Crosstalk Mitigation and Switching Speed Enhancement of GaN HEMT with Adaptive Gate Resistance under Wide Temperature Variation

The enhancement-mode gallium nitride (GaN) high-electron-mobility transistor (HEMT) offers faster switching speed but introduces large dv/dt, which causes crosstalk issues and further raises the risk of false turn-on. Traditional gate drivers address this by increasing the gate resistance to reduce switching speed, but this approach also increases switching loss, especially at high temperature because GaN HEMT’s transconductance decreases with increase of temperature. To resolve this issue, this paper proposes a gate driver circuit featuring adaptive gate resistance under different temperatures. By incorporating a negative temperature coefficient (NTC) resistor, the gate resistance decreases as temperature rises. As a result, GaN devices can switch faster at a high temperature, thereby reducing switching losses. This paper establishes a circuit-level simulation of the turn-on process to predict the crosstalk voltage under various load conditions, ambient temperatures, and gate resistances. Furthermore, it identifies the minimum gate resistance under each condition, thereby providing theoretical guidance for the selection of NTC resistors. Compared with the traditional gate driver, the proposed method improves the switching speed by 52 % from the turn-on time of 45.4 ns to 22.2 ns at 85 °C through the adaptive gate resistance and maintains the same maximum crosstalk voltage under a wide temperature and load current range.