A GaN-Based Buck Converter Resilient to Battery Voltage Fluctuations With 96.3% Peak Efficiency

The voltage fluctuations of 48 V batteries in electric vehicles challenge the robustness of switching converters by disturbing the output voltage during cold-crank and load-dump events. To address this issue, this paper presents a 48 V-to-12 V buck converter employing gallium nitride (GaN) devices to enable high switching frequency (FSW) operation and feedforward control, thereby enhancing line transient performance and stabilizing loop dynamics. However, higher FSW also increases the slew rate at the switching node, imposing stricter noise immunity requirements on circuit operation. To overcome this limitation, a noise-immune sub-nanosecond level shifter (NSLS) is introduced to ensure fast and reliable signal transmission for high-speed operation. In addition, a Miller plateau leakage elimination (MLE) technique mitigates unintended gate coupling induced by high dV/dt, effectively reducing leakage losses. Beyond high-frequency operation, an adaptive P-type ramp generator (APR) facilitates feedforward control by emulating a P-type current mirror, eliminating input-voltage dependency in the control loop. Fabricated using a 0.5-μm GaN process, the proposed converter achieves a peak efficiency of 96.3% while significantly improving transient performance under input-voltage variations.