Pulsed S-Parameter Measurements using the ZVA network Analyzer

Transcription

1 Pulsed S-Parameter Measurements using the ZVA network Analyzer 1 Pulse Profile measurements

2 ZVA Advanced Network Analyser 3

3 Motivation for Pulsed Measurements Typical Applications Avoid destruction of DUT due to thermal effects Power amplifiers not designed for continuous operation Lack of heat sinking (e.g. on wafer components) Measure under real conditions with wireless communications For example. GSM power amplifiers under burst conditions Burst mode of TDMA systems and components Requirements for Radar and Antenna Measurements Active array antennas operate in pulsed mode Scattered pulse incorporates information 4

4 Motivation for Pulsed Measurements Typical Measurements Output power versus frequency and power S-Parameter versus frequency and power Typically S11 and S21 Occasionally S12 and S21 also required Pulse profile versus time at a fixed frequency Power and S21 versus time 5

5 Fundamentals of Pulsed Measurements What is a RF-Pulse in Time Domain x = A RF pulse is a multiplication of a rectangular pulse with a CW-RF signal 6

6 Fundamentals of Pulsed Measurements The Spectrum of a RF-Pulse PRF := Pulse Repetition Frequency 7

7 Fundamentals of Pulsed Measurements What is a RF-Pulse in Frequency Domain Multiplication in time domain = convolution in frequency domain A A A t t t A x A = A f f c f f c f spectrum of pulse is shifted by frequency of CW signal 8

8 Fundamentals of Pulsed Measurements Types of Pulsed Measurements NWA s data acquisition time/point > pulse width Measurement during several pulses narrow bandwidth technique (Average) Measurement verses power or frequency NWA s data acquisition time/point < pulse width one data point during one pulse wide bandwidth technique (point in pulse) Measurement verses power of frequency NWA s data acquisition time/point << pulse width several data points during one pulse pulse profile technique Measurement of pulse verses time settling time settling time Measurement time / point Measurement time / point data points Measurement time / point time time time 9

9 Averaged Pulsed Measurements Measuring the Average (DC Value) P P AVG T Pmin P f c B IF B IF := 1/IFBW f 10

10 Averaged Pulsed Measurements Frequency or power swept measurements Measurement at one frequency or power level during several pulses the DC-Value of the Pulse Envelope A P AVG #f1 P AVG #f2 P AVG #f2 multiple pulses f 1 f 1 f 2 f 2 f 3 t Sampling time f 1 Sampling time f 2 11

11 Averaged Pulsed Measurements Dynamic Range considerations Pulse Desensitisation Measurement example: P= 0 dbm T on = 1 µs T P = 10 µs ( T ) Pulse Width Duty Cycle = on Pulse Period T p T on T p CH1 b2 db MAG 10 db/ REF 0 dbm 1: dbm 20 dbm - 1 MHz +1 MHz 10 GHz 10 db/ 1 20 db á 0 dbm EXT FST CPL = 20*log(1/10) = -20 db FI L 3k - 80 dbm 500 khz/ CENTER 10 GHz SPAN 3 MHz 12

12 Averaged Pulsed Measurements Spectral Nulling Necessary with previous ZVM/K family Placing the Nulls of the IF filter on the first harmonic Blue trace: Spectrum of T = µs Tone spacing khz CH1 b1 db MAG - 90 dbm - 10 dbm 1 : d Bm CH2 b2 db MAG - 80 dbm - 20 dbm 12 0 d Bm + 8 k Hz 1 GHz 2 : d B k Hz 3 : d B k Hz EXT FST Red trace: Shape of 3 khz IF-filter with nulls at khz offset 1 0 d B/ FI L dbm 2 khz/ 2 khz/ CENTER 1 GHz CENTER 1 GHz SPAN 20 khz SPAN 20 khz 13

13 Averaged Pulsed Measurements ZVA s High Selective Filter No Nulling Required Trc1 a1 db Mag 10 db / Ref 20 dbm a Ch1 Arb Center 1 GHz Pwr 20 dbm Span 500 khz Trc2 a1 db Mag 10 db / Ref 20 dbm a Ch2 Arb Center 1 GHz Pwr 20 dbm Span 500 khz 14

14 Averaged Pulsed Measurements Example of desensitisation on a frequency sweep RBW=100Hz High Selective Trc1 Mem4[Trc1] Mem5[Trc1] Mem6[Trc1] 0 S S21 S21 S21 S21 db Mag db Mag db Mag db Mag 15 db / 15 db / 15 db / 15 db / Ref 0 db Ref 0 db Ref 0 db Ref 0 db Mkr 1 Mkr 1 Mkr 1 Mkr GHz GHz GHz GHz db db db db -45 Duty Cycle 1µ s = 1 ms = 0.1% Mkr 1 ~ -65dB 1µ s Duty Cycle = = 1% 100µ s 1µ s Duty Cycle = = 10% 10µ s Duty Cycle = CW = 100% Mkr 1 Mkr 1 Mkr 1 Ch1 Center 2.22 GHz Pwr 10 dbm Span 200 MHz 4/24/2007, 11:29 AM ~ -100dB ~ -120dB ~ -140dB 15

