Important Characteristics of Digital Oscilloscopes and RADAR Pulse

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Important Characteristics of Digital Oscilloscopes and RADAR Pulse Powered By Docstoc
					  and Southeastern Michigan                                   present…




Important Characteristics of
      Digital Oscilloscopes

                                                              Vince Woerdeman,
                   and                                        Agilent Technologies




RADAR Pulse Measurements
  with Digital Oscilloscopes                                  Marty Gubow,
                                                              Agilent Technologies



              5:30 – 6:00 Pizza and Refreshments
              6:00 – 7:00 Technical Presentation
              This is a FREE event.    Non-Members Welcome!                     1
Agenda
Click to edit Master subtitle style
 Evaluating a Scope’s Performance
  Characteristics
     What Bandwidth is needed?
     What Sample Rate is needed?
     How does Nyquist’s Theorem and
     aliasing apply to oscilloscopes?
     Acquisition Errors and Interleave
     Distortion
     What are other important
     characteristics?
                           Page 2
Evaluating Performance Characteristics
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   Is Full Scope Functionality Retained?
  Required Number of Channels?
  Required Bandwidth/Acquisition Performance?
  Waveform Update Rate, Decode Update Rate, Probing,
  Ease-of-use, Display Quality, Triggering, etc.?




                           Page 3
“Rule-of-thumb” Bandwidth Suggestion
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                                                   Scope Bandwidth




 Suggested Bandwidth = 5X Highest Clock Rate

   Allows capture of the 5th harmonic with minimum attenuation.




                                Page 4
Accurate Bandwidth Determination
 Step to Determine fastest rise/fall times
Click #1: edit Master subtitle style of device-under-test.
 Step #2: Determine highest signal frequency content (fKnee).
                fKnee = 0.5/RT (10% - 90%)
                fKnee = 0.4/RT (20% - 80%)
 Step #3: Determine degree of required measurement accuracy.

                Required          Gaussian             Maximally-flat
                Accuracy          Response              Response
                  20%           BW = 1.0 X fKnee      BW = 1.0 X fKnee
                   10%          BW = 1.3 X fKnee      BW = 1.2 X fKnee
                    3%          BW = 1.9 X fKnee      BW = 1.4 X fKnee


 Step #4: Calculate required bandwidth.

   Source: Dr. Howard W. Johnson, “High-speed Digital Design – A Handbook of Black Magic”

                                           Page 5
System Bandwidth Calculation
Example
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Determine the minimum required bandwidth of an
oscilloscope with an approximate Gaussian frequency
response to measure a 500ps rise-time (10-90%):

                  fKnee = (0.5/500ps) = 1GHz


                                     1.4          1.4GHz
      3% Accuracy: Scope Bandwidth = 1.9 x 1GHz = 1.9GHz
     20% Accuracy: Scope Bandwidth = 1.0 x 1GHz = 1.0GHz




                              Page 6
Analog Bandwidth Comparisons
Click to edit Master MHz clock
What does a 100 subtitle style
signal really look like?


                                                                         Rise Time = 495ps




                                                     Rise Time = 550ps
                                                                         2GHz
                                                                         Scope
                                                     1GHz
                                 Rise Time = 750ps
                                                     Scope
                                 500MHz
             Rise Time = 2.5ns
                                 Scope

       100MHz Scope                 Page 7
How Much Sample Rate is Required?
Engineer Fred has total trust style
Click to edit Master subtitlein Dr. Nyquist and says:
         “2X over the scope’s
             bandwidth.”

        Engineer Betty doesn’t trust Dr. Nyquist and says:

                          “10X to 20X over the
                          scope’s bandwidth.”


     The truth lies somewhere in between!
                            Page 8
Nyquist’s Sampling Theorem
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                         Nyquist’s sampling theorem states that for a
                         limited bandwidth (band-limited) signal with
                         maximum frequency fmax, the equally spaced
                         sampling frequency fs must be greater than twice
                         of the maximum frequency fmax, i.e.,
                                              fs > 2·fmax
                         in order to have the signal be uniquely
                         reconstructed without aliasing.


