Effects of the collector current fall time on the class E tuned power amplifier

Presents the equations governing the operation of the amplifier when the collector current fall time during the on-to-off transition of the transistor is an appreciable fraction of the signal period. A current-source model of the transistor with a linearly decreasing collector current during the fall time is used. The following basic amplifier parameters are determined: the waveforms of the collector current, the collector-to-emitter voltage, the instantaneous power dissipated in the transistor, the optimum values of the load-network components, the output power, the power-output capability, and the collector efficiency. The decrease of the collector efficiency is e.g. 10 percent at 60° fall time. Experimental results are also given. The author shows the behavior of the class E amplifier at higher operating frequencies and provides more accurate circuit design procedure.