Design of Class E power amplifier with nonlinear parasitic output capacitance

The Class E amplifier exploits the output shunt capacitor for charge-storing during the operation cycle. The amplifier works even with a nonlinear output capacitor, but the required component values are different from the values resulting with the linear capacitor. In this paper the equations and component values are solved for the first time for a Class E amplifier having a nonlinear output capacitor with hyperabrupt junction voltage-capacitance characteristics. A hyperabrupt junction capacitor is present especially at the drain-to-bulk junction of practical MOS devices. The results of the analysis are presented in plots providing initial component values for MOS Class E power amplifier design. The procedure is validated with a design example of a single-stage 900 MHz MOS power amplifier operating from a 2-V supply voltage.