Effects of circuit variations on the class E tuned power amplifier

TLDR

Class‑E tuned power amplifiers are modeled by Fourier‑component equations, and prior work has shown an idealized circuit can achieve 100 % collector efficiency. This study investigates how nonideal components and loads affect the performance of real Class‑E amplifiers. Using the basic equations, the authors analyze how variations in component values and duty cycle—specifically load reactance, shunt capacitance, load resistance, frequency, and duty cycle—alter amplifier behavior, presenting numerical results for each. The amplifier remains tolerant to realistic circuit variations, and with proper output filtering it can operate over nearly an octave bandwidth while losing less than 5 % efficiency.

Abstract

The operation of the class E tuned power amplifier may be described by a set of equations based on Fourier component analysis. Previous publications have derived an optimum operating mode in which the collector efficiency of an idealized circuit is 100 percent. Since real amplifiers are made from nonideal components and are subject to nonideal loads, it is necessary to determine the effects of deviations from the ideal. The effects of variations in component values and duty cycle are determined from the basic equations. Numerical results of variations in load reactance, shunt capacitance, load resistance, frequency, and duty cycle are presented. The amplifier was found to be quite tolerant of reasonable circuit variations. With proper output filtering, the amplifier can be operated over nearly an octave bandwidth with less than a 5 percent reduction in efficiency.