Research on Synchronous Rectification Driver Technology of High-Frequency DC-DC Resonant Converter Based on GaN Devices

With the increase of switching frequency to tens of MHz, the synchronous rectification faces many new challenges, among which a significant one is the design of the driver circuit for the synchronous rectification with wide bandgap gallium nitride (GaN) devices. According to the self-resonant driving theory, this paper proposes an in-phase feedback synchronous rectification driver circuit (SRDC) based on GaN devices and the driver chip. In this SRDC, the nonlinear parasitic capacitors are replaced with external capacitors, and the synchronous driving signal is in-phase with the excitation source. The new scheme can provide precise driving timing, stable driving amplitude and flexible phase-shifting characteristics for the synchronous rectification of a high-frequency DC-DC resonant converter (HFDRC) based on GaN devices. In this paper, a detailed parameter design method is introduced by analyzing the characteristics of the feedback network. The feasibility and effectiveness of the proposed SRDC are verified on a 20 MHz prototype with 18 V input and 5 V / 2 A output.