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High-Sensitivity-Radio-Receiver-Design by drr53761

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									High Sensitivity Radio
   Receiver Design
        Webinar




           1
                    National Semiconductor Confidential
Panelists
•  Bobby Matinpour
  –  Marketing Manager, Wireless Infrastructure Solutions


•  Scott Kulchycki
  –  Marketing Manager, High Speed Signal Path




                               2
                                                   National Semiconductor Confidential
Objectives
•  Discuss Base Station Market Trends & Needs
•  Review Radio Receiver Basics
•  Describe Receiver Architectures & Trade-Offs
•  Describe the High-IF Receiver Requirements
  –  RF & IF blocks, anti-aliasing filter, and the ADC
•  Demonstrate an Example Using National’s Portfolio
  –  ADC16DV160, LMH6517, and LMK04000
•  Call to Action




                                 3
                                                         National Semiconductor Confidential
Base Station Market Trends & Needs
•  Network Efficiency
  –  More user channels in a given radio


•  Lower Total Cost of Ownership
  –  Infrastructure hardware, deployment and operation




                               4
                                                   National Semiconductor Confidential
Base Station Market Trends & Needs
•  Flexible & High Capacity Base Stations
  –  Multi-Carrier
     •  Enable higher capacity per radio


  –  Multi-Standard
     •  Flexible deployment along with legacy infrastructure
     •  Streamlined development & maintenance


  –  Wideband
     •  Enable higher capacity per radio
     •  Flexible deployment along with legacy infrastructure
     •  Streamlined development & maintenance



                                     5
                                                               National Semiconductor Confidential
Radio Receiver Basics




          6
                  National Semiconductor Confidential
Radio Receiver Overview
•  Function
  –  Translate RF signal to lower frequency digital bits


•  Wireless Markets & Applications
  –  Cellular Base Stations & Repeaters
  –  Point-to-Point RF & Microwave Links
  –  Microwave Backhaul




                                7
                                                      National Semiconductor Confidential
Radio Receiver Figure of Merit
•  Receiver Sensitivity
  –  Normal (non-Blocking) Condition
     •  How small of a signal can the receiver detect and process
     •  Most critical receiver performance metric is Noise Figure
  –  Blocking Condition
     •  How small of a signal can the receiver detect and process in the
        presence of a strong interferer (source closer to antenna)
     •  Most critical receiver performance metric is Linearity




         Strong                                                   Signal
        Interferer

                                     8
                                                                 National Semiconductor Confidential
Receiver Architectures
•  Homodyne (Direct Conversion)
  –  Directly converting RF to baseband quadrature signals
     •  Simple but difficult to get high performance


•  Heterodyne
  –  Converting RF to low-frequency IF using single or multiple
     down-conversion stages
     •  Complex but yields the best performance




                                      9
                                                       National Semiconductor Confidential
Homodyne (Direct Conversion) Receiver
                                        Quadrature          Anti-Aliasing
                                          Mixer      DVGA       Filter          ADC
            Antenna
             Filter   LNA   RF Filter



                                                                   I-channel
                                                            LO

                                              90°


•  Advantages
  –  All IF filtering in baseband
  –  No image rejection filters                                  Q-channel
•  Disadvantages
  –  Needs stringent I & Q channel phase & amplitude balance
  –  LO is in-band and can radiate through antenna
  –  DC offsets and 2nd order intermodulation are now in-band

                                         10
                                                                        National Semiconductor Confidential
Heterodyne Receiver
  Antenna                                                           Anti-Aliasing
   Filter   LNA   RF Filter   Mixer        IF Filter Chain   DVGA       Filter              ADC




                                      LO




•  Advantages
  –  Multiple stages of filtering allows for high performance
  –  DC offsets and 2nd order intermodulation are now out of band
•  Disadvantages
  –  Requires multiple filtering stages (more complex)
  –  Frequency planning is much more complex



