Design of a class-F power amplifier with expanding bandwidth

This paper presents a method to expand the bandwidth of conventional class-F power amplifier. Analysis indicates that small characteristic impedance of quarter-wave shorted-circuit transmission line in the harmonic control network is beneficial for PA design, as the second harmonic impedance varies less with frequency variation. A 10W GaN packaged transistor is used to verify the proposed method. The measured results show that the PA exhibits a good performance at the center frequency 2.6 GHz with 74.37% drain efficiency, 40.82 dBm output power and 11.82 dB gain. Besides, the PA maintains more than 60% drain efficiency over the bandwidth of 250 MHz.