Structure-Reconfigurable Power Amplifier (SR-PA) and 0X/1X Regulating Rectifier for Adaptive Power Control in Wireless Power Transfer System

This article presents a 6.78-MHz wireless power transfer system with a structure-reconfigurable power amplifier (SR-PA) and a 0X/1X regulating rectifier. The proposed 0X/1X regulating rectifier with local-loop control achieves voltage rectification and regulation without dc-dc converter usage to improve the receiver efficiency. To further enhance the system efficiency, the proposed SR-PA with global-loop power control adjusts its power-stage structure to realize adaptive power delivery. The transmitter and receiver chips were fabricated in a 0.25-μm CMOS process using 5-V devices, and the resulting system was able to regulate an output voltage of 5 V. The measurement results demonstrated an 11.2% improvement in system efficiency for a light load and a 2.7 times increase in available output power compared with the same system without transmission power control. A measured peak receiver efficiency of 92.9% and a total system efficiency of 71.5% were also demonstrated.