Characterisation of Wide-Bandgap Semiconductors in Double Pulse Testing Using Optically Isolated Probes

Abstract:
As the utilization of wide-bandgab devices in power electronic systems continues to improve power density and efficiency, the knowledge of switching behaviour is crucial for optimized design of the driver circuit as well as module integrated parameter design. To address effects like inter-chip oscillations or parasitic turn-on events (PTO), measurements on the low-side (LS) switch are no longer sufficient. Due to fast switching events, measurements on high-side (HS) potential suffer from high common-mode (cm) stress, which requires devices with high common-mode rejection ratio (CMRR). In order to perform highprecision differential-mode (dm) measurements with high bandwith and low noise distortion for instance on HS-switch gate, high voltage optically isolated probes provide promising features for semiconductor characterisation. This paper provides a detailed application-specific selection of suitable measurement devices, based on datasheet evaluation and hardware verification considering electrical and thermal behaviour of the measurement devices, in order to assemble an optimized double pulse test setup for wide-bandgap devices.