Gate-Drive Power Supply With Decayed Negative Voltage to Solve Crosstalk Problem of GaN Synchronous Buck Converter

Gallium-Nitride (GaN) transistor suits for high switching frequency condition to build high power density converters. However, it suffers from crosstalk problem especially in bridge-structure applications, that is, the fast voltage changing of the switching node causes a positive or negative voltage spike on the gate-source voltage of GaN transistor, which results in false turn-on and gate breakdown of the transistor, respectively. Rather than specially designing the gate driver, this letter proposes an idea of using a gate-drive power supply (GDPS) with decayed negative output to solve the crosstalk problem. With the proposed GDPS, a negative driving voltage is provided when the positive voltage spike appears to avoid false turn-on, and then the negative driving voltage naturally decays to zero before the negative voltage spike appears to avoid gate breakdown. Such a GDPS is realized by a simple forward-flyback topology, and the commercial gate-drive ICs can be cooperated with it conveniently. Experimental results show the effectiveness of the proposed method.