A Simple Method of Designing High-Efficiency Second-Harmonic-Tuned Power Amplifier

This letter presents a simple method to realize high-efficiency second-harmonic-tuned (2HT) power amplifier (PA). Compared with other works, this method can realize optimum fundamental and second-harmonic impedance matching accurately, thus to achieve a relatively high efficiency through only controlling the first two frequencies. Besides, to avoid the problem of transmission line with high characteristic impedance in traditional dual-band bias network, offset double-sided parallel-strip line is introduced. For demonstration, a PA using Cree CGH40010 GaN HEMT is designed and fabricated. The measured peak power added efficiency and drain efficiency reach 80.4% and 84.2%, respectively, with a corresponding output power and gain of 40.4 dBm and 13.4 dB at 2 GHz under continuous wave signal.