A 20MHz isolated synchronous rectification DC-DC converter based on GaN HEMT

In this paper, an isolated synchronous rectification DC-DC converter based on GaN HEMT is proposed, which can achieve soft-switching characteristics and reduce the conduction loss of the rectifier. In conventional rectifier converter, fast-recovery schottky diodes are used for resonant rectification, and the diode forward voltage drop results in larger diode conduction losses, which causes the power converter to be less efficient. To solve this problem, the proposed topology, whose rectifier diode is replaced by a synchronous switch, adopts synchronous rectification, which helps to improve the efficiency of power converters. Meanwhile, the transformers with magnetic core are also replaced by coreless planar transformers to reduce the volume. Thus, the system efficiency and power density can be improved. To achieve soft switching and reduce switching losses, the driving circuit of the rectifier circuit is optimized and the detailed design method of the proposed converter is analyzed. In tens of megahertz, the GaN HEMTs are adopted to reduce the driving loss, switching loss and conduction loss. A 20MHz prototype based on the proposed topology is designed in this paper. The experimental results verify the feasibility of the proposed converter and corresponding design method.