Power Amplifiers With Frequency-Selective Matching Networks

• Published in: IEEE transactions on microwave theory and techniques Vol. 69; no. 1; pp. 697 - 708
• Main Authors: Estrada, Jose Antonio, Montejo-Garai, Jose R., de Paco, Pedro, Psychogiou, Dimitra, Popovic, Zoya
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 5G mobile communication; Band-pass filters; Bandwidths; Ceramic; Co-design; coaxial resonators; coupling matrix; Couplings; Efficiency; Frequency response; GaAs; Gallium arsenide; Gallium nitride; GaN; Impedance; Integrated circuits; Matching; Microwave filters; Millimeter waves; MMIC (circuits); MMICs; monolithic microwave integrated circuit (MMIC); Power amplifiers; power amplifiers (PAs); Rejection; RF filters; Transistors
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2020.3020097

In this article, we demonstrate a method for codesign of filtering matching networks for power amplifiers (PAs) with the desired frequency response, improved efficiency, and reduced footprint. The microwave transistor operates with high efficiency with a specific complex-impedance load, and this requires the development of a theory for filter matching network design with arbitrary complex-impedance ports. The formulation is first developed and then applied to a simple second-order filter and a fourth-order filter with cross couplings and transmission zeros and verified in the experiment. A single-stage high-efficiency 4.7-GHz, 4-W hybrid GaN filter-PA (FPA) within a sub-6-GHz 5G band is designed, built, and characterized. The port impedances are determined by load- and source-pull for an efficiency-power tradeoff. The measured performance shows a gain of 15 dB, PAE = 55% with 9% fractional bandwidth, and 10-dB rejection at 4.5 and 5 GHz. Comparison with a cascaded PA-filter circuit shows a 25% lower loss with the same rejection and a reduced footprint with the same rejection. A GaAs monolithic microwave integrated circuit (MMIC) FPA at 28 GHz (millimeter-wave 5G FR2 band) is also designed and measured with a second-order output matching filter, demonstrating 8-dB gain, 200 mW of output power, and PAE = 30% with a rejection of 8 dB at 26.5 and 29.6 GHz.