1 EuMW Seminars 2013 What Have You Been Missing In Your Pulsed VNA Measurements? 8 Oct 2013 13:00h - 13:40h Presented by: Bob Buxton.

1EuMW Seminars 2013EuMW Seminars 2013

What Have You Been Missing In Your Pulsed VNA Measurements?

8 Oct 201313:00h - 13:40h

Presented by: Bob Buxton

2EuMW Seminars 2013

on the cutting edgeConfidence

PulsedMeasurements

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Agenda• Background

• Applications• Measurement Overview• Common Test Challenges

• Pulse Measurement Methodologies• Wideband method• Narrowband method• High-Speed digitizer method (VectorStar’s innovative architecture)

• Measurement Tips and Considerations• Calibration• Minimizing Uncertainties

• Summary

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• Measure the reaction of a DUT to a pulsed RF stimulus– E.g., Radar: transmitter, receiver, or both

• Measure the reaction of a DUT to pulsed IV (and pulsed RF?)– High power density semiconductors (SiC, GaN)– Traveling-wave-tube amplifiers (TWTAs) – Must synchronize with (ext sync) or control DC bias (pulse gen)

• Part of active device test suite– S-parameters– 1 dB compression point– NF, higher order distortion products, harmonics – IMD, IP3 (third-order intercept point)

Common Pulse Applications

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Radar

Courtesy of RaytheonCourtesy of Telematics News

Courtesy of LCRS

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Radar

• Key measurement parameters:– Min pulse width/resolution, record length, range of PRFs, frequency range

Factor Radar Characteristic AffectedPulse shape Range accuracy, range resolutionPulse width Range resolution, maximum range, minimum

detection range

Pulse repetition frequency Maximum unambiguous range, detection probability

Fundamental frequency Directivity, target resolution, propagation loss, size of equipment

Chirp frequency bandwidth Range resolutionChirp pulse ripple/time sidelobes Target masking, range resolutionScan rate and beamwidth Probability of detection, angular resolutionReceiver sensitivity Maximum detection rangeTransmitter power Maximum detection range, physical sizeAverage gain Maximum detection rangeRadar cross section Maximum detection range

Radar trendsNarrower pulses

1 us, 150 m50 ns, 7.5 m

Wide range of PRFLower, longer rangeHigher, shorter

Higher frequenciesAntenna size, bandwidth, smaller target sizes

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• Used with TWTAs to reduce power consumption

• Used at wafer-level to avoid thermal effects – Memory \trapping effects

Thermal

Pulsed IV (and RF)

• Key measurement parameters:– Pulse profile and min measurement width, point-in-pulse resolution, pulse-to-

pulse and PRF range

Electrical

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• Summary

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Pulse Characteristics and Definitions

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• Three types of measurements:

Pulse Profile (PP) Point-in-Pulse (PIP)

Pulse-to-Pulse (P2P)

Sweep time

Sweep time

Sweep freqor power

• Three types of stimulus: Measurement Overview

* *






• Summary


Common Test Challenges• Too many test method trade-offs

• Need for better analysis tools

• Monitor pulse behavior over longer times

• Eliminating measurement setup errors

• Timing and synchronization issues(in measurement or calibration)






• Summary


Time – Frequency Domains


Traditional Trade-offsWideband MethodTrade-off: minimum pulse width limitations

Historically, wideband pulse measurement is used when most pulse energy is contained in the receiver BW. As pulse widths narrow (e.g., 1 µs), users are forced to move to narrowband techniques.






• Summary


Traditional Trade-offsNarrowband MethodTrade-offs:− Dynamic range penalty− No pulse-to-pulse capability

Dynamic range degradation = 20*log[duty cycle] 1% duty cycle = 40 dB D/R reduction!








MS4640B now with:• Option 035 IF Digitizer• Option 042 PulseViewTM

• Pulse Modulator Test Sets (required for RF pulsing)


Eliminate Trade-offs!

• Option 035 IF Digitizer enables– 200 MHz Receiver bandwidth– Measurement resolution as fine as 2.5 ns– Independent measurement IF receiver windows– 500 ms record lengths








The True View2.5 ns resolution

15 ns resolution

• What have you been missing?








The True View

At full resolution!

Example: 100 ms PRI (100 µs, 900 µs period), 10 ns resolution, 30 MHz IFBW

Record lengths up to 500 ms --








Measurement Confidence• Visual representation of signals and

measurements

• Simple generator configuration– Varying types of pulses generated• Singlet• Doublet• Triplet• Quadruplet• Burst

– Change labels for better test descriptors


• Simple measurement configuration– Adjustments for each receiver

Measurement Confidence


Measurement Confidence• Use Zoom Marker to double

check test setup• Drag vertical lines for start and

stop zoom area• Drag vertical lines as time

markers


Industry-first Instant Results

• Make measurement adjustments and see the results instantly• No need to toggle back

and forth between configuration windows








Coupled IF Receiver Windows

• Measurement results may identify unexpected behavior– For example, there may be measurement delays (from group delay,

long test cables, …) which can affect ratio measurements

• Delay start of b2 measurement to properly align S21 result

Independent IF Rcvr Windows






• Summary


Calibration• Power Calibrations• Receiver Calibrations• User RF Calibrations– No stimulus pulsing– Stimulus pulsing– Receive-side modulation/gating


Minimizing Uncertainties• Time• Shaping• Calibration• Minimizing uncertainties– Increase averaging or reduce IFBW– Maximize power (while avoiding compression)– Filtering


Summary• Background





Equipment Selection Criteria• IF bandwidth – sampling rate• Min measurement and timing resolution• Measurement method trade-offs (e.g., dynamic range reduction)

• # of pulse generators available– Pulse generation signal formats available (e.g., doublets, bursts, …)– Min pulse width

• Pulse modulator performance (e.g., on-off ratio, rise-time, …)


• Innovative high-speed digitizer architecture

• Industry’s highest resolution measurements

• Longest record lengths

• Independent measurement receiver windows

• Intuitive graphical configuration tool

• Instant results on measurement parameter changes

What Have You Been Missing In Your Pulsed VNA Measurements?

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FOR ANSWERS!

1 EuMW Seminars 2013 What Have You Been Missing In Your Pulsed VNA Measurements? 8 Oct 2013 13:00h - 13:40h Presented by: Bob Buxton.

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