Microwave class-E power amplifiers

This paper reviews circuit architectures and demonstrated class-E power amplifiers in the UHF and microwave frequency range. Scaling class-E soft-switching operation to high frequencies presents a number of challenges, particularly in the control of parasitic reactances of the device and the circuit. Different approaches have been taken, from using parasitics of lumped elements to provide the correct fundamental and harmonic impedances in the UHF range, to transmission-line implementations at frequencies above 10GHz.