High efficiency class-F power amplifier integrated with microstrip asymmetric lowpass filter

In this paper, a novel approach is presented to design a class-F power amplifier (PA) integrated with microstrip asymmetric lowpass filter (LPF). Use of an asymmetric LPF with very good specifications and nonreciprocal frequency response, in the case of a PA, which input and output ports are fixed, can improve the PA characteristics, significantly. The results of this structure is accessing to a high output power and the suppressed unwanted harmonics, which can guarantee a high power added efficiency (PAE) in comparison to the conventional class-F PA. The advantages of this method show the attenuation of nth harmonics, high output power with low DC voltage source, high PAE and good linearity. Experiments have been carried out at 1.8 GHz and showed a maximum PAE value of nearby 75% with about 27.2 dBm output power, under 19 dBm corresponding input power.