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Fujitsu Develops World's First GaN HEMT T/R Module Operating in the C-Ku Band

Enables consolidation of communications equipment into one compact module

Fujitsu Laboratories Ltd.

Kawasaki, Japan, June 06, 2011

Fujitsu Laboratories Ltd. today announced that it has successfully developed the world's first transmitter/receiver (T/R) module using gallium-nitride (GaN)(1)high electron mobility transistor (HEMT)(2) technology that features an output of 10 W and that operates in a wide bandwidth range of C-band, X-band, and Ku-band (C-Ku band)(3) radio frequencies over 6-18 GHz. By combining the world's best performing GaN power amplifier (PA) developed last year with the newly developed GaN low-noise amplifier (LNA), the researchers achieved a compact T/R module that generates a high-output.

This technology makes possible the integration of multiple types of communications equipment—each currently operated at a different frequency range—into a single module, making for the development of smaller, lighter radar equipment and wireless communication systems.

Details of this technology will be presented at the IEEE MTT International Microwave Symposium (IMS 2011) held in Baltimore, Maryland, starting June 5.


Gallium-nitride (GaN) is used as a blue-LED in traffic signal lights, and compared to the conventional semiconductor materials of silicon (Si) and gallium-arsenide (GaAs), it features a high saturation carrier velocity and relative resistance to the breakdown caused by voltage. Given these characteristics, GaN HEMTs—or transistors that use GaN—show promise for high-output and exceptionally efficient operations.


In line with the advance of a network-based society, radio wave demand in a variety of wireless systems is expected to increase even further. For example, aircraft radar typically switches between the C-band, which can detect distant objects and works well in rain, and the X- and Ku-bands which are able to measure physical objects with high-precision.

Currently, this demand for multiple frequency ranges requires different communications equipment each suited to their respective frequency band. However, a single T/R module capable of covering the entire C-Ku band range would meet a variety of needs, allowing systems to become more compact.

Figure 1: Usage scenarios for multifunctional radars operating across C-Ku bands

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Technical Issues

T/R modules are essential to operate multifunctional radar over a broad spectrum. Users therefore demand that T/R modules possess wideband features capable of operating across multiple frequency ranges, and high output performance so as to cover a wide area. To develop a T/R module with 10 W-class high output power over a wide broadband range, such as the C-Ku band, not only is a wideband PA and LNA required, but it is also critical to improve the T/R module's heat dissipation characteristics as heat generation intensifies in tandem with higher output levels.

In addition, it is also necessary to reduce signal losses in the input/output terminal to maintain frequencies up to 18 GHz. This is because at higher frequency ranges input/output signal losses increase in the terminal portion of the T/R module.

Figure 2: Photo and structure of GaN wide broadband T/R module

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Newly Developed Technology

By adopting a GaN HEMT, Fujitsu Laboratories developed a compact, high-output GaN HEMT T/R module that covers the ultra-broadband C-Ku spectrum (6-18 GHz).

Key features of the new technology are as follows:

  1. Improved heat dissipation with heat sink
    Fujitsu Laboratories developed an embedded heat sink structure that efficiently dissipates the heat generated at high output levels. The heat sink is built into the T/R module's multilayer alumina ceramic substrate. Compared to previous designs, heat dissipation improved by a factor of five times, enabling high output levels of 10 W.
  2. Lower signal losses in the signal input/output terminal portion
    Fujitsu Laboratories devised an ultra-broadband terminal structure that reduces the input/output terminal signal loss that occurs at higher frequencies. With the new terminal structure, high frequency signals passing through the module can be transmitted at up to 40 GHz, three times the frequency levels of previous designs.
  3. Development of a world-class, compact LNA
    In addition to the GaN HEMT PA featuring the world's highest output performance developed last year by Fujitsu Laboratories, the researchers have now developed a new LNA that uses GaN HEMT. Being a compact 2.7 × 1.2 mm, the LNA achieves a gain of 16 dB across 3-20 GHz, and noise figures of 2.3-3.7 dB, representing the world's best performance levels.

Figure 3: Photo and cross-sectional diagram of GaN wide broadband T/R module

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The new technology has enabled Fujitsu Laboratories to develop a compact T/R module measuring only 12 × 30 mm that operates across an ultra-wide broadband 6-18 GHz, with output power of 10 W.

This new technology will make it possible for a single T/R module to operate at multiple frequencies, paving the way for further system integration in broadband communications and radar systems that utilize various frequencies, meaning more compact and lighter equipment.

Future Plans

Fujitsu Laboratories plans intends for this technology to be put to use in a wide range of applications that require compact modules with high output across wide bandwidths, including wireless communications and radar systems.

  • [1] Gallium-nitride (GaN)

    GaN-based semiconductors are wide bandgap semiconductors that feature a higher breakdown-voltage (threshold) than conventional semiconductor materials, such as silicon (Si) or gallium-arsenide (GaAs).

  • [2] High-electron mobility transistor (HEMT)

    A field-effect transistor that utilizes the electron movement at the junction between two semiconductors with different band gaps—as electron mobility in HEMTs is faster than that of conventional semiconductors. Fujitsu led the industry with its development of HEMT technology in 1980, and HEMTs, as a core technology underpinning the network-based society, are currently used in a wide range of core technologies for IT applications, including satellite transceivers, mobile phones, GPS-based navigations systems, and broadband wireless networking systems.

  • [3] C-band, X-band, Ku-band

    These are common names for each frequency band. The C-band covers 4-8 GHz and is not prone to attenuation from rain or fog. Applications that employ the C-band include satellite communications, fixed wireless networking, wireless access networking, air-traffic control radar, weather radar, etc. The X-band covers 8-12 GHz and has only minimal impact from crosstalk and interference, thereby making it difficult to intercept or jam. The X-band is often used in satellite communications, air-traffic control radar, and weather radar. The Ku-band covers 12-18 GHz, and has only minimal impact from crosstalk and interference, thus making it difficult to intercept or jam. Ku-band applications include satellite communications and various types of radar.

About Fujitsu Laboratories

Founded in 1968 as a wholly owned subsidiary of Fujitsu Limited, Fujitsu Laboratories Limited is one of the premier research centers in the world. With a global network of laboratories in Japan, China, the United States and Europe, the organization conducts a wide range of basic and applied research in the areas of Next-generation Services, Computer Servers, Networks, Electronic Devices and Advanced Materials. For more information, please see:

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This press release has been revised as of December 17, 2018.

Date: 06 June, 2011
City: Kawasaki, Japan
Company: Fujitsu Laboratories Ltd., , , , , , , , , ,