Resistive‐reactive class‐X power amplifier with bandwidth beyond one octave

Abstract

This article presents a resistive‐reactive Class‐X power amplifier (PA) with bandwidth beyond one octave. By introducing resistive component into the second‐harmonic load of Class‐X power amplifier, the impedance design space is expanded. The basic theory of extended Class‐X PA is deduced, including impedance calculation, high‐efficiency design consideration and targeted impedance trace design. An impedance overlapping region between fundamental and second‐harmonic impedances with high drain efficiency is obtained, paving the way for bandwidth enhancement. For validation, the Class‐X and extended Class‐X theory are employed to design a broadband PA with bandwidth of 0.6–2.6 GHz (125%), drain efficiency of 57%–70%, and gain of 10.2–13.2 dB.