An offset-enhanced active rectifier with delay compensated active diodes for wirelessly powered biomedical implants

This letter presents the design of a 13.56 MHz offset-enhanced full-wave active rectifier, tailored for wirelessly powered biomedical implants. The design incorporates digitally assisted, delay-compensated active diodes and symmetrical bulk biasing in the rectifier core to enhance conduction time, thus improving the voltage conversion ratio (VCR) and power conversion efficiency (PCE). A delay improvement is achieved both in no-load and high-load conditions through an additional comparison path with an offset voltage that is higher than zero. The proposed rectifier is implemented and fabricated in a 180 nm CMOS technology with an area of 0.024 (Formula presented.). The rectifier, tested and measured with inductive links, offers a maximum VCR of 96.4% and a maximum PCE of 89%.