Gate Drive Circuit for Noninsulating Gate GaN-Transistors Enabling Fast Switching and High-Frequency Operation

Abstract

Increasing requirements for high switching frequency and high power density have driven the development of gallium nitride power transistors. Among them, some GaN transistors feature a noninsulating gate, such as gate injection transistors and Schottky-gate GaN transistors. Driving GaN transistors with a noninsulating gate is challenging, as a high gate current is required for rapid switching transitions, and a low continuous gate current is needed to maintain the device in the on-state and minimize losses. The conventional drive circuit for metal-oxide-semiconductor field-effect transistors and insulated-gate bipolar transistors is not suitable anymore and the RC-type drive circuit recommended by manufacturers suffers from unstable turn-off voltage and inconsistent operation performance depending on the switching frequency and duty cycle. To address these issues, this article proposes an improved drive circuit designed with an active discharge path. This drive circuit can be easily implemented using standard commercially available driver ICs, requiring only one additional auxiliary switch without the need for additional control circuitry. It can drive noninsulating gate GaN transistors in the MHz range without performance degradation, enabling fast switching and ensuring a fixed turn-off voltage independent of operating points and transistor parameters. This feature enhances immunity to false turn-on, reduces losses and design complexity, and makes the circuit particularly suitable for high-frequency industrial applications. The drive circuit configuration and operation principle are introduced and its effectiveness is experimentally verified for two types of noninsulating gate transistors in a buck converter at a switching frequency of 5 and 10 MHz, respectively.