15 Point in Pulse Measurements Frequency or power swept measurements Measurement at different frequencies or power levels in different pulses (point trigger mode with trigger delay τ) Each point represents a different frequency or power A t f 1 f 2 f 3 f 4 f 5 t τ f 1 f 2 f 3 f 4 f 5 16

16 Point in Pulse Measurements Measurement during one pulse data sampling happens during the pulse ON state sampling time 1/IFBw 1 / IFBW < t on => IFBW > 1/ t on (pulse length) maximum IF bandwidth limits the minimum pulse length ZVR: 35 µs (26 khz) ZVB: 3 µs (500 khz) ZVA/T: 1,8 µs (1 MHz) ZVA/T: 0.4 µs (5 MHz) with ZVA-K17 option settling time Measurement time / point time (times are typical pure data acquisition time w/o any data processing time) e.g. CW-sweep, triggered synchronization 17

17 Point in Pulse Measurements Point in Pulse Measurements with ZVA-K17 ZVA-K17 For Point in Pulse measurement with pulse width < 430 ns (230 ns) IF bandwidth 5 MHz (10 MHz unspecified) CW sweep (kind of pulse profile) with resolution of 1,9 us (1,6 us) 18

18 Point in Pulse Measurements Time per Point The Limitation settling time data sampling data processing transfer of instr. data freq. settling pow. settling Time per Point: Frequency Sweep: 1µs + 4µs + (3µs...15µs) + (1 2) / IF Bw + 2µs CW Sweep: (1 2) / IF Bw + 1,5µs 19

19 Point in Pulse Measurements Limitations for Pulse Profile Measurements Resolution limited by time for data sampling and data processing Sampling 1 MHz IFBw 1,8 µs Sampling 5 MHz IFBw 400 ns (ZVA-K17) Data processing time 1,5 us (CW Sweep) Time resolution = sampling time + processing time > 1,9 us (5 MHz IFBw) 20

20 Pulse Profile Measurements Narrowband Solution Chopping the pulse at different positions with floating pulse delay Average pulse measurement of the chopped pulses provides magnitude and phase information for the chopped section Pulse profile has to be reconstructed pulse envelope chopped pulse floating delay t measurement time (1/IFBW) 21

21 Pulse Profile Measurements Narrowband Solution Time consuming setup Change of pulse shape requires recalibration Requires a periodical, stable pulse signal No real time measurement Low dynamic range for low duty cycles 22

22 Pulse Profile Measurements Rohde & Schwarz Solution: SSRAM Mode 23

23 Pulse Profile Measurements Rohde & Schwarz Solution: SSRAM Mode Sampling data of all wave quantities are stored without filtering into a dedicated memory Sampling rate = 12,5 ns (system clock of 80 MHz) At the end of data recording, digital signal processing e.g. filtering is performed not by the DSP but by the software offline Advantages: No delay by processing time between sampling of to data points No limitations for suitable IF filter 24

24 Pulse Profile Measurements Continous Recording into the SSRAM Memory Trc1 b2 db Mag 10 db / Ref -40 dbm 1 b2 TRG Ch1 Profile Start-500 ns Freq 1 GHz Pwr 0 dbm Stop 500 ns 25

25 Pulse Profile Measurements Features of SSRAM Mode Memory of 256 kb 256*1024*12,5ns = 3,2768 ms 3,2 ms of total recording time for S-parameters Trigger event sets t = 0 Continious recording of data Behaviour before trigger event can be analysed Fast display repetition rate for pulse profile => Tuning possible 26

26 Pulse Profile Measurements The Bandwidth Does not define the resolution Resolution always 12,5 ns (sampling rate of ZVA) Defines: Rise time ( 1/IFBw) Maximum ripple frequency on the pulse roof Comparable with the bandwidth of an oscilloscope The Pulse Profile mode works similar as an oscilloscope with a time resolution of 12 ns and a bandwidth of e.g. 30 MHz 27

27 Pulse Profile Measurements The IF Filters for Pulse Profile 1MHz, 2 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz, 30 MHz lower bandwidths not necessary, as normal time or CW sweep can be used slight overshoot of pulse response 10 MHz, 15 MHz no overshoot 20 MHz < 3% 30 MHz < 10% May lead to small error for output power measurement Completely compensated for ratio measurements as b2/a1 or S-parameters because of rationing 28

