Dual-band matching technique based on dual-characteristic impedance transformers for dual-band power amplifiers design

This study demonstrates a novel matching network synthesis technique that matches any arbitrary reflection coefficient seen by the active device at two uncorrelated frequencies to the standard 50 load. The proposed matching network is fully transmission line based and, hence, can be used in high-power applications at higher frequencies. Unlike previously reported dual-band matching techniques, this work proposes and discusses various ways to achieve realisable solutions for arbitrary frequency ratios that account for fabrication limitations. The proposed synthesis approach is validated with the design and fabrication of a 10 W gallium nitride (GaN)-based class-AB amplifier for code division multiple access and Worldwide Interoperability for Microwave Access applications at 1960 and 3500 MHz. The amplifier has 59.8 and 55.1 drain efficiencies at saturation in the first and second bands, respectively.