Overvoltage Robustness of p-Gate GaN HEMTs in High Frequency Switching up to Megahertz

Stability, Reliability, and Robustness of GaN Power Devices: A Review

“…This test is applied to SP-HEMTs and HD-GITs from different vendors to study the failure boundary and ruggedness. Most devices show a consistent overvoltage failure boundary (i.e., dynamic BV) with the UIS/CIS measurements up to MHz [174].…”

“…To date, three methods have been developed to characterize the overvoltage ruggedness and dynamic BV for GaN HEMTs, i.e., the UIS circuit, the clamped inductive switching (CIS) circuit [170], and the active clamping circuit (ACC) [173], [174]. The schematic and typical waveforms of these three circuits are illustrated in Fig.…”

“…A limitation of UIS and CIS circuits is the difficulty of evaluating the device's overvoltage ruggedness in very high frequency switching. To address this limitation, a softswitching buck converter with an ACC is developed in [173], [174], as shown in Fig. 9(c), which allows for the continuous kilovolt overvoltage switching at a frequency up to 1 MHz.…”

“…When the frequency of overvoltage switching is higher (e.g., >100 kHz), two premature failures have been reported for some SP-HEMTs, leading to failures at the voltage level much lower than the dynamic BV [174]. One failure features a drastic, nearly unrecoverable RDS,ON increase, leading to conduction loss rampup and thermal failure.…”

“…These two premature failure mechanisms are both due to the severe trapping occurred in the GaN HEMT at very high frequency. To screen the devices suffering from these extrinsic failures, highfrequency continuous UIS tests can be used as an effective method [174].…”