Enhancing Efficiency and Linearity of Continuous Class-F₃Power Amplifier with Peak-Clipped Current Waveform

Conventional continuous Class-F3 (CF3) power amplifiers (PAs) require designers to provide quasi-infinite third-harmonic load impedances to intrinsic transistors, which is not always feasible in practical design. The conduction-angle-manipulated (CAM) waveform was used in CF3 PAs to remove the condition of infinite third-harmonic load impedance. But the efficiency is significantly degraded in CAM-CF3 PA. In this article, a peak-clipped current (PCC) waveform is proposed for CF3 PA with noninfinite third-harmonic load impedance and enhanced efficiency and gain linearity. The proposed PCC waveform can be intrinsically generated by an overdriven transistor without relying on complex hardware overheads. The advantages of the proposed PCC-CF3 mode are analyzed by comparing it with the CAM-CF3 mode, and the design methodology of PCC-CF3 PA is provided. Finally, a prototype of PCC-CF3 PA is implemented. The experimental results show that the output powers of 41.6-42 dBm, power-added efficiencies (PAEs) of 72%-74%, and gain compressions of below 2.6 dB are achieved over the frequency range from 1.6 to 1.8 GHz. The proposed PCC-CF3 PA achieves high efficiency and excellent gain linearity, simultaneously.