28 Pulse Profile Measurements The Rise Time of the Pulse Profile Filters RBW_10MHz b1 Lin Mag 1 mw/ Ref 0 W b1 TRG 8 7 Ref ns µw Mkr ns mw 1 RBW_15MHz b1 Lin Mag 1 mw/ Ref 0 W 7 TRG b1 Ref ns µw 8 Mkr ns mw Mkr Mkr Ref RBW = 10 MHz Rise Time = 57.5 ns Ref RBW = 15 MHz Rise Time = ns 0 0 Ch1 Profile Start -50 ns Freq 1 GHz Pwr 0 dbm Stop 450 ns RBW_20MHz b1 Lin Mag 1 mw/ Ref 0 W b TRG Ref ns µw Mkr ns mw 3 Ch2 Profile Start -50 ns Freq 1 GHz Pwr 0 dbm Stop 450 ns RBW_30MHz b1 Lin Mag 1 mw/ Ref 0 W b1 TRG Ref ns µw 8 Mkr ns mw Mkr 1 5 Mkr Ref RBW = 20 MHz Rise Time = 35.0 ns Ref RBW = 30 MHz Rise Time = 30.0 ns 0 0 Ch3 Profile Start -50 ns Freq 1 GHz Pwr 0 dbm Stop 450 ns 4/20/2007, 11:12 AM Ch4 Profile Start -50 ns Freq 1 GHz Pwr 0 dbm Stop 450 ns 29

29 Pulse Profile Measurements Pulse Profile of a 100 ns DUT Trc1 b2 db Mag 10 db / Ref 0 dbm b TRG Trc3 a1 db Mag 10 db / Ref 0 dbm Ch1 Profile Start -100 ns Freq 1 GHz Pwr 0 dbm Stop 1 µs 1 b2 wave shifted with respect to reference a2 wave by group delay of 100 ns Trc2 S21 db Mag 10 db / Ref -10 db S21 TRG S21 after ratioing Ch1 Profile Start -100 ns Freq 1 GHz Pwr 0 dbm Stop 1 µs 30

30 Pulse Profile Measurements Pulse Profile of a 100 ns DUT Trc1 b2 db Mag 10 db / Ref 0 dbm b2 TRG Trc3 a1 db Mag 10 db / Ref 0 dbm 1 b2 and S21 after mathematical delay of 100 ns Ch1 Profile Start -100 ns Freq 1 GHz Pwr 0 dbm Stop 1 µs Trc2 S21 db Mag 10 db / Ref -10 db S21 TRG Ch1 Profile Start -100 ns Freq 1 GHz Pwr 0 dbm Stop 1 µs 31

31 Pulse Profile Measurements Pulse Profile Test with ZVA and SMR AUX User control for list mode Trigger IEEE/LAN REF Generation of pulsed RF signal with pulse generator Can be controlled by ZVA Signal generator with Pulse modulator Pulse Profile and Frequency/Power sweep possible Pulsed RF Source DUT Internal coupler of the ZVA determines wave quantities 32

32 Pulse Profile Measurements Block Diagram for Pulsed Stimulus Reflectometer of ZVA Pulsed source fed in front of coupler Pulsed reference signal Calibrated S11 and S21 measurements Calibration independent of duty cyle Signal generator with Pulse modulator Frequency and power sweep possible 33

33 Pulse Profile Measurements ZVA, Arb Waveform Generator and Pulse Modulator Arbitrary Waveform Generator RF Switch DUT 34

34 Pulse Profile Measurements Pulse Profile with Pulsed DUT Trc4 S21 db Mag 5 db / Ref -5 db S Trc8 S11 db Mag 0.2 db / Ref -3 db Mkr 1 Mkr ns ns 3 of 3 (Max) db db Mkr DUT Mkr Amp: On/Off -3.8 Pulsed DC supply Ch2 Profile Start 120 ns Freq 2 GHz Pwr 0 dbm Stop 1.3 µs 8/18/2006, 1:23 PM 35

