What Have You Been Missing In Your Pulsed VNA Measurements?

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

Confidence • on the cutting edge Pulsed Measurements

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

Common Pulse Applications • 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)

Radar Courtesy of LCRS Courtesy of Telematics News Courtesy of Raytheon

Radar Radar trends • Narrower pulses • 1 us, 150 m • 50 ns, 7.5 m • Wide range of PRF • Lower, longer range • Higher, shorter • Higher frequencies • Antenna size, bandwidth, smaller target sizes • Key measurement parameters: • Min pulse width/resolution, record length, range of PRFs, frequency range

Pulsed IV (and RF) Electrical • Key measurement parameters: • Pulse profile and min measurement width, point-in-pulse resolution, pulse-to-pulse and PRF range • Used with TWTAs to reduce power consumption • Used at wafer-level to avoid thermal effects • Memory \trapping effects Thermal

Pulse Characteristics and Definitions

Measurement Overview • Three types of stimulus: * * • Three types of measurements: Pulse Profile (PP) Point-in-Pulse (PIP) Sweep time Sweep freq or power Pulse-to-Pulse (P2P) Sweep time

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)

Time – Frequency Domains

Traditional Trade-offs Wideband Method Trade-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.

Traditional Trade-offs Dynamic range degradation = 20*log[duty cycle]  1% duty cycle = 40 dB D/R reduction! Narrowband Method Trade-offs: • Dynamic range penalty • No pulse-to-pulse capability

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 View 2.5 ns resolution 15 ns resolution What have you been missing?

The True View Example: 100 ms PRI (100 µs, 900 µs period), 10 ns resolution, 30 MHz IFBW Record lengths up to 500 ms -- At full resolution!

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

Measurement Confidence • Simple measurement configuration • Adjustments for each receiver

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 Independent IF Rcvr Windows • Delay start of b2 measurement to properly align S21 result • Measurement results may identify unexpected behavior • For example, there may be measurement delays (from group delay, long test cables, …) which can affect ratio measurements

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 • 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

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, …)

What Have You Been Missing In Your Pulsed VNA Measurements? 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

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What Have You Been Missing In Your Pulsed VNA Measurements?