A 140W 97%-efficiency 4MHz two-phase buck converter with quasi-square-wave ZVS scheme

This paper presents a high-frequency high-efficiency two-phase buck converter with quasi-square-wave (QSW) ZVS scheme for high-voltage automotive applications. A set of auxiliary inductor and capacitor is shared between two-phase sub-converters to realize ZVS for all power FETs and minimize converter switching power loss under high-voltage and high-frequency conditions. The proposed two-phase structure reduces the required current ripple in the auxiliary inductor, thereby reducing the core loss at high switching frequency. The sizes of the main inductor and the output capacitor are also reduced due to the current ripple cancellation in the two-phase converter. With enhancement-mode GaN FETs, simulation results show that the proposed two-phase QSW-ZVS converter can operate at 4 MHz and achieve peak power efficiency of 97% at a full power of 140 W.