Class C-E high-efficiency tuned power amplifier

Abstract

A numerical analysis of a Class C-E tuned power amplifier is presented, along with a design procedure and experimental results. The efficiency and the maximum operating frequency of the amplifier are intermediate between those of the Class C and E amplifiers. The collector efficiency of the Class C amplifier is about 70%, whereas that of the Class E amplifier is about 96%. The maximum operating frequency of the optimum-efficiency Class E amplifier is, however, limited by the transistor output capacitance. The operating frequency of the Class C amplifier can be at least 16 times higher than that of the optimum-efficiency Class E amplifier at the same output power, DC supply voltage, and transistor output capacitance. The Class C, E, and C-E amplifiers can be obtained with the same circuit topology. The class of operation depends on the values of the load-network components. The tradeoff between the efficiency and the maximum operating frequency is evaluated for all three classes, using nonlinear time-domain simulation. The experimental and theoretical results are in good agreement.