Mihai Albulet

An exact analysis of Class-DE amplifier at any output Q

Previous papers on Class-DE power amplifiers are based on the assumption that the Q factor of the series-tuned circuit is high enough that the load current is sinusoidal. This paper presents a theoretical description of the Class-DE power amplifier in which the assumption of infinite Q is eliminated. Design and performance curves are given and discussed and a comparison with the previous known results, a practical tuning procedure, and practical limitations of the Class-DE circuit are also presented. Such an analysis is useful because low-Q circuits are appropriate for applications in which the harmonic content of the output is not important, e.g., in high-efficiency DC/DC converters, in providing RF energy for heating, for generation of plasmas, arcs, or sparks, for communications jamming, or for input driver to a higher power stage. Experimental results closely agree with the theoretical predictions.

Analysis and design of the Class E frequency multipliers with RF choke

The Class E frequency multiplier has already been analyzed using a method which does not take into account the Q-factor of the series tuned circuit (restricting thus the applicability of the results to the high-Q region), and the switching device ON resistance. The analysis presented here takes into account these important parameters which affect the multiplier performance. Design and performance curves are given and discussed for the case of the RF choke, shunt capacitor, series-tuned configuration. It is seen that the multiplier performance is strongly affected by both of Q-factor and switching device ON resistance. Also, it is shown that the optimum operation of frequency multiplier (that is voltage across switch and its derivative equal to zero when the switch turns ON) is not realizable for low Q values. Laboratory results show an excellent agreement between experimental values and the theoretical predictions. >