Fundamentals of Arbitrary. Waveform Generation

Transcription

1 Fundamentals of Arbitrary Waveform Generation

2 History Applications Key Specifications Optimization Signal fidelity and dynamic range Embedding and de-embedding Waveform generation and automation software Real-world examples 2

3 From analog to digital signal generation April 1988 Sep Sep April 1988 Signal Generator with internal and external modulation capabilities Arbitrary Waveform Synthesizer with digital architecture and analog output, 50 MHz Sep 2015 Arbitrary Waveform Generator with 92 GSa/s 32 GHz analog bandwidth HP 618 HP 8770A back view Keysight M8196A 3

4 Symbol Rate B I G D ATA D E M A N D D R I V E S T E C H N O L O G Y C H A N G E S Increase Symbol Rate Modulation Maximize Bits per Symbol Multi level signaling in digital links, Maximize # of carriers 4

5 AWG offers wider modulation BW Generate multiple carriers simultaneously Fast hopping BUT: less dynamic range Signal Generator AWG offers more flexibility, e.g. different pulse shapes or adding pre-distortion BUT new waveform required for every pulse parameter change AWG offers more flexibility, e.g. custom spectral shapes, notches, narrowband noise, etc. BUT: not as random as true noise sources AWG has typically a superset of functionality BUT is typically more expensive (for same bandwidth) Noise Source Function/ Arb Generator AWG BERT/ Pattern Generator Pulse Generator AWG offers more flexibility, e.g. variable rise times, multi-level signals, pre-distortion BUT can not do true RJ and limited pattern length No error detector included 5

6 Highest bandwidth requirements Highspeed digital (incl. PAM4) you name it A/D (Radar, EW) Highest dynamic range requirements Coherent Optical AWG Wideband RF & Satellite Physics, THz research DPD; amplifier test HDMI / CPHY 5G, new modulation formats 6

7 T H E M O S T V E R S AT I L E S I G N A L S C E N A R I O G E N E R AT O R P O S S I B L E It demonstrates the flexibility you can have with an AWG. Whatever you can described mathematically you can generate. you are only limited by your imagination! 7

8 I M P O R TA N T AW G C R I T E R I A Memory size -> playtime Dynamic range -> signal quality basic AWG architecture Software generates arbitrary signal Waveform Memory DAC Reconstruction Filter External or embedded PC Depends on application Sampling rate / bandwidth 8

9 1 ST K E Y S P E C P L AY T I M E Waveform Memory Memory sample rate = play time 256 ksa 64 GSa/s = 4 µs data clock DAC Reconstruction Filter Waveform is defined in samples, which defines values in a given time interval. Outputs discrete output voltage levels => allows different waveforms 9

10 Increasing Memory sample rate = playback time Sample Rate Playback time degrades 10

11 H O W D O W E A C H I E V E L O N G E R P L AY T I M E S? Loop 1 time Loop 45 times Loop 1 time Loop 33 times Waveform segments are stored in memory Waveform Memory Sequencer Memory data clock DAC The Waveform Sequencer is where the waveform segments are arranged (sequenced) to create the desired waveform Memory sample rate playback time 11

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13 2 ND K E Y S P E C S A M P L E R AT E Waveform Memory data clock DAC Reconstruction Filter Sample rate / clock rate sample access rate Determines max frequency component of the signal, given adequate analog bandwidth 14

14 2 ND K E Y S P E C S A M P L E R AT E Waveform Memory data clock DAC Reconstruction Filter f s sampling frequency f c highest frequency contained in the signal Sample rate / DAC sample rate Sample Rate needs to be twice the frequency output f s 2 f c 15

15 sampling factor 3 f s 2 f c f s sampling frequency f c highest frequency contained in the signal sampling factor 1.5 sampling factor 2 example aliasing The sampling frequency should be at least twice the highest frequency contained in the signal 16

16 Theoretical Output data clock DAC Real Output 17

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18 Waveform Memory data clock DAC Reconstruction Filter Roll off limits our bandwidth to typ 40 % of sample rate 19

19 data clock DAC Reconstruction Filter 20

20 P U L S E S H A P E A F F E C T S S I G N A L W AV E F O R M Raised cosine a = 0.05 Raised cosine a = 0.35 Raised cosine a = 1.0 rectangular 21

