Analysis of dynamic frequency response of class E amplifier

A dynamic response of the output voltage to the input supply voltage VDD of a class E amplifier is derived with modeling the circuit by a low-frequency model and a high-frequency model. If the perturbation frequency is much lower than the switching frequency, the state-space averaging model of the class E amplifier can be approximated as a single-pole low-pass filter composed of the choke inductance LRFC and the parallel combination of the switch resistance and the shunt capacitor resistance. The analysis in this paper is based on the steady-state behavior outside the designed conditions given in [2]. Hence, the derivation is applicable even if the class E amplifier is operated in off-tuned conditions. The analytical results for the frequency response of a 1 MHz class E amplifier matched well with Pspice simulations at the perturbation frequency less than 100 kHz.