Inaccuracy and Instability: Challenges of SiC MOSFET Transient Measurement Intruded by Probes

SiC MOSFET is increasingly implemented for high frequency and high power density converters. However, due to the breakneck switching speed of the SiC device and the parasitics of measurement probes, accurate and stable measurements of the transient behavior of SiC MOSFET pose unsolved challenges. In this paper, the inaccuracy and instability of SiC MOSFET caused by measurement probes are highlighted. Besides, mathematical models, interaction mechanisms and influence factors of transient measurement SiC MOSFET intruded by probes are proposed. Concerning the measurement inaccuracy, the bandwidth, rise time and propagation delay of probes and oscilloscope are modeled. Concerning the measurement instability, to understand the interaction mechanism between device and probes, impedance-oriented models of device and probes are proposed. From the perspective of small-signal model, the stability of tested SiC MOSFET influenced by the parasitics of probes are comprehensively modeled. Experimental results are presented to verify the proposed models.