On the Analytical Optimal Load Resistance of RF Energy Rectifier

RF wireless power transfer (WPT) is an essential building block for simultaneous wireless information and power transfer (SWIPT) and wireless powered communication (WPC) systems. It has been shown that the efficiency of RF-DC conversion of a rectifier is dependent on both input power and the load resistance. In this paper, we present a novel analytical solution for the optimal load resistance in terms of DC power on the resistive load for two harvester topologies, namely the series-diode half-wave rectifier and Greinacher voltage doubler. Additionally, closed-form solutions are presented for low input power to obtain intuitive insights. The proposed method models the diode with the equivalent Schottky diode model, taking the parasitic and packaging effects into consideration. The validity of the method is verified by simulations with both continuous sinewave (CW) and multi-sinewave input.