27.5 A Wireless Power Transfer System with Up-to-27.9% Efficiency Improvement under Coupling Coefficient Ranging from 0.1 to 0.39 Based on Phase-Shift/Time-Constant Detection and Hybrid Transmission Power Control

Wireless power transfer (WPT) is a convenient way to power the wearable/portable devices with water/dusty-proof requirement. The end-to-end (E2E) efficiency $\eta_{E2E}$ is a key specification of WPT system. A compact and efficient solution for WPT receiver (RX) is using the reconfigurable resonant-regulated $(\mathrm{R}^{3})$ rectifier, which regulating the output through configuring the rectifier between charging (1X) and discharging (0X) modes [1]. Under light-load conditions, the 0X mode occupies most of time at RX, reducing the $\eta_{E2E}$ seriously if the transmission power of transmitter (TX) is fixed.