High-Power and High-Efficiency RF Rectifiers Using Series and Parallel Power-Dividing Networks and Their Applications to Wirelessly Powered Devices

Abstract

The zero-bias and full-wave bridge rectifiers with high RF-to-dc conversion efficiency at high operating power are demonstrated. To overcome the low breakdown voltage limit of silicon-based Schottky diodes, the power-dividing networks are employed to couple the high-input RF power into four differential-type bridge diodes. Transformer-based one-to-four series and parallel power-dividing networks are proposed, and their equivalent circuits are established. To enhance the coupling mechanism of the transformer, the defected ground structures are adopted in the coupled-line sections of power dividing networks. The critical design parameters of power-dividing networks are examined, including the input impedance, the self-resonant frequency, the power loss factor, the phase and amplitude imbalances of differential signal, and the voltage and current on output ports. The bridge rectifiers using the series and parallel power-dividing networks are developed to withstand up to 41-dBm input power before reaching the breakdown limit of Schottky diode, and the RF-to-dc conversion efficiency is 62% for series power-dividing networks and is 76% for parallel power-dividing networks at the operating frequency of 920 MHz and load resistance of 10 Ω. The wireless charging system for a smartphone is established to experimentally validate the application of the high-power and high-efficiency RF rectifiers.