                         The frequency 2·fmax is called the Nyquist
                         sampling rate (fS). Half of this value, fmax, is
                         sometimes called the Nyquist frequency (fN).



    Dr. Harry Nyquist

                             Page 9
Nyquist’s Basic Rules…
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      But not-so-simple for DSO technology

 1. fMAX < fS/2
       The highest frequency sampled MUST be less than fS/2…

       This is NOT the same as oscilloscope bandwidth.



 2. Samples MUST be equally spaced
       The forgotten rule!



                             Page 10
Ideal Brick-wall Response w/ BW @ Nyquist (fN)
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            0dB

         -3dB
  Attenuation




                                     fN   fS
                      Frequency
                           Page 11
Gaussian Response w/ BW @ fS/2 (fN)
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           0dB

         -3dB
 Attenuation




                 Aliased Frequency Components




                                                     fN   fS

                                     Frequency
                                           Page 12
500MHz scope sampling @ 1GSa/s (BW = fS/2 = fN)
                                      S      N

Click to edit Master subtitle style




                           Page 13
Gaussian Response w/ w/ @ S/2 (fN)
Maximally-Flat ResponseBWBW f@ fS/2.5 (fN/1.25)
                              /4 /2)
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            0dB

          -3dB
  Attenuation




                  Aliased Frequency Components

                  Aliased Frequency Components

                              fS/4        fS/2.5      fN   fS

                                      Frequency
                                            Page 14
500-MHz scope (2 GSa/s vs. 4 GSa/s)
         Input = 100 MHz clock with 1 ns
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    2 GSa/s (fBW = fS/4 = fN/2)



                                            4 GSa/s (fBW = fS/8 = fN/4)




                                  Page 15
6-GHz scope (20 GSa/s vs. 40 GSa/s)
          edit 1.25 GHz clock with 100 ps
Click toInput =Master subtitle style edge speeds
     20 GSa/s (fBW = fS/3.3)



                                         40 GSa/s (fBW = fS/6.6)




                               Page 16
Complying with Nyquist’s Rule #1 (fS > 2 x fMAX)
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   2X sampling violates Rule #1

   2.5X to 5X sampling sufficiently satisfies Rule #1

   > 5X sampling provides further compliance with Rule
  #1… IF additional error sources are not introduced
  that violate Rule #2



           Engineers often overlook Rule #2…
           “Samples MUST be evenly spaced”

                            Page 17
Real-time Non-interleaved ADC System
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 Input                     ADC #1     ACQ
                                            To CPU
                                      MEM

            Analog
           Amplifier
                                            Sample
                                             Clock




                           Page 18
Sample Rate > 4 x fBW (Non-interleaved)
                            Sin(x)/x
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                         Input Signal
                    Interpolated Waveform




Sample
Clock


          = Input Signal
          = Sample Clock
          = Sin(x)/x Interpolated Waveform
          = Real-time Digitized Point
                                    Page 19
Real-time Interleaved ADC System
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 Input                            ADC #1          ACQ
                                                            To CPU
                                                  MEM

            Analog
           Amplifier
                                                            Sample
 Input                                            ½ Clock    Clock
                                                   Delay



                                  ADC #2          ACQ       To CPU
                                                  MEM


           Accurate ADC interleaving requires:
           1.   Matched vertical response of each ADC
           2.   Precise phased-delayed clocking
                                 Page 20
SR > 8 x fBW (Perfectly Interleaved)
                             Sin(x)/x
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                     Interpolated Waveform
                          Input Signal




Clock #1

Clock #2

           = Input Signal
           = Sample Clock
           = Sin(x)/x Interpolated Waveform
           = Real-time Digitized Point
                                     Page 21
SR > 8 x fBW (Poorly Interleaved)
                            Sin(x)/x
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                     Interpolated Waveform
                         Input Signal




Clock #1

Clock #2

           = Input Signal
           = Sample Clock
           = Sin(x)/x Interpolated Waveform
           = Real-time Digitized Point
                                     Page 22
Testing for Interleave Distortion
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     Interleave distortion violates Nyquist’s Rule #2:
           “Samples must be evenly spaced”


