High-Frequency Self-Driven Push-Pull Class e Rectifier using Capacitive Voltage Divider

This paper presents a high-frequency self-driven push-pull class E resonant rectifier for a wireless power transfer (WPT) system using an opposite drain-source voltage (VDS) capacitive divider. A self-synchronized rectifier allows us to improve the efficiency of the WPT system by replacing diodes with the active devices such as MOSFETs. However, in the high-frequency operation above MHz frequency, it is very challenging to generate the precise gate signal from the transmitting side for the synchronous rectifier due to the propagation delay of the driver circuits. In order to address this issue, we propose the self-driven synchronous push-pull rectifier without any gate driver. The opposite VDS capacitive dividers synchronize the two GaN-FET switches. Even though the drain-source voltage is higher than 400 V, the voltage is divided down below 5 V using the capacitive divider. The capacitive voltage divider also works as the resonant component for the class E rectifier. The proposed push-pull rectifier was demonstrated by using the RF amplifier as a high-frequency current source at 13.56 MHz. The AC-to-DC power conversion efficiency of the proposed rectifier was 97.26% at the output powe of 541 W and maintained 96 - 97% efficiency under the input current variance and load variance condition.