                                               11
                                                                                    National Semiconductor Confidential
Filtering in Heterodyne Receivers
•  RF Filtering
  –  Image band
  –  Mixer two-two spurs (2xLO ± 2xRF)
  –  Out-of-band blockers & interferers




                                                           High-IF Example
                                                           in-band
                                            image          blocker signal            interferer




                                                           LO       RF
                                          mixer 2-2 spur
                                     12
                                                                      National Semiconductor Confidential
Filtering in Heterodyne Receivers
•  RF Filtering
  –  Image band
  –  Mixer two-two spurs (2xLO ± 2xRF)
  –  Out-of-band blockers & interferers
•  IF Filtering (no more filtering on 2-2 spur & image)
  –  Remaining out-of-band blockers & interferers
  –  Harmonics of the in-band blocker
  –  Wide-band noise                                            High-IF Example
                  in-band blocker                               in-band
       signal                                    image          blocker signal            interferer
                    2nd harmonic of
                    In-band blocker




                             interferer

        IF                                                      LO       RF
                                               mixer 2-2 spur
                                          13
                                                                           National Semiconductor Confidential
Filtering in Heterodyne Receivers
•  RF Filtering
  –  Image band
  –  Out-of-band blockers & interferers
  –  Mixer two-two spurs (2xLO ± 2xRF)
•  IF Filtering (no more filtering on 2-2 spur & image)
  –  Remaining out-of-band blockers & interferers
  –  Harmonics of the in-band blocker
  –  Wide-band noise                                        Low-IF Example
                                                        in-band
                                                image   blocker signal            interferer




                                                            LO   RF
                                           mixer 2-2 spur
                                      14
                                                                   National Semiconductor Confidential
Filtering in Heterodyne Receivers
•  RF Filtering
  –  Image band
  –  Out-of-band blockers & interferers
  –  Mixer two-two spurs (2xLO ± 2xRF)
•  IF Filtering (no more filtering on 2-2 spur & image)
  –  Remaining out-of-band blockers & interferers
  –  Harmonics of the in-band blocker
  –  Wide-band noise                                          Low-IF Example
              in-band blocker                                in-band
     signal                                       image      blocker signal            interferer
              2nd harmonic of
              In-band blocker




                          interferer

      IF                                                       LO     RF
                                            mixer 2-2 spur
                                       15
                                                                        National Semiconductor Confidential
Frequency Planning for a High-IF Receiver
•  Filtering
  –  RF filtering simplifies with higher IF
     •  Image & Mixer 2-2 spurs are further away from the desired signal
  –  IF filtering simplifies with higher sample rate & IF
     •  Lower-order filter required


•  Amps & Converters
  –  Data converters perform better at lower IF & sample rates
     •  Better SNR & SFDR
  –  Amplifiers perform better at lower IF frequency
     •  Lower Noise & Better Linearity




                                      16
                                                             National Semiconductor Confidential
IF Filtering – Selecting a Sampling Rate


                                                     Desired signal



                                                     Signal will alias
                                                     in-band on sampling
     fS/2       fS    3fS/2        2fS

     Increase                 Decreased slope
     Sampling Rate
                               Relaxed filter requirements




               fS/2                fS            3fS/2
                              17
                                                     National Semiconductor Confidential
IF Filtering – Selecting an IF


                                                            Desired signal


                                                            In-band blocker

                         fS   3fS/2          2fS            Signal will alias
   Amplifier HD2 Distortion
                                                            in-band on sampling
                              Decreased slope
        Increase IF            Relaxed filter requirements




         fS/2            fS                  2fS                             3fS
                                 Amplifier HD2 Distortion
                                 18
                                                            National Semiconductor Confidential
Multi-Carrier Multi-Standard
 20-MHz Receiver Example