21 I N T E G E R V S. F R A C T I O N A L R E - S A M P L I N G Integer Re-sampling Fractional Re-sampling

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23 3 RD K E Y S P E C D Y N A M I C R A N G E Waveform Memory The more bits, the better the signal resolution data clock DAC Reconstruction Filter Number of bits Sample rate Determines dynamic range Each bit in DAC doubles the voltage resolution ~ 6 db per bit 24

24 E F F E C T I V E N U M B E R O F B I T S O R E N O B Impairments limit AWG dynamic range! SFDR = Spurious Free Dynamic Range SINAD = ratio of the total signal power level (Signal + Noise + Distortion) to unwanted signal power (Noise + Distortion) Images Sample Clock Feedthrough Harmonics Spurious Noise Floor ENOB = SINAD 10log log2 = SINAD

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26 U S I N G S - PA R A M E T E R S O R M E A S U R E D I N - S Y S T E M Transmitter (TX) TP1 TP2 TP3 Channel Receiver (RX) 27

27 U S I N G S - PA R A M E T E R S O R M E A S U R E D I N - S Y S T E M Transmitter (TX) TP1 TP2 TP3 Channel Receiver (RX) 28

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29 D I F F E R E N T S O F T W A R E I N T E R F A C E S F O R D I F F E R E N T A P P L I C AT I O N S IVI / SCPI and more 30

30 Suggested software for all digital applications Single GUI for M8020A & AWG Hardware General NRZ & PAM4 on M8195A/96A C-PHY on M8190A C-PHY, D-PHY on M8195A HDMI on M8195A 31

31 The Optical Modulation Generator Software 81195A works in conjunction with the M8195A 4-channel AWG to generate dual-i/q signals up to 32 Gbaud with up to 8 GSym per channel using a single M8195A module in realtime encoding mode It will also support four M8195A modules in waveform mode, synchronized by an M8197A module The Optical Modulation Analyzer (N4381A, N4382A) will be updated to analyze those optical signal properties 32

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33 e.g. A/D and communications, wherever excellent signal quality is needed 34

34 32 GBaud 128 QAM : 224 Gb/s generated by M8196A 35

35 R I S E T I M E & J I T T E R Tr/Tf=7ps 20%-80% RJ = 110 fs(rms) With digital pre-distortion w/ 32G PRBS7, 86108B 36

36 56 GBaud PAM4 = 112 Gb/s 37

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38 P R O P R I E TA R Y T E C H N O L O G Y - U N I Q U E P E R F O R M A N C E Choose the performance you need High Resolution Wide Bandwidth PXIe based AWG AXIe based AWG 81150A/60A PPG/AWG 81150A/60A PPG/AWG 120 MHz / 330MHz analog bandw 1 or 2 channel, differential Outputs DDS based M3201A 500MSa/s 200 MHz analog bandwidth 16 bit, 2/4 channels, progr. FPGA M3202A 1 GSa/s 400 MHz analog bandwidth 14 bit, 2/4 channels, progr. FPGA M9330/31A 1.25 GSa/s 500 MHz analog bandwidth 15 bit / 10 bit, 65dBc/50dBc, 2 ch. M8196A 92 GSa/s 32 GHz analog bandwidth 8 bit, up to 4 channel M8195A 65 GS/s 25 GHz analog bandwidth 8 bit, up to 4 channel M8190A 12 GSa/s 5 GHz analog bandwidth 14 bit/12 bit, 1 or 2 channels 39

39 M8190A 8/12 GSa/s 5 GHz BW 1 or 2 channels Digital up conversion 12/14 bit resolution SFDR up to 90 dbc Applications Radar / EW Satellite M8195A 65 GSa/s 25 GHz BW 1, 2, or 4 channels DSP for coherent optical 8 bit resolution 16G points Applications 32 GBaud PAM4 Coherent optical RF with > 4 GHz modulation BW M8196A 92 GSa/s 32 GHz BW 1, 2, or 4 channels 8 bit resolution 512K points Applications 56 GBaud PAM4 Coherent optical 40

40 Link to AWG application notes: Keysight YouTube Channel: To sign up for future webcast and see recordings of our past webcasts, please visit the Keysight RF & Digital Learning Center: 41

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