Recent Progress on High Output Power, High Frequency and Wide Bandwidth GaN Power Amplifiers

Masaru SATO  Yoshitaka NIIDA  Atsushi YAMADA  Junji KOTANI  Shiro OZAKI  Toshihiro OHKI  Naoya OKAMOTO  Norikazu NAKAMURA  

IEICE TRANSACTIONS on Electronics   Vol.E104-C   No.10   pp.480-487
Publication Date: 2021/10/01
Publicized: 2021/03/12
Online ISSN: 1745-1353
DOI: 10.1587/transele.2021MMI0001
Type of Manuscript: INVITED PAPER (Special Section on Microwave and Millimeter-Wave Technologies)
GaN power amplifier,  InAlGaN/GaN HEMT,  millimeter-wave,  power amplifier,  transmission line transformer,  wide bandwidth,  

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This paper presents recent progress on high frequency and wide bandwidth GaN high power amplifiers (PAs) that are usable for high-data-rate wireless communications and modern radar systems. The key devices and design techniques for PA are described in this paper. The results of the state-of-the art GaN PAs for microwave to millimeter-wave applications and design methodology for ultra-wideband GaN PAs are shown. In order to realize high output power density, InAlGaN/GaN HEMTs were employed. An output power density of 14.8 W/mm in S-band was achieved which is 1.5 times higher than that of the conventional AlGaN/GaN HEMTs. This technique was applied to the millimeter-wave GaN PAs, and a measured power density at 96 GHz was 3 W/mm. The modified Angelov model was employed for a millimeter-wave design. W-band GaN MMIC achieved the maximum Pout of 1.15 W under CW operation. The PA with Lange coupler achieved 2.6 W at 94 GHz. The authors also developed a wideband PA. A power combiner with an impedance transformation function based on the transmission line transformer (TLT) technique was adopted for the wideband PA design. The fabricated PA exhibited an average Pout of 233 W, an average PAE of 42 %, in the frequency range of 0.5 GHz to 2.1 GHz.