 1. Effective bits analysis using sine waves

 2. Visual sine wave test

 3. Spectrum analysis

 4. Measurement stability/repeatability


                            Page 23
1-GHz Sine Wave on 1-GHz BW Scopes
4 GSa/s (non-interleaved)
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                                                             20 GSa/s (interleaved)




                                                           Interleave Distortion




           4 GSa/s produces superior results compared to 20 GSa/s


                                       Page 24
2.5-GHz Sine Wave on a 3-GHz Scope
20 GSa/s (Single-chip ADC)
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                                                 40 GSa/s (Dual-interleaved ADC chip-set)




                  Vp-p (σ) = 2.4
                  mV

                                                       Vp-p (σ) = 1.8 mV

        Precision ADC interleaving technology produces improved measurements


                                      Page 25
2.5-GHz Sine Wave on a 2.5-GHz Scope
10 GSa/s (Single-chip ADC)
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                                                 40 GSa/s (Quad-interleaved ADC chip-set)


                                Interleave Sampling Distortion




              Vp-p (σ) = 9.1
              mV
                                                    Vp-p (σ) = 12.0 mV

           Poor ADC interleaving technology produces degraded measurements


                                      Page 26
FFT Analysis of 2.5-GHz Sine Wave at 40 GSa/s
3-GHz to edit
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                                                       2.5-GHz Scope




                       10-GSa/s Distortion (-32 dB)
                                                      40-GSa/s Distortion




                          Page 27
400-MHz Clock Sampled @ 40 GSa/s
       to edit Master subtitle style
ClickScope
 3-GHz


                                                          2.5-GHz Scope




    Rise Time (avg.) = 250ps
    Rise Time (range) = 35ps
    Rise Time (σ) = 3.3ps




                               Rise Time (avg.) = 254ps
                               Rise Time (range) = 60ps
                               Rise Time (σ) = 10ps




                                Page 28
FFT Analysis of 400-MHz Clock at 40 GSa/s

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3-GHz Scope

                                                      2.5-GHz Scope




                           10-GSa/s Distortion
                       (27 dB below 5th harmonic)   40-GSa/s Distortion




                             Page 29
Other Oscilloscope Characteristics to Consider

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   Waveform Update Rate
   Advance Analysis
   Display Quality
   Ease-of-use
   Probing
   Price




                           Page 30
InfiniiMax Active Probe Extension
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     Allows for environmental chamber testing up 105 degrees C.

                              Page 31
Questions and Answers
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                           Page 32
Oscilloscope
   Radar
Measurement
  Basics

               33
Agenda
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     • Introduction
         • Pulsed Power and Power Spectrum
             Measurements
         • Noise Measurements
         • Component Measurements
         • Evaluating I/Q Demodulator Errors
         • Pulsed Component Measurements
         • Time Domain Measurements
         • Jitter Measurements
 Radar Measurement Basics
                              Page 34
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                            Introduction




                                Page 35
 Radar Measurement Basics
Some Typical Radar Applications
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   • Surveillance             • Proximity fuses
    • Search and track          • Altimeter
    • Fire control              • Terrain avoidance
    • Navigation                • Weather mapping
    • Missile guidance          • Space




                            Page 36
 Radar Measurement Basics
The Wide Range of Measurement
Requirements
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              Parameter                Typical Range
      • Frequency………………………………..100MHz - 95GHz
      • Pulse Width (PW)……………………….10nsec to Infinite
          (CW)
      • Pulse Repetition Frequency …………30Hz to 300KHz
      • Rise Time………………………………...1nsec - 100nsec
      • Duty Cycle……………………………….0.01% - 100%
      • Peak Power………………………….…..1W - 50MW
      • Pulse Compression…………………….FM, Phase Coded
      • Frequency Agility……………………….100MHz - 2GHz (BW)
                            Page 37
 Radar Measurement Basics
Simplified Pulse Doppler Radar
Block Diagram
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                                                                                                      PULSED                   Antenna
                                                                                    RF     PREDRIVER POWER    DUPLEXER
                                         COHO              BPF    AMP               BPF      AMP    TRANSMITTER




                                                        STALO                    PRF              PULSE            RECEIVER
                                                                              GENERATOR         MODULATOR         PROTECTION

                                     Transmitter/Exciter

                                                                                                                          LNA

                                                VIDEO
                                                                                          FREQUENCY
                             ADC   S/H    LPF    AMP                                       AGILE L.O.


