Flexible 1.5-GHz Probe Isolation Extension With High CMRR and Robust dv/dt Immunity Empowering Next-Generation WBG Measurement

Advancements in the next-generation wide-bandgap (WBG) power devices, distinguished by higher blocking voltage and faster switching speed, give rise to the advent of ultrahigh d v /d t . These three factors collectively impose demanding performance requirements on future high-performance measurement systems. This article conducts an in-depth exploration of the challenges encountered during the low- and high-side dynamic testing of the next-generation WBG device. Drawing from this examination, the performance requirements for future galvanically isolated testing systems are summarized, i.e., a broad dynamic range extending to medium voltage (MV) levels, a minimum measurement bandwidth of 500 MHz, a common-mode rejection ratio (CMRR) of at least 50 dB at 100 MHz, and a d v /d t immunity exceeding 100 V/ns. To effectively response these objectives, the concept of probe isolation extension (PIE) is introduced, with the aim of providing exceptional galvanic isolation while preserving the high electrical performance of traditional non-isolated testing systems to the greatest extent possible. Building upon the PIE concept, an optics-based physical implementation method, known as optical dock (OD), is presented. The operating principles of the OD are derived, and a detailed analysis is conducted to examine the factors that influence its high-frequency response. Additionally, parameter tuning methods are provided to maximize its bandwidth. These collective efforts have successfully resulted in the development of a high-performance PIE OD, which exhibits outstanding galvanic isolation capability, an ultrahigh bandwidth of 1.53 GHz, a high CMRR of 72 dB at 100 MHz, and robust d v /d t immunity of 1.3 kV/ns. Extensive comparative experiments with the state-of-the-art galvanically isolated probes/systems have demonstrated that by incorporating PIE OD to expand various different non-isolated probes/systems, precise characterization of all high-side dynamic electrical parameters, i.e., v gs , v ds , and i d , for the MV SiC MOSFET can be achieved. This highlights the significant potential of the PIE OD for next-generation WBG and even ultra-WBG applications.