Ku-Band 70-/30-W-Class Internally Matched GaN Power Amplifiers With Low IMD3 Over a Wide Offset Frequency Range of Up To 400 MHz

• Published in: IEEE journal of solid-state circuits 2021-09, Vol.56 (9), p.2635-2646
• Main Authors: Yoshioka, Takaaki, Harauchi, Kenji, Sugitani, Takumi, Maehara, Hiroaki, Yamasaki, Takashi, Ichinohe, Hiroaki, Miyashita, Miyo, Yamamoto, Kazuya, Goto, Seiki
• Format: Article
• Language: English
• Subjects: <italic xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">Ku -band; Circuit design; Frequency ranges; Gallium nitride; Gallium nitride (GaN); Gallium nitrides; HEMTs; Intermodulation distortion; Logic gates; Matching; MODFETs; multi-carrier; power amplifier (PA); Power amplifiers; Resistors; satellite communication (SatCom); Satellite communications; Short circuits; Substrates; Wires
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2021.3098276

This study describes the Ku -band 70- and 30-W-class internally matched gallium nitride (GaN) power amplifiers (PAs) for multi-carrier satellite communications (SatComs). The GaN PAs maintain low third-order intermodulation distortion (IMD3) over a wide offset frequency range of up to 400 MHz, whereas in the Ku -band, one PA can deliver a high peak output power of approximately 70 W and the other PA, a peak output power of higher than 30 W. To realize a wide offset frequency operation, our proposed output-matching circuit includes three different types of difference-frequency short circuits, two of which are embedded into a tournament-shaped output-matching circuit inside the PA package and the rest is embedded into the drain bias feed placed outside the package. To verify the short-circuit design and its effectiveness, two different power classes (70 and 30 W), Ku -band GaN PAs, were designed and fabricated, and then, their output transfer characteristics focusing on IMD3 were measured. The measurements show that the 70-W-class GaN PA achieves a peak output power of 48.6 dBm while maintaining a linear output power of over 40 dBm and an IMD3 of less than −26 dBc over wide offset frequencies ranging from 1 to 400 MHz. The 30-W-class GaN PA maintains a linear output power of over 36.3 dBm and an IMD3 of less than −27 dBc over wide offset frequencies of up to approximately 600 MHz. To the best of the authors' knowledge, these PAs have a record output power level over a wide frequency range of 1-400 MHz or higher under the condition of a low IMD3 of less than −25 dBc, compared to previously reported Ku -band GaN PAs used for multi-carrier SatComs.