High-efficiency broadband power amplifier with split-ring resonator second harmonic output matching network

In this paper, a realization method for high-efficiency broadband power amplifier (PA) based on split-ring resonator (SRR) second harmonic output matching network (SHOMN) is presented. The SRR is composed of double rectangular rings, and it can flexibly match the second harmonic components to the high-efficiency impedance region in the Smith chart in a wide frequency band. Besides, the impedance transformation characteristic of SRR is derived, and the optimal output impedance is converted from the transistor drain to the output of SHOMN for accurate fundamental matching. For validation, a PA operating in 1.2-3.0 GHz is designed and fabricated for a 10-W GaN transistor. The measurement results show that the maximum efficiency can reach 78.3%; meanwhile, the average saturated output power is 41.0 dBm.