fid = fopen(’OFDMsignal 256QAM.pcm’,’wb’);

otherwise

disp(’wrong modulation’);
end

% QPSK: M= 4

                                    111
% 8-QAM: M=8

% 16-QAM: M= 16
% 32-QAM : M=32
% 64-QAM: M=64

% 256-QAM: M=256
ofdm tx = [];

dyn sig prefix = [];
g prefix = [];

dyn ofdm = [];

%change this if you like but keep num sym <= fftSize/2 -1
%num sym = 1;

fftSize = 256;
numCarr = num sym;
carrSpacing = 1;

fft array = zeros(fftSize,1);
null signal length1 = int16(fftSize/6);

% Converting null signal lengh1 to double elements because It’s not
% possible to use zero() with an element type int16
null signal length=double(null signal length1);

null signal = zeros(abs(null signal length),1);

MidFreq = fftSize/4;%find the middle of the spectrum

CarrSpacing = 1;

StartCarr = MidFreq - round(((numCarr-1)*CarrSpacing/2));

FinCarr = MidFreq + floor(((numCarr-1)*CarrSpacing/2));

carriers = [StartCarr:CarrSpacing:FinCarr]+1;
negCarriers = fftSize-carriers+2;

%find the bins for the negative frequency carriers
for k=1:500

qam= randint(num sym,M,1);



                                112
f=1000*(0:511)/1024;

msg=qaskenco(qam,M);
fft array(carriers(1,1:numCarr),1) = msg(1:numCarr,1);

fft array(negCarriers(1,1:numCarr),1) =
conj(fft array(carriers(1,1:numCarr),1));
ofdm sig = ifft(fft array,fftSize);

%just to make sure the signal is real-valued

real ofdm sig = real(ofdm sig)*32767.0;
real ofdm sig = [real ofdm sig; null signal];

s=size(null signal);
Y = fft(real ofdm sig,1024);

Pyy = Y.* conj(Y)/1024; %Power spectrum
k=size(Pyy);
plot(f,(Pyy(1:512)));

l=size(f);
xlabel(’f’);
title(’OFDM Power Spectrum’);
count = fwrite(fid,real ofdm sig,’int16’);

end
status = fclose(fid);

display(’OFDM creation done...’);



A.3      Function ”my quantizer”

This function simulates an uniform quantizer to generate the digital signal. The

input arguments that the function have are: the information signal(x), the reso-
lution(N bits).

function y = my quantizer(x,n bits)

% --------------- [y,digital]=my quantizer(x,N bits) --------------


                                      113
%

% Conversor A/D with uniform quantization of N bits
%          Full scale, FE:+-1 voltio

%          delta=2*FE/(2^N bits)
%
% Input:

%      x: sampled Analog Signal to codec (volt),

%      N bits: number of bits of the quantizer

% ------------------------------------------------------------

FE=max(abs(x));
delta=2*FE/(2^n bits);% step size

l=length(x)
% UNIFORM QUANTIZER
% The absolut value of all input arguments of the signal must be < 1

x1=x+delta/2;
dec=round(x1/delta);% number of step.It is between 1 and 2exp(n bits)

y=(dec*delta)-delta/2;%value of the quantized signal:
xq=(1/2)*(2*dec - 1)*delta
noise quant= x-y;

% ENCODING

for row=1:l

% 1) first bit, sign: - => 0 / + => 1

if sign(y(row))==1

digital(row,1)=1;

else
digital(row,1)=0;

end
% 2) Siguientes n-1 bits, magnitud cuantificada

aux=0;



                                   114
for col=2:n bits

% Al escal?n m?s alto le asignaremos el c?digo 1000...0
if (abs(dec(row))/2^((n bits-1)-aux-1))==2

% the value of x is lying in the middle of the scale,
%it’s meaning that

% the quantized value is zero, thus the digital

%numaber will be both 00000..0 or 100..0

for col=2:n bits
digital(row,col)=0;

end
else

% If the cocient is less than 1 this position will be 0
% if not the value will be 1
if (abs(dec(row))/2^((n bits-1)-aux-1))<1

digital(row,col)=0;
else
digital(row,col)=1;
% En caso de ser pos. restamos

%la potencia si es neg. la % sumamos

if sign(y(row))==-1
dec(row)=dec(row)+2^((n bits-1)-aux-1);

else

dec(row)=dec(row)-2^((n bits-1)-aux-1);

end

end
aux=aux+1;

end
end

end



                                 115
SNR dB=(6.02*n bits)-7.26; %paper equation of Review of quantization



A.4       Function”ber”

