Validating Duty Cycle-Based Repetitive Gate and Drain Transient Overvoltage Specifications for GaN HEMTs

Abstract:
Repetitive transient overvoltage ringing is a switching characteristic that is commonly seen in GaN-based high slew-rate and high frequency applications. Thus, an application driven repetitive transient overvoltage specification is highly desirable. In this work, a 1 percent duty cycle-based overvoltage specification was developed from resistive-load hard switching test biased at 120 percent of maximum drain-source voltage (VDS,Max). To validate the 1 percent duty cycle factor (DCFactor), an unclamped inductive switching (UIS) test circuit featuring in-situ RDS(on) monitoring was imple-mented to emulate the resonance-like overvoltage ringing during drain turn-off transients in applications. The dy-namic RDS(on) shift for voltages under 120 VDS,Peak from UIS is projected to be less than 10 percent after 25 years of continuous operation, which validates the 1 percent DCFactor specification proposed. The 1 percent DCFactor with 7 V gate-source voltage is also applicable to gate overvoltage transients, demonstrating the excellent overvoltage robustness of pGaN gate in GaN HEMTs.