Noise Immune Cascaded Gate Driver Solution for Driving High Speed GaN Power Devices

Abstract

GaN HEMTs permit fast switching, leading to high dV/dt being generated across them. The Common Mode (CM) noise associated with the dV/dt propagates through the gate drivers’ isolation barrier capacitance. Due impedance mismatch between the PWM signal line and return, CM to Differential Mode (DM) noise transformation occurs and distorts the PWM signal at the input of gate driver. This paper investigates the impact of high dV/dt induced noise on gate drive performance in GaN systems. Firstly, noise propagation paths and CM to DM noise transformation are analyzed, followed by simulation and Double Pulse Test (DPT) on hardware. The results show that noise distortion causes mis-triggering of the switches. Further, it is proposed that a cascaded stage comprising power supply and gate driver can suppress the noise by increasing the noise path impedance. The proposed method is verified on hardware with turn-off and turn-on dV/dt equal to 88 V/ns and 62 V/ns respectively at 400 V without mis-triggering.