A Fully-Integrated CMOS Gate Driver for a GaN-Based Half-Bridge in 48/12 V Bidirectional Automotive Power Conversion

Abstract

Bidirectional DC/DC converters are essential for efficient power distribution in electric vehicles. Gallium nitride (GaN) devices enable high power density as switching elements, but their intrinsic characteristics impose stringent requirements on the reliability of GaN drivers. This article proposes a fully-integrated half-bridge GaN driver, which enables bidirectional power transfer between 12 and 48 V systems. A three-level/bipolar GaN gate driver enhances system reliability under high dv/dt conditions. The integrated charge-sharing bootstrap circuit achieves a compact design and reliable operation of the high-side device. The adaptive dead-time modulation provides an adjustable delay under different load conditions to minimize the dead-time loss. The proposed GaN driver is fabricated in a $0.18~\mu $ m BCD process with a die area of 3.654 mm2. Design considerations in the layout and printed circuit board (PCB) implementation are discussed. Measurement results demonstrate that at a 5 MHz operating frequency, the driver achieves bidirectional conversion between 12 and 48 V. The peak efficiencies are 94.6% for the 18-to-12 V conversion and 94.18% for the 12-to-18 V conversion. Experimental results show that the design can achieve a maximum output power of 22.12 W in buck mode and 22.06 W in boost mode.