A new synchronous rectifier using bipolar transistor driven by current transformer

A new synchronous rectifier (SR) unit is proposed. SR has low offset voltage, which improves the efficiency oflow-voltage power supplies. The SR consists of a bipolar junction transistor (BJT) with a low on-resistance and a current transformer (CT). It is turned on by the free-wheeling current due to positive feedback through the CT. This unit needs no extra drive-circuit for BJT. Analysis and practical design considerations for the SR are presented. The lower offset voltage and higher conversion efficiency are obtained experimentally, and the proposed SR is compared with the case of Schottky diode for a 2 V power supply.<
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