A 402 MHz and 1.73-VCE Resonance Regulating Rectifier With On-Chip Antennas for Bioimplants

In this paper, a wireless power transfer (WPT) system composed of a voltage-mode fully integrated resonance regulating rectifier (IR${{}^{3}}$) and an on-chip antenna running at 402 MHz has been designed for bioimplants in deep tissue. The proposed IR${{}^{3}}$, including a 200 pF decoupling capacitor, is implemented in a 0.22 mm${{}^{2}}$ active area in the 180-nm CMOS process. A charging duration based regulation compensation circuit offers a low ripple factor of 0.3% at a 1.8 V output voltage and a high voltage conversion efficiency (VCE) of 1.73 to overcome the low inductive coupling coefficient (under 0.01) due to the deep implant scenario. And a clock gating VCDL-based on-&-off delay compensation scheme is proposed to compensate for the phase error of the IR${{}^{3}}$. Performing rectification and regulation simultaneously in a single stage, the IR${{}^{3}}$ effectively enhances power conversion efficiency. The whole system achieves a power conversion efficiency (PCE) of 65% with a 1.5 mW load. In addition, digital control-based compensation circuits also improve its transient response performance, the 1% setting time is only 6.9 $\mu$s when the load changes from 65 $\mu$W to 1.5 mW.