A High-Efficiency 6.78-MHz Full Active Rectifier With Adaptive Time Delay Control for Wireless Power Transmission

摘要

This paper presents a full active rectifier consisting of GaN devices and a CMOS controller designed for wireless power transmission in high-power consumer devices. An adaptive time delay control circuit is developed to maximize the conduction interval of the GaN switch, which can significantly reduce the power loss caused by the forward voltage imposed by the diode. The proposed control algorithm also eliminates the reverse leakage current of the rectifier, and thus further improves its power transfer efficiency. The controller implemented based on a high-voltage 0.18-μm CMOS process and the power stage consisting of four GaN transistors are assembled on the same printed circuit board (PCB) board. The proposed rectifier provides a maximum output current of 3 A at 5 V, with a 6.78-MHz ac input voltage. Its peak power transfer efficiency is 91.8%.