                                                                   o
                                                                 0
 DI
    SP          Doppler            COHO LIMITER LPF              SPLITTER
         LA
           Y     and
                Range
                 FFT                                       o            2nd    IF                    1st
                                                         90                                                  IF
               Processor                                                IFA   BPF                    IFA    BPF

                                                                                              2nd
                                                                                              L.O.
                             ADC   S/H   LPF    VIDEO
                                                 AMP
                                                                                     Receiver/Signal Processor



                                                           Page 38
  Radar Measurement Basics
Active Electronically Steered
Antenna
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                                     t
                               e Fron
                            Wav




                                    Transceiver
 Animation

                                         Page 39
 Radar Measurement Basics
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                           Page 40
Click to edit Master subtitle style




                           Page 41
Agenda
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         • Introduction
         • Pulsed Power and Power Spectrum
             Measurements
         • Noise Measurements
         • Component Measurements
         • Evaluating I/Q Demodulator Errors
         • Pulsed Component Measurements
         • Jitter Measurements
         • Time Domain Measurements

                                  Page 42
 Radar Measurement Basics
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    Pulsed Power and Power Spectrum
             Measurements




                            Page 43
 Radar Measurement Basics
Why Measure Power?
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 • High peak power influences the expense of the
   system
                  $             $
                                Modulator,             Output
                                PFN, etc.              Stage


 • Power determines the absolute
    range
                            4
                                Pt
                     ∝
                                                           R
               R


                                             Page 44
 Radar Measurement Basics
Instruments Used to Measure
Power
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                • Power
                    Meter




                                      • Vector Signal
                                       Analyzer
   • Spectrum
       Analyzer
 Radar Measurement Basics
                            Page 45
Agenda
Click to edit Master subtitle style
         • Introduction
         • Pulsed Power and Power Spectrum
             Measurements
         • Noise Measurements
         • Component Measurements
         • Evaluating I/Q Demodulator Errors
         • Pulsed Component Measurements
         • Time Domain Measurements
         • Jitter Measurements

                                  Page 46
 Radar Measurement Basics
Noise Figure
Click to edit Master subtitle style ratio as the signal passes
   -the degradation in the signal-to-noise
                                 through the network




                     S                                       S
                     N                  G
                            in                               N   out




                                   (S/N)in
             Noise Figure, F =
                                   (S/N)out
                                                 T = 290°K

                                       Page 47
 Radar Measurement Basics
N8975A Noise Figure Analyzer
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                               • Wide frequency range
                                 (1.5GHz/3GHz/26.5GHz)
                               • Graphical data display
                               • Ease of use
                               • Variable IF bandwidths
                               • Intuitive user interface
                               • Smart Noise Source (cal
                                 files stored in EEPROM
                                 and internal temperature
                                 sensor)

                            Page 48
 Radar Measurement Basics
Agenda
Click to edit Master subtitle style
         • Introduction
         • Pulsed Power and Power Spectrum
             Measurements
         • Noise Measurements
         • Component Measurements
         • Evaluating I/Q Demodulator Errors
         • Pulsed Component Measurements
         • Jitter Measurements
         • Time Domain Measurements

                                  Page 49
 Radar Measurement Basics
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                            Component Test




                                  Page 50
 Radar Measurement Basics
Why make Network Analyzer
measurements on a Radar
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 • Verify specifications of “building blocks” for more
   complex RF systems
 • Ensure distortionless transmission of
       communications signals
    • Linear: constant amplitude/linear phase /
      constant group delay
    • Non-linear: harmonics, intermodulation,
      compression, AM-to-PM conversion
 • Ensure a good match when absorbing
       power (e.g. an antenna)

