A 434MHz Dual-Mode Power Harvesting System with an On-Chip Coil in 180nm CMOS SOI for mm-Sized Implants
In this paper, we present a mm-sized dual-mode power harvesting system for biomedical implants that can adaptively set the power delivery mode depending on the received RF power level and the required power by the load. The system is fabricated in 180-nm SOI CMOS technology and includes a two-turn on-chip coil. The total area of the fabricated chip is 2.56 mm². A 2 cm×2 cm loop is used to transmit RF power to the fabricated chip through 10 mm of air at 434 MHz. Measurement results show that the designed power harvesting system can achieve a wireless link efficiency of -21.7 dB and a FOM value of 165.1. Keeping the transmitted RF power below 24 dBm, the system can provide a 1.08 V dc voltage for resistive loads larger than 20 KΩ continuously over time. When the transmitted power level is not enough for continuous power delivery, the power harvesting system operates in the duty-cycled mode. In this mode, the system can drive a 1 KΩ load when the transmitted power level is 15 dBm.