A 69.3% Efficiency, 6.78-MHz Wireless Power Delivery System with 0X/1X Regulating Rectifier and Reconfigurable Power Amplifier

In this paper, we present a 6.78-MHz high-efficiency wireless power transfer system with a reconfigurable class-D power amplifier and a 0X/1X regulating rectifier. The proposed reconfigurable power amplifier delivers 0.25X/1X output power by adjusting the power-stage configuration to improve system efficiency. To enhance the receiver efficiency, the proposed 0X/1X regulating rectifier with adaptive offset compensation achieves both voltage rectification and voltage regulation in a single conversion stage. The measurement results demonstrate a 90.1% peak receiver efficiency and a 69.3% peak system efficiency. The system provides the load circuit with 5-V regulated output and 250-mW maximum output power.