Low-loss rectifier for RF powering of implantable biosensing devices

The biochips are considered as one of the promising concepts for in-vivo or in-vitro characterizing or quantifying of biomolecules. The inductive powering can not only maintain the continuous wireless power from the external source for long term operation of implantable biochip to reduce the risk from the battery leakage or skin infection from the connecting wires, but also establish a wireless communication system between the biochip and the external device. A high-efficiency rectifier unit is needed in inductive-power transfer system to convert the received energy into a usable DC voltage. In this paper, a high power-conversion-efficiency differential inductor based class-E type zero-voltage-switching structure is presented to replace the low efficiency conventional full-wave bridge rectifier. The proposed rectifier unit is designed using 0.5-μm standard CMOS process. Simulation results show that the proposed differential rectifier circuit can achieve more than 92% power-conversion-efficiency for an input AC source of 7 MHz frequency with signal amplitude of 2 V (peak).