This function generates the BER corresponding to each particular mudulation

scheme. The input arguments are: SNR and modulation scheme.

function[BER] = ber(SNR1,SNR2,M)

%    SNR1 is the signal to noise ratio inside throgh the channel
%    The relationship between Q and erfc is given by:

%      Q(x) = 0.5*erfc(x/sqrt(2));

snr1=10.^(SNR2/10);%Convert Eb/No from dB to a linear ratio
switch M
case {2,4}%BPSK
    BER= .5*erfc(sqrt(snr1));

case {16,64,256}%{8QAM,16QAM,32QAM,64QAM,256QAM}
    BER=2*(1-(1/sqrt(M)))*erfc(sqrt((3/(2*(M-1)))*(snr1)));
case{8,32}

BER=2*(1-(1/sqrt(2*M)))*erfc(sqrt((3/(2*(M-1)))*(snr1)));

end
% Note: Q(x) = 0.5*erfc(x/sqrt(2))




                                     116
Appendix B

Transmitter and Receiver Drivers


B.1       Transmitter Inicialization

A mask is assigned to each variable. The memory address in the microprocessor
for this instruccions is assigned as well.

xdata at 0x40C3      unsigned char OURRX PLL = 0x10;

sfr at 0x8E ckcon;
volatile xdata at 0xe600 unsigned char cpucs;

volatile xdata at 0xe601 unsigned char ifconfig;


data unsigned char sclk mask = 0x40;

data unsigned char sdat mask = 0x01;

data unsigned char sclk mask inv=0xBF ;
data unsigned char LE mask = 0x02 ;

data unsigned char LE mask inv = 0xFD ;

data unsigned char ourclock buf = 0x10;

data unsigned char Demod mask = 0x08;

data unsigned char Demod mask inv = 0xF7;
data unsigned char CE mask = 0x04;

data unsigned char CE mask inv = 0xFD;


                                         117
B.2       Receiver Inicialization

A mask is assigned to each variable. The memory address in the microprocessor

for this instruccions is assigned as well.

xdata at 0x400F unsigned char OURRX PLL = 0x10;

sfr at 0x8E ckcon;
volatile xdata at 0xe600 unsigned char cpucs;

volatile xdata at 0xe601 unsigned char ifconfig;


data unsigned char sclk mask = 0x40;

data unsigned char sdat mask = 0x01;

data unsigned char sclk mask inv=0xBF ;
data unsigned char LE mask = 0x02 ;
data unsigned char LE mask inv = 0xFD ;

data unsigned char ourclock buf = 0x10;

data unsigned char Demod mask = 0x08;
data unsigned char Demod mask inv = 0xF7;

data unsigned char CE mask = 0x04;

data unsigned char CE mask inv = 0xFD;



B.3       Common Functions

B.3.1      Main Function

In the main function all the variables are configured with the corresponding val-
ues. Thus ’conf clk’ is the function which realize this process.

void main (void)

{
unsigned char i = 0;

cpucs = 0x12;      // 0x02 = 12MHz , 0x0a = 24MHz , 0x12 = 48MHz

                                         118
ifconfig &= 0x7f;     // set the ifclk pin for input

ckcon &= 0xF8;    // set the strech values to the most agressive
enable CE();

config clk();
while(1)
{

for (i=0; i<=1; i++)

{

waiting();// waste some clock cycles

}
//config clk();

}
}


B.3.2      Function ”config clk()”

This function has the task to configurate the PLL.

void config clk (void)
{
unsigned char ourdata1 = 0x00;

unsigned char ourdata2 = 0x00;

unsigned char ourdata3 = 0x00;
unsigned char i = 0;

unsigned char j = 0;

//Write in the R counter R=80

rdata1 = 0x00;
ourdata2 = 0x01;

ourdata3 = 0x41;
data write(ourdata1,ourdata2,ourdata3);

toggle LE();

                                     119
for (i=0; i<=128; i++)

{
// waste some clock cycles
}

//For 2.35GHz with 250KHz compare frequency. The loop band width is 25KHz.
//writing on the Control latch

ourdata1 = 0x40;

ourdata2 = 0x01;

ourdata3 = 0x00;

data write(ourdata1,ourdata2,ourdata3);
toggle LE();

waiting();
for (i=0; i<=128; i++)
{

// waste some clock cycles
}
//Writing on the N counter with B=587 and A=8
ourdata1 = 0x02;

ourdata2 = 0x4B;

ourdata3 = 0x22;
data write(ourdata1,ourdata2,ourdata3);

toggle LE();

for (i=0; i<=128; i++)

{

}
}


B.3.3     Function ”data write”

With the following function is possible to write any kind of data in the variables.


