Full Bridge Self-Resonant Synchronous Rectifier for MHz Wireless Power Transfer

Synchronous rectification at several MHz faces a lot of difficulties including signal propagation delay of tens of nanoseconds, the existence of parasitic components, and the significant increase in circuit components and circuit area. These factors limit the wide application of synchronous rectification at the frequency band of MHz. In this work, to partly solve the problem mentioned above, a topology of a full bridge selfresonant synchronous rectifier is proposed. The proposed circuit only contains passive components to maximally reduce the circuit area and generate driving signals through resonance of the passive components to avoid the influence of propagation delay. Experiments are conducted to validate the proposed solution. A full bridge self-resonant synchronous rectifier is built to output 12V/4A with an efficiency of 90.98%. Compared with full bridge rectifier made with the state-of-the-art Schottky Diodes (RBR5LAM40 from ROHM CO., LTD) working under the same conditions, the proposed circuit can reduce the rectification losses by 31.83%.