A 13.56MHz Active Rectifier with Digitally-Assisted and Delay Compensated Comparators for Biomedical Implantable Devices

This paper presents the design of a 13.56 MHz full-wave active rectifier that utilizes digitally-assisted and delay compensated comparators for wirelessly powered biomedical implants. The proposed design employs delay compensation and digital assistance techniques to maximize the conduction time, resulting in improved voltage conversion ratio (VCR) and power conversion efficiency (PCE). The comparator speed is enhanced using an added latched structure. Also, a dynamic and symmetrical bulk biasing structure is employed in the rectifier core. The proposed rectifier design is implemented and fabricated using a 180nm CMOS process, with a chip area of 0.036mm(2). Experimental measurements are carried out using inductive links resonating at 13.56 MHz, and the proposed rectifier design achieves a maximum VCR of 93% and PCE of 80.8% over a wide input voltage range from 1.5V to 4V. These results demonstrate the effectiveness of the proposed design in achieving efficient power transfer for biomedical implants.