Exact Time-Domain Analysis of Class E Power Amplifiers with Quarterwave Transmission Line

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  • Author: Andrei Grebennikov
The switched-mode tuned Class E power amplifiers with a shunt capacitance have found widespread application due to their design simplicity and high efficiency. These power amplifiers are widely used in different frequency ranges and at output power levels ranging from several kilo-watts at low RF frequencies up to about one watt at microwaves. In the Class E power amplifier, the transistor operates as an on-to-off switch and the shapes of the current and voltage waveforms pro-vide a condition where the high current and high voltage do not overlap simultaneously. This mini-mizes the power dissipation and maximizes the power amplifier efficiency. The possibility of in-creasing the efficiency of the single-ended power amplifier by mistuning the output matching cir-cuit was found quite a long ago [1]. However, the single-ended switched-mode power amplifier with a shunt capacitance as a Class E power amplifier realizing ideally 100-percent efficiency was first introduced in 1975 [2].