High-Efficiency Multiband Outphasing Amplifiers Using Streamlined Impedance Synthesis Methodology

This article introduces a novel network synthesis approach that streamlines the design of multiband outphasing power amplifiers (OPAs). By strategically factoring the global transmission matrix into cascaded subnetworks, the proposed approach reduces the conventional matrix synthesis problem to an adaptive impedance matching procedure, significantly enhancing design flexibility for multiband applications. A simplified real frequency technique (SRFT) is employed to construct adaptive matching networks, achieving high adaptability in dual- and tri-band operations. To experimentally validate the proposed methodology, both a dual-band OPA targeting the 2.6- and 3.5-GHz bands for LTE and 5G applications and a tri-band OPA covering 1.8, 2.6, and 3.5 GHz were fabricated using 10-W GaN HEMTs. Measurement results demonstrate outstanding performance: the dual-band prototype achieved peak output powers of 44.42 and 44.18 dBm with corresponding peak drain efficiencies of 75.4% and 74.6%, while the tri-band prototype achieved peak output powers exceeding 43.8 dBm across all bands with drain efficiencies above 66.8%. Even at a 6-dB output back-off, the tri-band amplifier maintains efficiencies exceeding 48.6% for all bands, effectively showcasing the superiority and practicality of the proposed design approach for high-efficiency multiband OPA realization. To the best of the authors’ knowledge, this is the first nonreconfigurable multiband OPA ever reported.