Design of high-efficiency broadband power amplifier based on split-ring resonator input matching network

In this letter, a novel design method of split-ring resonator (SRR) as the input matching network (IMN) of power amplifier (PA) is proposed. Compared with conventional microstrip lines, SRR is capable of providing necessary harmonic short-circuit while achieving broadband impedance matching. Applying the even-odd-mode theory, the impedance transformation characteristics of SRR are analyzed and show SRR can perform accurate impedance matching. To verify the proposed method, a PA is designed and implemented, the input impedance of 10-W GaN transistor is well matched to the source impedance by the SRR IMN in the operation band of 1.0-3.0 GHz. The measurement results show that the maximum drain efficiency of PA can reach 79.5% with 41.8 dBm of average output power in the operation band.