An Efficient Reconfigurable RF-DC Converter With Wide Input Power Range for RF Energy Harvesting

This paper presents a reconfigurable radio frequency to direct current (RF-DC) converter operating at 902 MHz frequency designed to efficiently harvest RF signals and convert into useable DC voltages for RF energy harvesting applications. The proposed scheme employs a dual-path, a series (lowpower) path and a parallel (high-power) path, to maintain high power conversion efficiency (PCE) over wide input power range. The dual-path is composed of two identical rectifier blocks utilizing internal threshold voltage cancellation (IVC) technique to efficiently compensate the threshold voltage of the transistors used as rectifying devices. An adaptive control circuit (ACC) consisting of a comparator, an inverter and three switches is used in the proposed scheme. The ACC activates the series path or the parallel path to maximize the harvested power based on the input power range. The proposed scheme is designed and fabricated in a 180 nm complementary metal-oxide semiconductor (CMOS) technology. The measurement results show that PCE of the proposed circuit is above 20% from -18 dBm to -5 dBm, maintaining 13-dB input power range with peak PCE of 33% at -8 dBm for 200 kΩ load resistance. The proposed circuit demonstrates -20.2 dBm sensitivity across 1 MΩ load resistance while producing 1 V output DC voltage.