35 Accuracy: CW Mode, Point in Pulse, Pulse Profile Trc1 Mem6[Trc1] S12 db Mag 0.1 db / S12 db Mag 0.1 db / S12 Mkr GHz Mkr GHz -5.8 Mkr 1 Mkr Ref 1- Ref - db db Ch1 Start 2Pwr GHz 0 dbm Stop 8 GHz Trc5 Mem9[Trc5] S S11 db Mag 2 db / Ref -36 db S11 db Mag 2 db / Ref -36 db Mkr 1 Mkr 1 Trc2 Mem7[Trc2] S21 db Mag 1 db / S21 db Mag 1 db / S21 Mkr GHz Mkr GHz Mkr Ref Ref -6. db db Ch1 Start 2Pwr GHz 0 dbm Stop 8 GHz Ca? Mkr GHz db Mkr GHz db Trc10 Trc11 S21 TRG Trc3 Mem8[Trc3] S S22 db Mag 2 db / S22 db Mag 2 db / Mkr 1 Mkr 1-38 Mkr GHz db Mkr GHz db Ref -363 Ref -36 Ch1 Start 2Pwr GHz 0 dbm Stop 8 GHz S21 db Mag 5 db / Ref -15 db S11 db Mag 10 db / Ref 0 db Mkr 1 Mkr 1 Mkr ns Mkr ns Ca? Ca? db db Traces: Point in Pulse Mem Traces: CW Mode Pulse Profile Ch1 Start 2 GHz Pwr 0 dbm Stop 8 GHz 11/3/2006, 7:37 AM Ch2 Profile Start Freq ns GHz Pwr 0 dbm Stop 1 µs 36

36 Pulse Profile Measurements Pulse Train with Changing Duty Cycle and Amplitude Trc1 a1 db Mag 10 db / Ref 0 dbm 1 a TRG M1 M2 M1 M µs µs dbm dbm Ch1 Profile Start µs Freq 1 GHz Pwr 0 dbm Stop 272 µs Trc2 S21 db Mag 5 db / Ref 25 db S21 TRG M 1 10 M2 5 M1 M µs µs db db Ch1 Profile Start µs Freq 1 GHz Pwr 0 dbm Stop 272 µs 10/4/2007, 5:57 PM 37

37 Pulse Profile Measurements Pulse Train with AM Modulation Trc1 b2 db Mag 5 db / Ref 0 dbm TRG b Trc3 a1 db Mag 10 db / Ref 0 dbm 1 Ch1 Profile Start -10 µs Freq 1 GHz Pwr 0 dbm Stop 1 ms Trc2 S21 db Mag 2 db / Ref 14 db TRG S Ch1 Profile Start -10 µs Freq 1 GHz Pwr 0 dbm Stop 1 ms 10/4/2007, 6:12 PM 38

38 Real and Imag signals Are displayed at the reference Pulse Profile Measurements Pulse Train with FM Chirp Modulation Trc1 Trc2 a a1 Real 2 mw/ Ref 0 W a1 Imag 2 mw/ Ref 0 W TRG 1 Trc3 Trc5 a a1 db Mag 10 db / Ref 0 dbm b2 db Mag 10 db / Ref 0 dbm TRG Mkr 1 Mkr 2 Mkr 1 Mkr 2 Mkr µs Mkr µs Mkr µs Mkr µs dbm dbm dbm dbm 2 The magnitude of the Reference a1 and Measure channel b2. B2 is time shifted, See next slide (DUT is a 50ns delay Line) Ch1 Profile Start Freq -2 µs1 GHz Pwr 0 dbm Stop 8 µs Ch1 Profile Start Freq -2 µs1 GHz Pwr 0 dbm Stop 8 µs Trc4 S21 db Mag 5 db / Ref 0 db Trc6 S21 Phase 45 / Ref 0 S TRG Mkr 1 Mkr µs Mkr µs Mkr 2 Mkr µs db Mkr 1 Mkr µs db Mkr 2 3 The S-Parameters can Be calculated for Both the magnitude and Phase from a1 and b2 Ch1 Profile Start -2 µs Freq 1 GHz Pwr 0 dbm Stop 8 µs 1/9/2008, 11:56 AM 39

39 Pulse Profile Measurements Pulse Profile Measurements with ZVA-K7 For Pulse Profile Measurement Includes ZVA-K17 For Point in Pulse measurements versus frequency and power Minimum pulse width 420 ns For Pulse Profile measurements with resolution of 12,5 ns and IFBw of 10 MHz Wider IFBw up to 30 MHz (unspecified) available beginning 2007, with upgraded ZVA hardware 40

40 Fundamentals of Pulsed Measurements Summery of Pulsed Measurements Average Pulse Measurement (App.-Note 1EZ52) Measurement versus power and frequency Minor requirements for NWA hardware (ZVA-K4, ZVA-B16) Point in Pulse Measurement (more accurate) Measurement versus power and frequency Requires sampling time < pulse width (ZVA-K4, ZVA-K17, ZVA-B16) Pulse Profile Measurement Measurement of the pulse versus time settling time Measurement time / point Measurement time / point data points time time Requires sampling time << pulse width (ZVA-K7, ZVA-B16) settling time Measurement time / point time 41

41 Thank You for your attention! Questions? 42