A Novel All-Passive Resonant Gate for LLC DCX Synchronous Rectification

The drive losses of synchronous rectifier (SR) mosfets become significant factor limiting the efficiency of high-frequency, low-voltage, and high-current output LLC dc transformer (LLC DCX) in data center power supply applications. The resonant gate driver (RGD) can reduce drive losses, but both semiconductor devices and external power supply are required in the current RGDs, which results in more losses and footprint. An all-passive resonant gate driver (APRGD) is proposed in this letter, which consists only passive components, including inductances, capacitances, and transformer windings. The operation principle and parameter optimization method of the proposed APRGD are illustrated in detail, which is then verified by experiments. The peak efficiency of the prototype is improved by 0.83% after using APRGD, and SR drive losses are reduced by 93.4%. In addition, the footprint of APRGD is similar to that of conventional drive ICs. The proposed APRGD has advantages in efficiency and power density compared to current RGDs.