                                       120
unsigned char data write(unsigned char ourdata1, unsigned char ourdata2,

unsigned char ourdata3)
{
unsigned char i = 0;

unsigned char sdat = 0x0;



for (i=0; i<=7; i++)

{

sdat = ((ourdata1 >> 7-i) & 0x1);

f (sdat==0x0)
{

ourclock buf &= 0xFE;
}
if (sdat==0x1)

{
ourclock buf |= 0x01;

}
toggle sclk();

}
for (i=0; i<=7; i++)

    {

sdat = ((ourdata2 >> 7-i) & 0x1);

if (sdat==0x0)

{

ourclock buf &= 0xFE;
}

if (sdat==0x1)
{

ourclock buf |= 0x01;



                                121
}

toggle sclk();
}

for (i=0; i<=7; i++)
{

sdat = ((ourdata3 >> 7-i) & 0x1);

if (sdat==0x0)

{
ourclock buf &= 0xFE;

}
if (sdat==0x1)

{
ourclock buf |= 0x01;
}

toggle sclk();
}
ourclock buf &= 0xFE;

OURRX PLL = ourclock buf;

//ourclock buf &= sclk mask inv;     //set sclk=0
//OURRX PLL = ourclock buf;

return 0;

}


B.3.4    Function ”enable CE”

Function which enables the modulator and demodulator.

unsigned char enable CE(void)

{
unsigned char i = 0;

ourclock buf |= CE mask;    //sets CE=1

                                   122
ourclock buf |= Demod mask;     //sets CE=1

OURRX PLL = ourclock buf;
return 0;

}


B.3.5     Function ”toggle LE”

Function which generate a square signal for the LE input on the LE interface
digital line in the PLL.

unsigned char toggle LE(void)

{

unsigned char i = 0;
ourclock buf &= LE mask inv;     //set sclk=0
OURRX PLL = ourclock buf;

for (i=0; i<=1; i++)

{
// waste some clock cycles
}
ourclock buf |= LE mask;    //sets sclk=1
OURRX PLL = ourclock buf;

for (i=0; i<=2; i++)

{

// waste some clock cycles

}

ourclock buf &= LE mask inv;     //set sclk=0

OURRX PLL = ourclock buf;

for (i=0; i<=1; i++)

{
// waste some clock cycles

}

                                    123
return 0;


B.3.6    Function ”Toggle sclk”

Function which generate the clock output from the USB interface chip.

unsigned char toggle sclk(void)

{unsigned char i = 0;
ourclock buf &= sclk mask inv;      //set sclk=0
OURRX PLL = ourclock buf;

for (i=0; i<=1; i++)

{

// waste some clock cycles}
ourclock buf |= sclk mask;     //sets sclk=1
OURRX PLL = ourclock buf;

for (i=0; i<=2; i++)

{
// waste some clock cycles
}
ourclock buf &= sclk mask inv;      //set sclk=0
OURRX PLL = ourclock buf;

for (i=0; i<=1; i++)

{

// waste some clock cycles

}

return 0;

}




                                     124
Appendix C

Microstrip Lines Theory

Transmission lines can support three different kind of wave modes:


TEM: This mode does not have longitudinal field components. They have a

defined voltage, characteristic impedance and current.
TM: Transmission mode characterized by transverse magnetic waves and longi-

tudinal electric fields.
TE: Transmission mode characterized by transverse electric waves and longitu-

dinal magnetic fields.



