An Area-Efficient Rectifier with Threshold Voltage Cancellation for Intra-Body Power Transfer

In this paper, the feasibility of the intra-body power transfer is verified and an area-efficient rectifier with threshold voltage cancellation for intra-body power transfer is proposed. Through the measurement, the optimum power transmission frequency is determined as 1 MHz. Since the transmission voltage gain is sufficiently high (about 0.3) and nearly constant over a wide range of the load resistance, the intra-body power transfer works well even with the nonlinear and varying input impedance of the rectifier that is placed right after the receiving electrode. The proposed area-efficient rectifier cancels the threshold voltage by using a diode-connected device with a dynamically biased current source. It achieves a considerably smaller area of 65 μm × 30 μm than the area consumed by other designs reported previously. The overall power conversion efficiency (PCE) and voltage conversion ratio (VCR) are also improved. It achieves 84.4% of PCE and 85.6% of VCR with 1-V input voltage and 40-kΩ load.