Analysis on Parasitic Capacitance to Prevent False Turn-on in GaN HEMT

Abstract

Driving power devices such as GaN HEMTs at high-frequency is one of the successful solutions to miniaturize the magnetic components of circuits. On the other hand, GaN HEMTs have drawbacks in high-speed switching. For example, in a full-bridge inverter configuration, a fast turn-on of one power device can cause a false turn-on of the complementary power device. Therefore, the GaN HEMT might be destroyed by the overcurrent and transient heat caused by the short circuit. The most important factor for the false turn-on of GaN HEMTs is its reverse transfer capacitance (Crss), but other parasitic components such as inductances in PCB should be considered to analyze the false turn-on phenomena. In this paper the theoretical analysis of the capacitance components that may cause the false turn-on is conducted. Based on the theoretical analysis, we propose the conditions of the parasitic component of the gate drive circuit to prevent false turn-on.