In the case of TM and TE modes, a unique characteristic impedance is not
possible to define. However some approximations can be done so characteristic

impedance can be used. Thus, here a general introduction to Maxwell’s equations
for each case in a electromagnetic wave is presented. The electric and magnetic

fields of a a wave propagated along the z-axis are:



                      E(x, y, z) = [e(x, y) + z   ez (x, y)]e−jβz        (C.1)

                     H(x, y, z) = [h(x, y) + z    hz (x, y)]e−jβz        (C.2)

Where e(x, y) and h(x, y) represent the transverse (x,y)electric and magnetic
filed. Therefore assuming the transmission in a free region these equations can

                                        125
be written as:


                                  × E = −jωµH                              (C.3)

                                     × H = −jω E                           (C.4)

From the above vector equations each transversal component for magentic and
electric field can be obtained [26]. Since the equations for the transversal com-
ponents in a wave have been obtained is possible to obtain the characteristic

impedance and transversal fields for each propagated mode. Presented below are

the equations for these calculations:

  1. TEM
                                              Ex   ωµ
                                  ZT EM =        =                         (C.5)
                                              Hy   β
                                              1
                              h( x, y) =           z × e(x, y)             (C.6)
                                           ZT EM

  2. TE
                                     Ex   −Ey   ωµ   kn
                            ZT E =      =     =    =                       (C.7)
                                     Hy   Hx    β    β
                                        √    2π
                                     k=ω µ =                               (C.8)
                                              λ

  3. TE
                                     Ex   −Ey   β   βη
                            ZT M =      =     =   =                        (C.9)
                                     Hy   Hx    ω   k
                                        √    2π
                                     k=ω µ =                              (C.10)
                                              λ

Where k is the wave number of the material filling the transmission line or waveg-

uide region [26]. Therefore both TE are TM waves are frequency dependent.



Considering the previous equations and knowing that microstrip lines are are

composed by a hybrid TM-TE wave it is possible to analyses microstrip lines.
Thus quasi-TEM modes are considered when the dielectric substrate is electri-


                                        126
cally very thin (d < λ). In this case the fields are the same as those of static case.

Thus Microstrip line will have an unique characteristic impedance for a partic-
ular frequency. However the impedance in microstrip line is highly depending
on the substrate and the conductor charateristics. In consequence the following

equations are used for the calculation of the microstrip line parameters [26].


                                               r   +1         r   −1              1
                                     e   =            +                                                        (C.11)
                                                   2              2              1+   12H
                                                                                       W



Where 1 <     e   <    r   and is the effective dielectric constant. It is considered as

having a medium to replace the air and dielectric regions.

The characteristic impedance of the line can be calculated as:


                                         60            8H   W                           W
                            Z0 =              ln(         +    )                 f or     ≤1                   (C.12)
                                          r            W    4H                          H
                                    120π                                                        W
         Z0 =      W
                                                                                         f or     ≥1           (C.13)
                  rH      + 1.393 + 0.667 ln( W + 1.444)
                                              H
                                                                                                H
                                 W
Knowing Z0 and        r    the   H
                                         can be calculated as follows:


                                     W    8eA                                    W
                                       = 2A                               f or     <2                          (C.14)
                                     H  e −2                                     H
 W  2                      r −1                    0.61                                                       W
   = (B − 1 − ln(2B − 1) +      ln(B − 1) + 0.39 −      )                                              f or      >2
 H  π                       2r                       r                                                        H
                                                                                                                (C.15)

where
                                     Z0            r   +1         r −1         0.11
                           A=                             +            (0.23 +      )                          (C.16)
                                     60                2          r +1           r

                                                             377π
                                                       B=      √                                               (C.17)
                                                            2Z0 r

The propagation constant and pahse velocity can be expresed as:

                                                               c
                                                         νp = √                                                (C.18)
                                                                      e


                                                                      √
                                                        β = K0             e                                   (C.19)


                                                            127
Figure C.1is a synthesis graph to obtain the corresponding width and height of

the microstrip line.




                                 Figure C.1




                                 Figure C.2




                                     128
Appendix D

Filters


D.1      Lumped Components Filters Response

Maximum flat filters, Bessel filters, and Gaussian filters response with lumped
components habe been analyzed for this platform.

  1. Bessel Response

     Bessel filters are characterized for having a flat group delay and no over-
     shoot. Figure D.1 and Figure D.2 show the implementation and response

     of this bandpass filter.   The simulated filter is a 4th order pi filter with




                       Figure D.1: Bessel schematic.


     bandwidth from 1.8GHz to 2.6GHz. Observing the figures this filter has

     a very small attenuation across the stop band which results a not reliable
     model for this platform, as it said previously. In addition, the values for

     the serial capacitors are very difficult to achieve with lumped components.

