A 3.2 V –15 dBm Adaptive Threshold-Voltage Compensated RF Energy Harvester in 130 nm CMOS

This paper presents an adaptive RF-DC power converter designed to efficiently convert RF signals to DC voltages utilizing auxiliary transistors to control the threshold voltage of the transistors in the main rectifier chain dynamically. The proposed circuit passively reduces the threshold voltage of the forward-biased transistors to increase the harvested power and the output voltage and increases the threshold voltage of the reverse-biased transistors to reduce the leakage current to prevent the loss of previously stored energy. A 12-stage adaptive threshold-compensated rectifier is designed and implemented in IBM´s 0.13 μm CMOS technology. The proposed rectifier exhibits measured maximum power conversion efficiency (PCE) of 32% at -15 dBm (32 μW) of input power while delivering 3.2 V to a 1 M Ω load. At a remarkably low input power of -20.5 dBm (8.9 μW) for a 1 M Ω load, the rectifier produces an output voltage of 1 V.