                            Page 51
 Radar Measurement Basics
The Need for Both Magnitude and
Phase
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                         S21
      1. Complete
         characterization of            S11                    S22
         linear networks
                                                S12
      2. Complex impedance                                           4. Time-domain
         needed to design                                               characterization
         matching circuits
                                                                        Mag


      3. Complex values                                                            Time
         needed for device
         modeling    High-frequency transistor model                 5. Vector-error correction
                                                                                   Error
                 Base
                                                       Collector
                                                                        Measured
                                                Emitter
                                                                                      Actual

                                                    Page 52
 Radar Measurement Basics
 PNA Performance Network Analyzer
 Family
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                             • Up to 35 μs/point
                               measurement speed
                             • 143 dB dynamic range
                                   with direct receiver
                                   access
                               • 128 dB dynamic range at
                                   test ports
                               • 0.005 dB trace noise (10
                                   kHz IF bandwidth
                               • 3, 6, 9, 20, 40, and 50
                                   GHz microwave models
                               • 4 mixer-based receivers
                                   enable TRL/LRM
                           Page 53 calibration
Radar Measurement Basics
Agenda
Click to edit Master subtitle style
     • Introduction
         • Pulsed Power and Power Spectrum
             Measurements
         • Noise Measurements
         • Component Measurements
         • Evaluating I/Q Demodulator Errors
         • Pulsed Component Measurements
         • Jitter Measurements
         • Time Domain Measurements
 Radar Measurement Basics
                              Page 54
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                              Evaluating I/Q
                            Demodulator Errors




                                    Page 55
 Radar Measurement Basics
Polar Display -- Magnitude and
Phase Represented Together
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                                           a
                                       M
                                            g
                                                Phas
                                                e
                                                       0 deg




     • Magnitude is an absolute value
     • Phase is relative to a reference signal
 Animation
                                    Page 56
 Radar Measurement Basics
Signal Changes or Modifications
Click to edit Master subtitle style


                       ag
                   M
                            Phase
                                                                Phase
                                    0 deg                               0 deg
      Magnitude Change                                Phase Change




                                                                        0 deg

                               0 deg
      Both Change                                       Frequency Change
                                            Page 57
 Radar Measurement Basics
89640 Vector Signal Analyzer
Click to edit Master subtitle style
                                      • Tuners covering dc to 6.0
                                          GHz Frequency Range
                                      •   36-78 MHz bandwidth for
                                          broadband signal formats.
                                      •   >200MHz bandwidth with
                                          54832B Infiniium scope
                                      •   I/Q display formats
                                      •   Analog AM/FM/PM
                                          demodulation
                                      •   Time Gated measurements
                                      •   1.2Gbytes of capture
                                          memory
                                      •   Tight integration with ADS
                                          (PC based design
                                          applications).
                            Page 58
 Radar Measurement Basics
PSG Performance Signal Generator Family
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                    • 250 kHz to 20 or 40 GHz Frequency Range in Coax
                    • Extension to 110 GHz with the 83550 Series
                        Multipliers
                    •   High power
                    •   Excellent phase noise
                    •   AM/FM/PM and pulse modulation capabilities
                                           Page 59
 Radar Measurement Basics
Agenda
Click to edit Master subtitle style
         • Introduction
                  • Power Measurements
                  • Noise Measurements
                  • Component Test
                  • Evaluating I/Q Demodulator Errors
                  • Pulsed Component Measurements
                  • Time Domain Measurements
                  • Jitter Measurements
                                   Page 60
 Radar Measurement Basics
Agenda
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                            Pulsed Component
                              Measurements




                                   Page 61
 Radar Measurement Basics
 Pulsed Transfer Functions in the
 Time Domain
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                           Amplifier




                                       Page 62
Radar Measurement Basics
Agenda
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         • Introduction
                  • Power Measurements
                  • Noise Measurements
                  • Component Test
                  • Evaluating I/Q Demodulator Errors
                  • Pulsed Component Measurements
                  • Time Domain Measurements
                  • Jitter Measurements
                                   Page 63
 Radar Measurement Basics
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                            Time Domain
                            Measurements




