Impact of Negative Turn-Off Voltage On Turn-On Losses in GaN E-HEMTs

Abstract:
Investigating the switching loss dependency of 650 V GaN E-HEMT on turn-off gate voltage, a difference of up to −20% could be identified when lowering the turn-off voltage from 0 V to −2 V. This loss reduction was primarily due to a decrease in turn-on losses, not turn-off losses. To further investigate this effect, a system to provide both positive and negative isolated gate voltages with small increments for both high- and low-side switches has been developed for a double pulse test (DPT) setup and integrated into an automatic control. After measuring losses for low turn-off voltages, the likely cause for this loss reduction is identified, modeled and measured.