  2. Maximum Flat Response

     This kind of filter has very good in band amplitude flattened. The simu-

                                      129
              Figure D.2: Bessel Filter Response.


lated filter is a 5th order pi filter with bandwidth from 1.8GHz to 2.6GHz.

Figure D.3 and Figure D.4 shown the implementation and response of this

bandpass filter. Thus, according to the components values, the series ca-
pacitors are not able to be built since their values are in the order of fF.




               Figure D.3: Max Flat schematic.


According to the frequency response, the maximum flat presents better at-
tenuation characteristics in the stop band than the Bessel filter. However

in relation to the requirements of this platform the filter does not meet the
specifications since the 20dB attenuation occurs at 3GHz, which is over the

required stop frequency for the expected filter.




                Figure D.4: Max Flat Response.



                                  130
3. Gaussian

  The simulated LC bandpass Chebyshev filter is a 3rd order filter with a band
  width from 1.8GHz to 2.6GHz. The filter presents a not flat response which
  can generate attenuation problems on the required signal at the desired

  frequencies. However according to the attenuation at the stop band the
  filter presents very good attenuation characteristics and small number of

  components. Figure ?? and Figure ?? illustrate the implementation and

  response of this LC bandpass filter. Thus, according to the values on the

  filter, series capacitors and parallel inductors are difficult to find in the

  market.




                 Figure D.5: Gaussian LC Filter.




                 Figure D.6: Gaussian Response.




                                  131
Appendix E

Papers

 1. ”A Platform for the Development of Software Defined Radio” IEEE PIMRC
   2007 Greece.

 2. ”Demonstration of a Software Defined Radio Platform for dynamic spec-
   trum allocation” IEEE DYSPAN 2007 Dublin.

 3. ”Reconfigurable Transceiver Architectures: Front-end Hardware Require-

   ments” RIA Colloquium on Physical Layer Wireless Communications,
   Dublin 2006.

 4. ”Reconfigurable Radio Testbed” ISSC 2006, Dublin.




                                  132
   ACRONYMS


ADC, Analog to Digital Conversion
AGC, Automatic Gain Control

AMPS, Advanced Mobile Phone Service
ASIC, Application Specific Integrated Circuit

BER, Bit Error Rate

BPSK, Binary Phase Shift Key

CDMA, Code Division Multiple Access

CMOS, Complementary Metal-Oxide Semiconductor
CPU, Central Processing Units

CSD, Circuit Switch Data
DAC, Digital to Analog Conversion
DCS, Digital Cellular System

DECT, Digital Enhanced Cordless Communications
DSA, Dynamic Spectrum Allocation
DSRC, Dedicated Short Range Communications
EMI, Electromagnetic Interferences

ETC, Enhanced Throughput Cellular

FCC, Federal Communication Commission
FPGA, Field Programmable Gate-Array

GMSK, Gaussian Minimum Shift Keying

GSM, Global System for Mobile Communications

HSDPA, High-Speed Downlink Packet Access

HSUPA, High-Speed Uplink Packet Acess
iDEN, Integrated Digital Enhaced Network

IF, Intermediate Frequency
IFFT, Inverse Fast Fourier Transform

ISI, Intersymbol Interferences



                                     133
ITS, Intelligent Transportation System

ITU, International Telecommunication Union
LAN, Local Area Network
LNA, Low Noise Amplifier

LO, Local Oscillator
NMT, Nordic Mobile Telephone

NF, Noise Figure

OFDM, Orthogonal Frequency Division Multiplexing

OS, Operating System

PA, Power Amplifier
PAN, Personal Area Network

PC, Personal Computer
PCS, Personal Communication System
PN, Phase Noise

PLL, Pahse Locked Loop
PSK, Phase Shift Key
QAM, Quadrature Amplitude Modulation
RF, Radio Frequency

SDR, Software Defined Radio

SFDR, Spurious Free Dynamic Range
SMA, Surface Mount Assembly

SMD, Surface Mount Device

SMT, Surface Mount Technology

SNR, Signal to Noise Ratio

TACS, Total Access Communication System
UMTS, Universal Mobile Telecommunication System

USB, Universal Serial Bus
WiMax, Worldwide Interoperability for Microwave Access

WiBro, Wireless Broadband



                                    134
W-CDMA, Wideband Code Division Multiple Access

WWRF, Wireless World Research Forum




                                135
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                                     138

								
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