                                 Page 64
 Radar Measurement Basics
Why Measure Pulse Parameters?
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 • PW determines resolving ability (small is better) -
   BW ~ 1/PW


 • PW affects average power (absolute range, large is
    better)                                            2
                                 4
                                     Pt G G
                                          t    r
                            R=                     3
                                     Pr (4 )


 • Unintentional AM and fast rise times can reduce
   the life expectancy of transmitter
 • PRI determines unambiguous range
                                          Page 65
 Radar Measurement Basics
 What are Important Pulse
 Parameters?
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                Risetime                Falltime




                      Pulse                          Pulse
                      Width                         Off Time
                                 Pulse Repetition
                                                      1
                                  Interval (PRI),
                                                     PRF




               Als            • Duty cycle
                o:            • Pulse shape (over and pre-
                                shoot, droop)
                              • Pulse width stability
                              • PRI stability              Page 66
 Radar Measurement Basics
Definition of Pulse Width
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     Average Power During On-time of Pulse


                                   -6dB




                Pulse Width

                            Pulse Repetition Interval



                                             Page 67
 Radar Measurement Basics
Time Domain Measurements
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   Envelop parameters        Modulation in the pulse
   • Rise time               • Unintentional
   • Fall time                   - AM to PM
   • Pulse width                 - Phase noise
   • Period                  • Intentional
   • On/off ratio                - Chirp
                                 - Barker coding
                                 - Frequency agility


                            Page 68
 Radar Measurement Basics
Measuring with a Digital
Oscilloscope
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 Advantages                 Considerations
 • General measurement tool • Aliasing
 • Wide bandwidth           • Dynamic range
 • Easy to understand       • Flatness
 • Option to post process   • Memory depth
   signal




                            Page 69
 Radar Measurement Basics
Time Domain Measurements
Click to edit Master subtitle style
                                                                                                      PULSED                   Antenna
                                                                                    RF     PREDRIVER POWER    DUPLEXER
                                         COHO              BPF    AMP               BPF      AMP    TRANSMITTER




                                                        STALO                    PRF              PULSE            RECEIVER
                                                                              GENERATOR         MODULATOR         PROTECTION

                                     Transmitter/Exciter

                                                                                                                          LNA

                                                VIDEO
                                                                                          FREQUENCY
                             ADC   S/H    LPF    AMP                                       AGILE L.O.


                                                                   o
                                                                 0
 DI
    SP          Doppler            COHO LIMITER LPF              SPLITTER
         LA
           Y     and
                Range
                 FFT                                       o            2nd    IF                    1st
                                                         90                                                  IF
               Processor                                                IFA   BPF                    IFA    BPF

                                                                                              2nd
                                                                                              L.O.
                             ADC   S/H   LPF    VIDEO
                                                 AMP
                                                                                     Receiver/Signal Processor




                                                           Page 70
  Radar Measurement Basics
Infiniium Oscilloscope
Click to edit Master subtitle style


                                      • 4 channels
                                      • Up to 64 MB deep
                                        memory
                                      • Up to 40 GSa/s
                                        sample rate/channel
                                      • Infiniium award-
                                        winning usability
                                      • Full upgradeability
                            Page 71
 Radar Measurement Basics
Agenda
Click to edit Master subtitle style
         • Introduction
                  • Power Measurements
                  • Noise Measurements
                  • Component Test
                  • Evaluating I/Q Demodulator Errors
                  • Pulsed Component Measurements
                  • Time Domain Measurements
                  • Jitter Measurements
                                   Page 72
 Radar Measurement Basics
Click to edit Master subtitle style




                                Jitter
                            Measurements




                                 Page 73
 Radar Measurement Basics
What is Jitter?
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                   Threshold
     (a)




      (b)          Threshold


                                Jitter       -creates ambiguity in threshold
                                              crossing


                    Threshold
      (c)
                                   Noise




                                           Page 74
 Radar Measurement Basics
  Jitter Function
 Click to edit Master subtitle style
   Ideal Pulse
          Train




                                                            Jitter signal viewed at
                                                            instants in time




