Multioctave Power Amplifier Based on Extended Resistive-Reactive Continuous Class F Mode

This paper proposes an extended resistive-reactive continuous class F power amplifier (PA) operating mode. It introduces a new free variable based on the conventional continuous class F amplifier theory, which further expands the impedance solution space of the fundamental and second harmonics and increases their overlapping region without sacrificing the drain efficiency of the PA. The calculation and mathematical derivation of the PA operating performance in this mode are given in this paper. To verify the validity of the theory, a 0.7-4 GHz multioctave GaN PA is designed and fabricated, and experimental measurements show that the saturated output power is 39.5-42.5 dBm and the drain efficiency is $55 \%-73 \%$, exhibiting a good agreement with the theory.