6.4 Parallel-Circuit Class E

The theoretical analysis of a switched-mode parallel-circuit Class-E power amplifier using a series filter with the calculation of the voltage and current waveforms and some graphical results was done by V. B. Kozyrev [17, 18]. Let us analyze the parallel-circuit Class-E mode in more detail. The basic circuit of a switched-mode parallel-circuit Class-E power amplifier is shown in Fig. 6.9(a). The load network consists of a finite dc-feed inductor L, a shunt capacitor C, a series L ₀C ₀-resonant circuit tuned to the fundamental frequency, and a load resistor R. In this case, the switch sees a parallel connection of the load resistor R and parallel LC circuit at the fundamental frequency as shown in Fig. 6.9(b) where also the real and imaginary collector fundamental-frequency current components I _x and I _R and real collector fundamental-frequency voltage component V _R are indicated.

For a subharmonic Class-E mode, to compensate for the resulting phase shift provided by the finite dc-feed inductance and shunt capacitance tuned to half of the fundamental frequency, it is required to include an additional series phase-shifting inductance L _x. In the case of a parallel-circuit Class-E load network without series phase-shifting reactance, since the parameter q is unknown, generally it is necessary to solve a system of three equations to define the three unknown parameters q, p, and ?. The two equations are the result of applying the two optimum zero voltage...