Optically Isolated Probes for SiC Double-Pulse Testing: Typical Applications

SiCOptically isolated probe: the best choice for double-pulse testingTypical applications

Introduction: The full text is 589 characters; reading takes about 3 minutes. There is a surprise in the appendix at the end of the article.

As is well known, double-pulse testing is currently the best method for understanding the dynamic parameter characteristics of SiC. The optically isolated probe is also the best choice for measuring VGS. In particular, measuring the high-side VGS presents the greatest challenge.

At present, the Vgs(th) of most SiC MOSFET devices is within 2-3 V; combined with their fast switching speed and high operating voltage, their risk of false turn-on is often higher than that of Si MOSFETs and IGBTs, which requires sufficient attention.

Currently, mainstream optically isolated probes on the market include Tektronix IsoVu, PMK FireFly, LeCroy DL-ISO, Micsig SigOFIT, Cybertek OP6000A, etc. Today we will focus on the one with the highest performance and compatibility among all mainstream optically isolated probes: the PMK FireFly series optically isolated probe manufactured by PMK in Germany.

PMK FireFlyOptically isolated probe

Highest performance is mainly reflected in the following three key specifications:

◆ Highest bandwidth: ≥1.5 GHz

◆ Fastest rise time:

◆ Highest common-mode rejection ratio (CMRR): ≥180 dB

The highest compatibility is mainly reflected in the following two aspects:

◆ Compatible with oscilloscopes of all brands on the market: standard BNC output (works with any oscilloscope)

◆ Compatible with all mainstream standard interfaces on the market: MMCX, MCX, SMA, BNC, etc.

In addition, the PMK FireFly series optically isolated probe also has the following features:

◆ Biomimetic probe form factor: enables convenient measurement in confined spaces

◆Unique 3D probe positioner: 360° flexible adjustment of direction and height, customizable for high-temperature resistance up to 200°C

◆Extensive range of fixtures: enable accurate measurement in various environments and applications, with maximum temperature resistance up to 155°C

Optically isolated probes are mainly used in the following three scenarios:

High-side measurementCROSSTALK

Low-side measurementVGS

High-side measurementID(requires non-inductive coaxial shunt)

In addition, we also conducted comparative evaluation experiments on several mainstream optically isolated probes on the market, hoping to help engineers select suitable optically isolated probes. Appendix: URL of the raw data for the optically isolated probe comparative evaluation experiments:  

http://www.probemart.com/portal/test/show.html?id=42