This paper proposes an improved current driven synchronous rectifier with saturable current transformer and dynamic gate voltage control feature for LLC resonant converter efficiency improvement. A model of saturable current transformer is proposed. Compared with other voltage driven and current-driven synchronous rectifier, this current driven synchronous rectifier has several outstanding characteristics. This synchronous rectifier is completely self-contained. It needs no external signal or power supply. It is also insensitive to parasitic inductance. Inherent dynamic gate voltage control reduces gate loss in the MOSFET by saturable current transformer. A 300W 400V-12V converter is built to demonstrate the advantages of the proposed current driven synchronous rectifier. High efficiency at 98% can be achieved. There is more than 4% efficiency improvement compared with schottky diode.published_or_final_versio
