Load impedance perturbation formulas for class-E power amplifiers

Abstract

This paper considers how a class-E amplifier behaves when the load deviates from its nominal impedance. The Kirchhoff’s law and Fourier series formulate the circuit into three simultaneous equations. These equations are decomposed into zeroth- and first-order terms to apply the perturbation technique. The zeroth-order solutions meet the zero-voltage and zero-current switching conditions. The first-order formulas express the DC current consumption, RF output amplitude and phase, equivalent output impedance, and periodic turn-on power dissipation in terms of the load resistance and reactance deviations.