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2020
Commercialization of X-band 300W output GaN HEMTs
(Sumitomo Electric Industries)

*** Discrete Devices ***

GaN HEMTs, whose development began in the late 1990s, were first used in cellular phone base stations in 2007. Ever since then, high-power devices ranging from tens to hundreds of watts have been developed in the microwave and millimeter wave bands, and have been widely used in cellular phone base stations and satellite communication systems [1] [2] [3].

Sumitomo Electric Industries has developed an internally matched amplifier with X-band (9 GHz band) operation and 300 W output power, consisting of two GaN HEMTs in parallel and an input-output matching circuit mounted inside the package [4] [5].

The basic part of the GaN HEMT consists of an AlGaN/GaN heterojunction epilayer formed by metal organic CVD (MOCVD) on a SiC substrate as shown in Figure 1. The layer is covered with a n-type impurity doped GaN layer to prevent generation of surface trap. Source, gate, and drain electrodes are provided on the surface, and the device is covered with insulating protection film [6]. A field plate structure is used to obtain high breakdown voltage characteristics. In order to ensure the power gain, power efficiency, and operating voltage required for X-band operation, and to prevent the phenomenon known as current collapse that occurs in GaN HEMTs, the device structure such as gate width is optimized and the device fabrication process is improved including epitaxial growth. As a result, a large saturation current of 1.1A/mm and a breakdown voltage of 290V at pinch-off, which is required for 50V operation, are realized.

The parallel operation of two GaN HEMT chips with a total gate width of 34 mm, consisting of 200 gate electrodes with a finger length of 170 µm arranged in an interdigitated structure, achieves the world's highest performance in the wide frequency range from 9 to 10 GHz with pulse operation (pulse width 100 µs, duty cycle 10%). An output power of 340W is achieved with a gain of 9.3dB and power-added efficiency of 38%. Both input and output ends are matched to an impedance of 50 Ω by a matching circuit consisting of a two-stage impedance transducer on a ceramic substrate.

Solid-state radars using GaN HEMT amplifiers with highly stable and coherent microwave signals based on a quartz oscillator can transmit frequency modulated long pulse signals. Using pulse compression technology, solid state radars can realize detection sensitivity equivalent or superior to magnetron radars with a transmission power of several hundred watts, about 1/100 of that of magnetron radars. Doppler signal processing technology can be used to provide the ability to detect the speed of moving objects. GaN HEMTs will have long-term reliability of more than 10 years and will enable radar maintenance costs to be kept lower. The commercialization of X-band 300 W output GaN HEMTs will accelerate the wide use of solid-state radars. [7].

Figure 1 Cross-sectional structure of GaN HEMT

Figure 1   Cross-sectional structure of GaN HEMT
(Plotted by Semiconductor History Museum of Japan with reference to Reference [6]

Figure 2 Inside of X-band 300W GaN HEMT

Figure 2   Inside of X-band 300W GaN HEMT
(Courtesy of Sumitomo Electric Industries, Ltd.)

[Reference]

  1. Semiconductor History Museum of Japan, Discrete Semiconductor Devices, etc., "2003: Development of a gallium-nitride HEMT for W-CDMA base stations (Fujitsu)"
    https://www.shmj.or.jp/museum2010/exhibi332.htm
  2. Kazutaka Inoue, Seigo Sano, Yasunori Tateno, Fumikazu Yamaki, Kaname Ebihara, Norihiko Ui, Akihiro Kawano, and Hiroaki Deguchi, "Development of Gallium Nitride High Electron Mobility Transistors for cellular base stations", SEI Technical Review, No. 71, pp. 89-93 (Oct. 2010)
  3. Akitada Kodama, Ken Osawa, Shigeyuki Ishiyama, and Miki Kubota, "High power and high efficiency C-band 100W GaN HEMT for space applications", SEI Technical Review, No. 90, pp.75-80 (April 2023)
  4. Makoto Nishihara, Makoto Aojima, and Naoyuki Miyazawa, "X-band 300W high-power GaN HEMT for marine radar systems", SEI Technical Review, No. 91, pp. 29-32 (Oct. 2020)
  5. New Products and Techniques, "300W compact package for X-band radar GaN HEMT power amplifier", SEI Technical Review, No. 99, p. 59 (Oct. 2024)
  6. Seigo Sano, Kaname Ebihara, Takashi Yamamoto, Tomio Sato, and Naoyuki Miyazawa, "GaN HEMTs for wireless communications", SEI Technical Review, No. 86, pp. 65-70 (Apr. 2018)
  7. Semiconductor History museum of Japan, Application Products, "2022: X-band all-solid-state radar using high-power GaN HEMTs (Japan Radio)"
    https://www.shmj.or.jp/application-products/ap202001.html

Ver.001: 2025/2/15