65W GaN Synchronous Current-Mode Class D Rectifier for 6.78MHz Wireless Power Receivers

Current-mode class D, also known as current doubler, is a promising rectifier topology in 6.78 MHz wireless systems, especially in high output current applications. This paper presents an analytical derivation of the input impedance and output voltage for this rectifier. The effect of load variation is also analyzed. A synchronous current-mode class D rectifier is built using GaN FETs and compared to a Schottky diode version. Experimental results demonstrate 69 W output power with 87% total system efficiency and estimated 96% efficiency for the GaN rectifier.