BJT class-F power amplifier near transition frequency

This paper presents the analysis and the design rules of bipolar junction transistor (BJT) class-F power amplifier operating at a frequency comparable with the transition one. Since the impulse of collector current becomes stretched with operation frequency increasing, its spectral content is changed. Thus, the requirements for the amplifier's output network and bias conditions should be corrected compared with the classic low-frequency case in order to achieve high-efficiency class-F operation. Using the simple BJT model, these new requirements were obtained in this paper. The presented results of simulation and experimental verification show the advantages of proposed approach.