             19
                        National Semiconductor Confidential
Multi-Carrier Receiver Design Example
•  Requirements (including Multi-Carrier GSM)
  –  Sensitivity in 200-kHz bandwidth
     •  -104 dBm under normal condition (no margin)
     •  -92 dBm under blocking condition
        –  -16 dBm in-band & out-of band blockers
     •  Require 9-dB Carrier-to-Noise-and-Interference Ratio


•  Frequency Plan
  –  ADC Sample Rate = 76.8 or 153.6 Msps
  –  IF centered at middle of Nyquist zone
     •  Chose 3rd Nyquist zone (192-MHz) to simplify anti-aliasing filter




                                     20
                                                                National Semiconductor Confidential
Multi-Carrier Receiver Design Example
•  Noise & Gain Calculations
  –  Under Normal Condition
    •  Noise
       –  Thermal Noise Floor = -174 dBm + 10 x log(200e+3) = -121 dBm
       –  Maximum Noise Figure = -121 dBm + 9 dB - 104 dBm = 8 dB
    •  Gain
       –  No limitation; need to make sure to not saturate any stages
  –  Under Blocking Condition
    •  Noise
       –  Not a critical spec since limitation is the blocker
    •  Gain
       –  Maximum gain is set by blocker & ADC full-scale (~4-dBm)
          »  Rx Gain = 0 dBm (4-dB back-off from FS) – (-16 dBm) = 16 dB


                                    21
                                                                National Semiconductor Confidential
Multi-Carrier Receiver Design Example
   Antenna                                                           Anti-Aliasing
    Filter   LNA   RF Filter   Mixer        IF Filter Chain   DVGA       Filter              ADC




                                       LO



-16 dBm      Blocker                    Gain = 16 dB                                  0 dBm
-92 dBm                                 NF = ? dB
                          Signal                                                     -76 dBm




                                                22
                                                                                     National Semiconductor Confidential
   Design Example: RF Front-End
        Antenna                                                                       Anti-Aliasing
         Filter     LNA       RF Filter        Mixer         IF Filter Chain   DVGA       Filter            ADC




                                                        LO

    G    -1 dB     16 dB       -1 dB          -7.5 dB
   NF     1 dB     0.8 dB       1 dB           7.5 dB
OP1dB             14 dBm                       8 dBm




                            Cascaded Noise Factor:

                                                                23
                                                                                                  National Semiconductor Confidential
   Design Example: Blocking Condition
        Antenna                                                                         Anti-Aliasing
         Filter     LNA       RF Filter        Mixer         IF Filter Chain    DVGA        Filter            ADC




                                                        LO

    G    -1 dB     16 dB       -1 dB          -7.5 dB                0 dB        ? dB       -5 dB
   NF     1 dB     0.8 dB       1 dB           7.5 dB                9 dB        ? dB        5 dB                ?
OP1dB             14 dBm                       8 dBm                            ? dBm




                                                                                 DVGA Gain Range
                                                                           Blocking Condition = 16 - 1.5 = 14.5
    G    20 dB    -20 dB       20 dB          -20 dB
   NF    5.5 dB    20 dB       5.5 dB          20 dB                    Normal Condition = -1.5 + DVGA max gain
OP1dB   20 dBm                20 dBm


                            Cascaded Noise Factor:

                                                                24
                                                                                                    National Semiconductor Confidential
   Design Example: Blocking Condition
         Antenna                                                                         Anti-Aliasing
          Filter    LNA     RF Filter    Mixer          IF Filter Chain        DVGA          Filter            ADC




                                                   LO

    G     -1 dB  16 dB       -1 dB       -7.5 dB                0 dB           14.5 dB       -5 dB
   NF      1 dB  0.8 dB       1 dB        7.5 dB                9 dB            12 dB         5 dB                ?
OP1dB           14 dBm                    8 dBm                                15 dBm
  Out   -17 dBm -1 dBm      -2 dBm      -9.5 dBm           -9.5 dBm            5 dBm        0 dBm

                                                                                                         4-dB back-off
                                                                                                         from fullscale


