A high‐efficiency power amplifier by using harmonics control

A harmonics control high‐efficiency power amplifier (PA) is proposed by combining an asymmetrical branch‐line coupler (ABLC) and a shunt transmission line. With the special ports impedance condition, the ABLC realizes impedance transformation as well as shorts even‐harmonics, and the shunt transmission line shorts the third harmonic. Herein, two‐stage couplers not only expand the bandwidth but also enhance the harmonics control. A PA is simulated and fabricated to verify the proposed method. The measured results show that the typical saturated output power is more than 40 dBm, the drain efficiency is 60.3%–81.3%, and the power gain is 10.4–17.9 dB from 1.4 to 2.4 GHz.