A Monolithic GaN Half-Bridge With High-Speed Auto-Zero Comparator and Bidirectional Level Shifting

Abstract

This paper presents a monolithically integrated GaN half-bridge with all auxiliary high-speed and high-voltage circuits required for resonant converter applications. It integrates two 650 V power transistors and slew rate limiting gate drivers with 7.2 ns delay, achieving a peak 65% <inline-formula><tex-math notation="LaTeX">$dV/dt$</tex-math></inline-formula> reduction with minimal additional delay by using a non-linear output impedance. The integrated level shifters enable bidirectional level shifting between high- and low-side domains with common-mode transient immunity values above 100 V ns<inline-formula><tex-math notation="LaTeX">$^{-1}$</tex-math></inline-formula>. An integrated auto-zero comparator with 23 ns delay and 400 <inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>V offset enables low-noise, high-precision current control with an integrated sense-FET. High-speed reverse conduction and de-saturation detection are enabled by a shared drain-voltage limiter circuit. The components are verified in a 3505 V resonant buck converter system, requiring only a purely digital external controller, and fabricated in a 650 V GaN-on-Silicon-on-Insulator technology.