This paper investigates the design curves of the class DE amplifier with the nonlinear shunt capacitances for any output Q and any grading coefficient m of the diode junction in the MOSFET. The design curves are derived by the numerical calculation using Spice. The results of this paper have two important meanings. Firstly, it is clarified that the nonlinearities of the shunt capacitances affect the design curves of the class DE amplifier, especially, for low output Q. Moreover, the supply voltage is a quite important parameter to design the class DE amplifier with the nonlinear shunt capacitances. Secondly, it is also clarified that the numerical design tool using Spice, which is proposed by authors, can be applied to the derivation of the design curves. This shows the possibility of the algorithm to be a powerful tool for the analysis of the class E switching circuits. The waveforms from Spice simulations denote the validity of the design curves.

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.