A high efficiency active rectifier with zero current sensing for loosely-coupled wireless power transfer systems

Abstract

This paper presents a full-wave active rectifier with zero current sensing technique for wireless power transfer system. In order to improve the Power Conversion Efficiency (PCE), the four diodes of a passive diode rectifier are replaced by N-type LDMOS to reduce voltage drop and enhance high voltage protection characteristic. Moreover, Zero Current Sensing (ZCS) is proposed to detect reverse leakage current so that gate control signal becomes off before reverse leakage current flows and PCE can be maximized. The proposed rectifier is fabricated using 0.18μm CMOS process and occupies 4 mm2 of area. The maximum simulated PCE of 96.8% at 150-kHz.