Design and Analysis of Class E/F Power Amplifier with Nonlinear Shunt Capacitance at Nonoptimum Operation

This paper presents analytical expressions for the Class-E/F 3 power amplifier with a nonlinear shunt capacitor for satisfying the nonoptimum condition at 50% duty ratio. The design parameters for achieving the nonoptimum condition are expressed as a function of the phase shift and dc supply voltage. The Class-E/F 3 amplifier with nonoptimum condition increases one design degree of freedom compared with the optimum conditions. Because of the increase in the design degree of freedom, one more relationship can be specified as a design specification. The following parameters series reactance, peak switch voltage, output power capability, and maximum operating frequency are presented. Based on analytical results, an example of the Class E/F 3 at operating frequency of 4 MHz is analyzed. The PSpice simulation and measured results agree with the analytical expressions, which show the validity of our analytical expressions at zero-voltage switching.