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.