Design of a Novel GaN-Based 4-MHz ZVS Active-Clamping Synchronous Buck Converter

In order to overcome the complexity problem in the control circuit of the traditional soft switching power converter, this paper presents a new active clamped synchronous Buck soft switching topology with simple structure and convenient control method. The operating modes and soft switching conditions are analyzed in detail. All switches in this topology can be switched on and off with zero voltage condition, so the switching loss is greatly reduced and it can be applied to a switched mode power supply with MHz working frequency. After Spice simulation analyzing, the way how to stabilize the driving voltage to enhanced GaN transistor is determined. The method deriving the equivalent circuit of small signal model under PWM on/off closed loop control mode is given in detail for the first time. In the end, experimental results proved the feasibility of the proposed topology and the accuracy of the closed-loop control method.