A ZVS CMOS active diode rectifier with voltage-time-conversion delay-locked loop for wireless power transmission

An efficient CMOS active diode rectifier for wireless power transmission using zero-voltage switching (ZVS) technique to suppress reverse current is demonstrated by the proposed voltage-time conversion (VTC) delay-locked loop (DLL) circuit. The proposed VTC DLL achieves synchronization between the switching transistor and AC input without a replica delay circuit that is difficult to realize and vulnerable to the circuit operating conditions conventionally. The proposed circuit is implemented in a standard 0.18μm CMOS process using I/O MOSFETs, which nearly corresponds to 0.35μm technology. The maximum power conversion efficiency of 78% is obtained at 39mW output.