A power efficient buck‐boost converter by reusing the coil inductor for wireless bio‐implants

Summary In this paper, a buck‐boost converter circuit for wireless power transfer via inductive links in bio‐implantable systems is presented. The idea is based on reusing the power receiver coil to design a regulator. This method employs five switches to utilize the coil inductor in a frequency other than the power‐receiving signal frequency. Reusing the coil inductor decreases the on‐chip regulator area and makes it suitable for bio‐implants. Furthermore, in the proposed technique, the regulator efficiency becomes almost independent of the coil receiving voltage amplitude. The proposed concept is employed in a buck‐boost regulator, and simulation results are provided. For a 10 MHz received signal with the amplitude variation within 3 ~ 6 V and with the converter switching rate of 200 kHz, the achieved maximum efficiency is 78%. The proposed regulator can also deliver 10 μA to 4 mA to its load while its output voltage varies from 0.6 to 2.3 V. Simulations of the proposed converter are performed in Cadence‐Spectre using TSMC 0.18 μm CMOS technology. Copyright © 2017 John Wiley & Sons, Ltd. In this paper, a buck‐boost converter for power transfer via inductive links in bio‐implantable systems is presented. There is a large inductor in the structure of the buck‐boost converters. Reusing the inherent inductor of the power receiver coil resolves the need for a new large off‐chip inductor in the converter. Furthermore, in the proposed technique, the regulator efficiency becomes almost independent of the coil receiving voltage amplitude, which is a big challenge in wireless power transfer via inductive links. By adding just five switches and a control circuit to the power receiver coil and the rectifier, a very small buck‐boost converter is achieved, which make it suitable for bio‐implant applications.