Co-Design of Multi-Band High-Efficiency Power Amplifier and Three-Pole High- $Q$ Tunable Filter

This letter reports a novel methodology for co-design of broadband power amplifiers (PAs) and high- Q tunable filters. It is for the first time demonstrated that the tunable filter´s input port can be synthesized to directly match the transistor´s output, thus eliminating the conventional broadband/band-reconfigurable matching network of the PA. This leads to minimized circuit size, volume, and loss. In this letter, a three-pole tunable bandpass filter is designed as the output matching network of a 10 W GaN PA, yielding optimal fundamental and harmonic impedances. Simulation and measured results show that the co-designed PA-filter module exhibits desired Chybeshev filter behavior while achieving efficient PA performance in the passband over a 400-MHz tuning range from 2.95-3.35 GHz. Specifically, 51%-67% efficiency, ≈ 10 W output power, ≈ 10 dB gain were measured throughout the entire frequency range.