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.