A Highly-Efficient RF Energy Harvester Using Passively-Produced Adaptive Threshold Voltage Compensation

This article presents a highly-efficient radio frequency energy harvester that utilizes an extra matching network to produce a passively-amplified adaptive compensation voltage. The compensation voltage produced on the gate of the transistors reduces the transistors’ conduction loss by increasing the gate-source voltage when transistors are on and reduces the leakage current by producing a negative gate-source voltage when the transistors are off. This is the first work that produces an adaptive compensation voltage without using active components, resulting in a significantly higher conversion efficiency if passive components of high quality are utilized. The mathematical derivations show that the forward conduction loss and the leakage current of the transistors are minimized by utilizing the proposed technique, increasing the overall efficiency. The proposed rectifier is fabricated in a TSMC 130 nm standard CMOS process, and measurement results and simulation results are in good agreement. Measurement results show that the rectifier achieves the maximum efficiency of 61% and 63.4% for battery load of 1.2 V and 1.5 V, respectively, which is at least 20 % larger than the efficiency of the conventional Dickson’s rectifiers.