Switchmode RF and Microwave Power Amplifiers, 2nd Edition

Chapter 3

Class-F Power Amplifiers

Introduction

Highly efficient operation of the power amplifier can be obtained by applying biharmonic or polyharmonic modes when an additional single-resonant or multi-resonant circuit tuned to the odd harmonics of the fundamental frequency is added into the load network. An infinite number of odd-harmonic resonators results in an idealized Class-F mode with a square voltage waveform and a half-sinusoidal current waveform at the device output terminal. In Class-F power amplifiers analyzed in the frequency domain, the fundamental and harmonic load impedances are optimized by short-circuit termination and open-circuit peaking to control the voltage and current waveforms at the device output in order to obtain ...