A 40.68-MHz Active Rectifier Using an Inverter-Based Conduction-Time Generator for Wirelessly Powered Implantable Medical Devices

This brief presents a 40.68-MHz active rectifier with a near-zero-quiescent-current inverter-based conduction-time generator for wirelessly powered implantable devices. By using the proposed scheme, the rectifier achieves near-optimum switching operation with negligible turn-on and -off delays and thus high power conversion efficiency even at very high frequency such as 40.68 MHz. The active rectifier was fabricated in a standard 0.18
$\mu \text{m}$
CMOS process. With a 500-
${\Omega }$
load resistor, the measured power conversion efficiency is higher than 87% through the whole input range of 1.2 V to 1.8 V, and a peak efficiency of 93.3% is achieved with 1.2 V input amplitude.