Class E Amplifier Design Equations for Maximizing the Frequency Utilization of a Device

Dealing with the nonlinear effects of the device´s output capacitance in the design of RF/MW class E amplifiers is a problem that has to be faced by designers, specially when output capacitance exceeds (or is very close) to the design value obtained for satisfying optimum class E switching. This paper makes use of the fact that, the frequency range of utilization of a device may be expanded by reducing duty-cycle to 0.33 and keeping efficiency theoretically 100%. Analytical equations to design class E amplifiers taking into account device nonlinearities for D = 0.33 and for any loaded quality factor are presented and are valid for any possible combination of linear and nonlinear shunt capacitances. This set of equations is obtained from numerical results by means of nonlinear regression curve fitting methods. Experimental verification proving the results is included.