A class E synchronous rectifier based on an E-pHEMT device for wireless powering applications

In this paper, the design of a class E synchronous rectifier, working in the 900 MHz frequency band and based on an Enhancement-mode Pseudomorphic High Electron Mobility Transistor (E-PHEMT), is proposed. Thanks to its small on-state resistance and its slightly positive threshold voltage, this type of device may offer an excellent performance when operated as a switch without biasing its gate terminal. After properly extracting its model parameters, the optimum drain terminations, required for guaranteeing zero-voltage and zero-derivative switching conditions (ZVS and ZDS), were estimated. Taking advantage of the time-reversal duality, a lumped-element class E amplifier was first designed, to then introduce a drain-to-gate feedback and operate it in the desired synchronous rectifying mode. An efficiency peak of 83% has been measured at 17 dBm, staying above 70% for a 14 dB input power range, a distinguishing characteristic when compared to Schottky diode based alternatives. The verified AM-AM conversion linearity would also allow using the rectifier for the efficient extraction of a time-varying excitation envelope without significant distortion.