Single-stage dual-output AC-DC converter for wireless power transmission

Wireless power transmission (WPT) system is widely used in implantable biomedical applications. Conventional power management unit (PMU) in the secondary side normally consists of rectifier and DC-DC converters in series, which shows low power conversion efficiency (PCE). In this work, we propose a single-stage AC-DC converter with dual regulated-outputs, combining output regulation with full-wave active rectifier, which not only improves the power efficiency, but also saves silicon area. Also, a new scheme of delay control is designed to eliminate the high-speed and high-precision comparator used in conventional rectifier, thus reduces the power loss significantly. Trough reusing MOS transistors and adjusting the gate voltage swings, 2X and 3X step-up regulated voltages are realized. A 13.56 MHz integrated AC-DC converter that delivers 10mA output power has been implemented in a standard 180nm CMOS process with a small chip area of 0.663mm
²
. Measurement results demonstrate that it can properly operate with a 0.5~1V AC input, directly providing two regulated DC output voltages of 1.7V and 2.75V. Peak PCE of 79% is obtained under the load of 7.1mW. It has the benefits of compactness, high PCE, high voltage conversion ratio (VCR) and flexible outputs. To date, this work is the first to report the single-stage AC-DC converter with regulated multi-outputs for WPT systems.