Computation of Dynamic Rds(ON) for WBG Devices Using Mathematical Modelling on Oscilloscope

Dynamic Rds(ON) is an important parameter which decides the performance of a MOSFET including its efficiency. Dynamic Rds(ON) is due to charge trapping phenomenon in complex semiconductor structures. However, measuring Rds(ON) under dynamic conditions poses significant challenges at high drain to source voltages. The latter problem is alleviated by using clamping circuit. But this invasive method brings its own limitations. The paper discusses the problems with measuring dynamic Rds(ON) using oscilloscope measurement system. This paper delineates novel way of modelling mathematically the switching voltage with help of high sample rate acquisition system like oscilloscope. Our methodology involves capturing the drain-source voltage (Vds) using two high voltage differential probes at different vertical resolutions during a double pulse test. By combining these waveforms, we reconstruct a high-resolution Vds waveform, enabling precise computation of dynamic Rds(ON). This methodology does not require additional hardware. The paper correlates result from novel software method and clamping circuits.