A harmonic-suppressed high-efficiency class-F power amplifier with Elliptic-Function low-pass filter

In this paper, a novel method is developed in order to design a harmonic control circuit block using a compact microstrip low-pass filter (LPF) for a P-HEMT class-F PA. The design procedure is performed using Harmonic-Balance analysis. The key benefit is a novel compact defected Elliptic-Function resonator to design a LPF, which has a wide rejection band. The advantages of the presented method are the attenuation of nth harmonics in AM-AM distortion, high power added-efficiency (PAE) and more linearity in comparison with a conventional class-F PA. The experiment is carried out at 1.8 GHz and shows a maximum PAE about 77% with 40 dBm output power.