No More Pulse Tuning? A New Source Measure Unit May Surge LiDAR Testing Forward

April 27, 2020 by Cabe Atwell

Tektronix says they've simplified VCSELS testing by combining a high-speed current pulser with a DC source and measurement function.

What if you no longer had to deal with manual pulse output tuning? Tektronix has recently announced what it calls an "industry-first" technology that eliminates pulse tuning in an all-in-one form factor. What is this technology geared for? And how exactly does it work?


The Goal to Surge LiDAR Testing Forward

The new 2601B-PULSE System SourceMeter Pulser SMU was built with LiDAR in mind, specifically for testing vertical-cavity surface-emitting lasers (VCSELS). VCSELs are crucial for ranging LiDAR applications and critical automotive light detections.

2601B-PULSE 10 µsec Pulser/SMU

2601B-PULSE 10 µsec Pulser/SMU. Image used courtesy of Tektronix


Tektronix claims the SMU can effectively minimize device self-heating, which can lead to faulty measurements and equipment damage in optical devices. That said, Tektronix has also designed this SMU for LED testing, surge protection testing, and fault power management testing. It can also be helpful with characterizing semiconductor devices. 


Technology Breakdown

The company says that no matter the amplitude or pulse width, this new technology cuts the need for manual pulse output tuning. According to Tektronix, “the new system incorporates PulseMeter technology for sourcing current pulses as short as 10 μsec at 10 A and 10 V without the need to manually tune the output to match device impedance up to 3 μH.” 


The Basics

The new SMU (PDF of the datasheet) offers a 10 A at 10V at 10 μs pulse-width and full 1 MS/s digitizing capabilities to significantly boost productivity in a wide array of applications, including benchtop characterization and automated pulsed I-V production tests.


The new SMU's pulse characteristics

The new SMU's pulse characteristics. Image used courtesy of Tektronix

 It also offers built-in dual 1MS/sec,18-bit digitizers, which augment the pulser’s measurement function, allowing users to garner pulse-current and voltage waveforms together—without the help of a separate tool. 

Key features of the 2601B-PULSE System SourceMeter include dual 1-Megasample/second digitizers for high speed I/V pulse measurements (pulser function only), DC capability up to ±40 V at ±1.0 A at 40 W, and TSP-Link expansion. It also offers USB 2.0, LXI Core, GPIB, RS-232, LAN, and digital I/O interfaces, as well as a D-sub 25-pin digital I/O port for internal/external trigger signals and handler control.


Control Loop System

While other SMUs require pulse tuning to minimize overshoot and undershoot on the pulse, the 2601B-PULSE System SourceMeter features a control loop system that bypasses the need to adjust for load changes for up to 3 μH manually.


The new SMU's pulse output performance

The new SMU's pulse output performance. Image used courtesy of Tektronix

That control loop system also safeguards the current pulse from overshooting or ringing when utilizing pulses that range from 10 μsec to 500 μsec at a current up to 10 A, which results in fast rise time, accurate pulse output, and high fidelity.


PulseMeter Technology

The secret to eliminating manual pulse output tuning lies in Tektronix’ PulseMeter technology, which uses TSP (Test Script Processor). TSP runs complete test programs from inside the SMU for improved throughput. Tektronix states that for more extensive, multichannel applications, Keithley’s TSPLink technology is deployed along with TSP scripting for high-speed, pulser/SMU-per-pin parallel testing. 


SMU-per-pin parallel testing using TSP and TSP-Link

SMU-per-pin parallel testing using TSP and TSP-Link. Image used courtesy of Tektronix

Do You Work With LiDAR Technology?

If you work with LiDAR technology, what are some pain points you experience in the testing phase? Have you found certain techniques to be more effective than others? Share your experiences in the comments below.