A 13.56MHz CMOS rectifier with switched-offset for reversion current control

A 13.56 MHz full-wave active rectifier for wirelessly powered high-current biomedical implants is presented. It employs switched-offset in reducing the comparator delay for reversion current control. The rectifier was fabricated in a standard 0.35 μm CMOS process with an active area of 0.041 mm
²
. The measured power conversion efficiency is better than 83% over a wide ac input range (1.5 to 4 V) and load range (5k to 500 Ω), and reaches up to 90% at 3.5 V and 1.8 kΩ.