Exact Analysis of Class DE Amplifier with FM and PWM Control

SUMMARY The control of class DE amplifier is an important problem since its switching operations do not satisfy class E switching conditions when the load resistance varies from the initial designed values. Therefore,several of control schemes of class DE amplifier were proposed. However,the changes of the output voltage and the power conversion efficiency by using these controls can be measured only experimentally and thus,they cannot be found theoretically. In this paper,an exact analysis of class DE amplifier with FM and PWM control schemes is presented. From the analysis,we can theoretically derive the output voltage,the power conversion efficiency and so on. Moreover,the frequency and the duty ratio to keep the constant output voltage can be found when the load resistance or the input voltage varies. We indicate that the theoretical predictions are similar to the experimental results quantitatively. The measured efficiency is over 94% with 1.0 MHz and 1.8 W output.