                                                                               Tracing the Blocker
                                                                          Stay 10-dB below P1dB at all times
    G     20 dB   -20 dB      20 dB   -20 dB
   NF     5.5 dB   20 dB      5.5 dB   20 dB
OP1dB    20 dBm              20 dBm
  Out   10.5 dBm -9.5 dBm   10.5 dBm -9.5 dBm



                                                           25
                                                                                                     National Semiconductor Confidential
Design Example: Normal Condition
     Antenna                                                                       Anti-Aliasing
      Filter     LNA     RF Filter         Mixer        IF Filter Chain   DVGA         Filter            ADC




                                                   LO

 G    -1 dB    16 dB       -1 dB         -7.5 dB                0 dB      22 dB        -5 dB
NF     1 dB    0.8 dB       1 dB          7.5 dB                9 dB      5.5 dB        5 dB                ?

                                                                                      Max Gain




                        Cascaded Noise Factor:

                                                           26
                                                                                               National Semiconductor Confidential
Design Example: Normal Condition
     Antenna                                                                      Anti-Aliasing
      Filter       LNA    RF Filter    Mixer         IF Filter Chain     DVGA         Filter            ADC




                                                                              1   7                                  6        0
                                                                       LM H65                              1   6 DV1
                                                LO
                                                                                                  ADC
 G    -1 dB      16 dB    -1 dB       -7.5 dB                0 dB        22 dB        -4 dB
NF     1 dB      0.8 dB    1 dB        7.5 dB                9 dB        5.5 dB        4 dB                ?


                               Gain overall = 23.5 dB
                          NF overall < 8 dB  ADC NF = 27.5
              ADC Noise Density = -174 dBm/Hz + 27.5 dB - 3.5-dB margin = -150 dBm/Hz
                     -150 + 79 = -71 dBm/76.8MHz (156.3 Msps)
                                  SNR = 75-dB FS



                                                        27
                                                                                              National Semiconductor Confidential
Design Summary
•  Review of the Numbers
  –  Sensitivity
     •  Meet -104 dBm under normal condition (with 3.5-dB margin)
        –  Simulation confirms -107.2 dBm
     •  Meet -92 dBm under blocking condition (with 4-dB margin)
        –  Simulation confirms -95.5 dBm


•  National’s High-IF Receive Sub-System
  –  LMH6517, ADC16DV160, and LMK04000




                                   28
                                                            National Semiconductor Confidential
High IF Receiver Sub-System
•  Solution using LMH6517+ADC16DV160+LMK04000
 –  Accelerate design of multi-carrier multi-standard receivers




                              29
                                                    National Semiconductor Confidential
Call to Action
•  Go to National’s website for more information
  –  ADC16DV160: http://www.national.com/pf/DC/ADC16DV160.html
  –  LMH6517: http://www.national.com/mpf/LM/LMH6517.html
  –  LMK04000: http://www.national.com/pf/LM/LMK04000.html


•  Check on High-IF Sub-System Board (Late Sept)

•  View other webinars such as Clock & Timing Webinar on
   PowerWise Design University

•  Download & examine Wireless Communications Brochure:
   http://www.national.com/vcm/NSC_Content/Files/en_US/
   Documents/national_comms_infrastructure.pdf


                                 30
                                                        National Semiconductor Confidential
Contact Information
•  Bobby Matinpour
  –  Marketing Manager, Wireless Infrastructure Solutions
  –  Email: Babak.Matinpour@nsc.com
  –  Desk: (408) 721- 7235
  –  Mobile: (408) 332 - 4321


•  Scott Kulchycki
  –  Marketing Manager, High Speed Signal Path
  –  Email: Scott.Kulchycki@nsc.com
  –  Desk: (408) 721- 5851
  –  Mobile: (408) 832 - 9391



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                                                   National Semiconductor Confidential
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     National Semiconductor Confidential

								
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