Monolithic Integration of a 400 V GaN Half-Bridge Converter With Output Voltage Regulation

This work presents a 400V monolithically integrated half-bridge buck converter implemented in a 650V GaN-on-SOI technology. It integrates gate drivers, switching logic and power management into a single HV ASIC. A 36 ns comparator and a configurable timer enable use as a ripple-based Constant-On-Time (COT) regulator with 1.4% transient load regulation for a 75% load step. Furthermore, stand-alone operation without external signal generation and reduced external component count is possible. A peak efficiency of 92.0% converting from 400V to 48 V, 95.5% peak efficiency and 15.7Wmm-2 power density are achieved. A zero-voltage detector enables soft-switching by sensing the falling-edge of the switch-node, resulting in up to 5.5% efficiency gain.