In this paper, a 13.56-MHz single-comparator active rectifier with auto-calibration achieving improved power conversion efficiency is presented. The proposed single-comparator structure reduces the number of comparators used in an active rectifier. Hence, it minimizes the power loss due to comparators. The auto-calibration mechanism improves circuit stability and makes the circuit insensitive to the process-voltage-temperature variations. The chip is fabricated in the TSMC 0.18-μm CMOS process. The maximum output power is 28.5 mW. The peak power conversion efficiency is 90.1% under a load resistor of 500 Ω and the voltage conversion ratio is 95.1% under a load resistor of 5000 Ω.