Jitter function
                                                            Jitter magnitude
                              t1        t3     t4      t5
                                   t2

                                             Page 75
   Radar Measurement Basics
 What is Jitter?
   • to is the Master a timing event of a signal from its ideal position.
ClickJitter edit deviation of subtitle style
             Ideal clock:     sin(2π f c t )



          Jittered clock: sin (2π f c t + 4 π sin( 10 2π f c t ) )
                                          3
                                                    1




               Jitter:        4
                              3   π sin( 10 2π f c t )
                                          1



                   2
                   3   UI



                         •
                      This is the traditional description of jitter,
         •   commonly referred to Time Interval Error (TIE), or phase jitter.


                                                    Page 76
Radar Jitter Measurement
Click to edit Master subtitle style

               PRI Reference
                                                                   Trigger


                                                                    Digitizing
                               Crystal Detector                    Oscilloscope
      PULSED
                                                  Pulse Envelope
      RADAR                                                        Ch1




 Jitter
Source




                                    Page 77
 Radar Measurement Basics
Time Interval vs. Time Profile
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                                                 Peak-to-Peak Jitter Amplitude


      Time
   Interval


                                                           3.8 ns




                        17.9 KHz

                                                            Time

                Jitter Periodic Rate


                                       Page 78
 Radar Measurement Basics
Histogram of Clock Period
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                                   Probability Analysis
           % Probability




                                                                  Jitter Distribution




                                                                                 Period
                            MIN   -σ      MEAN         +σ   MAX

                                       Peak-to-Peak

                                                 Page 79
 Radar Measurement Basics
Histogram of Edge Jitter
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                           Page 80
 “Real World” Jitter is Complex
Jitter is composed of random
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and deterministic components

    Random Jitter (RJ) is
    unbounded
     •   Due to thermal noise, shot
         noise, etc.
     •   Follows Gaussian
         distribution
     •   Requires statistical
         analysis to be quantified
     •   RJpp = 14.1 x Jrms for 10-
         12 BER                                 DJ
    Deterministic Jitter (DJ) is
    bounded and composed
    of:
     •   Duty-Cycle-Distortion        RJ
         (DCD)
                                      Page 81
     •   Inter Symbol Interference
         (ISI)
 Jitter Probability: BER

   pk − pk=J
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 J             deterministic         n ×σ random
               =




                           Page 82
 How Do Real Time Scopes Measure
Jitter on Data?
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    NRZ
    Serial
     Data

Recovered
    Clock

   Jitter
   Trend

     Jitter                            Units in Time
 Spectrum
                                       Units in Time
     Jitter
Histogram




                            Page 83
Agilent EZJIT Jitter Measurement
Application
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                                      Signal

                                      Histogram


                                      Trend


                                      Spectrum




                           Page 84
Total Jitter Components
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                 TJ                       • TJ: Total Jitter (Convolution of RJ &
                                             DJ)

                                          • RJ: Random Jitter (rms)
 Bounded (p-p)        Unbounded (RMS)

            DJ        RJ                  • DJ: Deterministic Jitter (p-p)
                                                   PJ: Correlated &
                                                   uncorrelated Periodic Jitter
                                                   due to cross-talk and EMI
  PJ DCD ISI                                       DCD: Duty Cycle Distortion
                                                   due to threshold offsets and
                                                   slew rate mismatches
                                                   ISI: Inter-Symbol Interference
                                                   due to BW limitation and
                                                   reflections
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  Where Does Jitter Come From?
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  Transmitter                                                       Receiver
                                         Media


                                •Lossy interconnect (ISI)
                                •Impedance mismatches (ISI)
                                •Crosstalk (PJ)



 •Thermal Noise (RJ)                                          •Termination Errors (ISI)
 •Voltage Offsets (DCD)                                       •Thermal Noise (RJ)
 •Power Supply Noise (RJ, PJ)                                 •Incorrect Threshold (DCD)
 •On chip coupling (PJ)                                       •Power Supply Noise (RJ, PJ)
                                                              •On chip coupling (PJ)


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Into this…
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                           Page 87
Questions and Answers
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                           Page 88

				
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