A Monolithic GaN Active Gate Driver Achieving 71.6% Ringing Reduction Across Various Load Currents Using A Ringing Sensor and Simplified Digital Algorithm

Abstract

The switching node ringing due to parasitic inductances and capacitances in power converters is a major source of electromagnetic interference (EMI) and reliability issues. This paper presents a closed-loop active gate driving scheme in a 400-V monolithic GaN buck converter, which consists of a 2-bit gate driver, a ringing sensor, and an adaptive controller, to reduce ringing without sacrificing power efficiency across various load currents. The 2-bit stop-and-go gate driver suppresses ringing using a pre-defined output current profile and an adaptive, fine-tuned timing determined by the adaptive controller. A ringing sensor monitors the ringing amplitude continuously. Based on the ringing sensor output, the controller uses a fast single variable algorithm to control the gate driver timing across various load currents. Implemented in a 650V monolithic GaN process, the buck converter with the proposed closed-loop adaptive gate driver achieves a ringing reduction of up to 71.6% with 1A to 5A varying load current, while consuming the same transition power loss compared to a benchmark fixed gate driver.