Design of a GaN 1-MHz/48-V-to-1-V/320-A Series-Capacitor Buck Converter

This paper presents the design of a single-stage switched-capacitor converter based on the series-capacitor buck (SCB) topology, suitable for 48-V/MHz VRM. The SCB circuit features reduced voltage stress on switching devices, a device count consistent with multi-phase buck circuits, and the ability to achieve self-balancing of voltage and current. All switching devices utilize GaN transistors, leveraging their advantages such as low parasitic inductance due to lateral structure packaging and high switching speed. An 8-phase SCB prototype was constructed, capable of delivering a full-load output of 320 A. At 1 MHz, the prototype achieves a peak efficiency of 92.07% and a full-load efficiency of 82.06% at 1-V output.