Dual‐mode charge pump with second‐harmonic readout for antenna alignment in wireless power transfer system

Abstract

A charge pump is presented by integrating two identical voltage doublers and a modified rat-race coupler to enable its dual-mode operations: radio-frequency (RF)-to-direct current (dc) power conversion and second-harmonic readout. Due to the property of the modified rat-race coupler, it is able to differentially divide incident RF signals for successive voltage doublers' high-efficiency rectification, and couple second harmonics for readout in two highly isolated channels. Output dc voltages are combined in parallel on a single load resistance for more practicality. Experimental validations are demonstrated by both simulation and measurement with a maximum RF-to-dc power conversion efficiency of 71.3% and −14.2 dBm second-harmonic generation with an incident signal power of 19 dBm. This dual-mode charge pump brings a prospect for antenna alignment in the wireless power transfer system by further exploiting second harmonics.