Novel High-frequency and High-Efficiency Synchronous Buck Converter with a Small Coupled Inductor

A novel high-frequency and high-efficiency synchronous buck converter with a small coupled inductor is proposed in this paper. The proposed converter introduces a small coupled inductor and a ripple steering branch consisting of an inductor and a capacitor. The coupled inductor current which is bi-directional allows two GaN-MOSFETs to operate with ZVS. Moreover, the output current ripple and output filter requirement are reduced significantly with the ripple steering branch. Thus, both high frequency and efficiency promotion can be achieved. The operating principle and analysis of the proposed converter are introduced. Experimental results based on a 48-W prototype switching at 500kHz are presented to verify the performance of the proposed converter.