Open AccessHarmonic‐tuned continuum mode active load modulation output combiner for the design of broadband asymmetric Doherty power amplifiers
Author(s) -
Naah Gideon,
He Songbai,
Shi Weimin,
Li Caoyu,
Nusenu Shaddrack Yaw
Publication year - 2019
Publication title -
iet microwaves, antennas and propagation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.555
H-Index - 69
eISSN - 1751-8733
pISSN - 1751-8725
DOI - 10.1049/iet-map.2018.5841
Subject(s) - amplifier , broadband , bandwidth (computing) , electronic engineering , electrical impedance , active load , power dividers and directional couplers , input impedance , engineering , wideband , power bandwidth , electrical engineering , voltage , rf power amplifier , telecommunications , transistor
The conventional Doherty output combiner limits the bandwidth of operation in the asymmetric Doherty power amplifiers (DPAs). In this study, an output combiner that is designed using a harmonic‐tuned continuum mode active load modulation technique is proposed with the main target of extending the bandwidth of operation in the asymmetric DPAs. Through this methodology, design equations are derived and multiple harmonic impedance solutions are provided. This offers greater freedom for designing the output combiner of the asymmetric DPA which consists of the impedance inverting network and the impedance transforming network. Moreover, enhancements in the efficiencies at back‐off and saturation power levels are made possible. The efficacy of the design strategy is demonstrated by the realised broadband asymmetric DPA prototype working within the band of 1.4–2.45 GHz. The experimental results have shown 54.55% bandwidth of operation, accounting for about 0.95–12.55% increment in bandwidth as compared with some recently published DPAs in the literature. Substantially, drain efficiencies within 35.5–52% at 6 dB output power back‐off level and 47.5–64.2% at peaking power level are also recorded from the experiments. The maximum output power and gain are recorded at 43.52 dBm and 13.03 dB, respectively.