Toshiba Announces Gallium Nitride Power FET with World's Highest Output Power in Ku-band



    --Achievement of 65.4W Output Power at 14.5GHz--

    TOKYO, October 8 /CNW/ - Toshiba Corporation today announced that it has
developed a gallium nitride (GaN) power field effect transistor (FET) for the
Ku-band (12GHz to 18GHz) frequency range that achieves an output power of
65.4W at 14.5GHz, the highest level of performance yet reported at this
frequency band. The main application of the new transistor will be in base
stations for satellite microwave communications, which carry high-capacity
signals, including high-definition broadcasts. Toshiba plans to start sample
shipment of the new power FET by the end of 2007 and to go into mass
production by the end of March 2008.

    Advances in Ku-band microwave amplifiers focus on replacing the electron
tubes conventionally used at this bandwidth with semiconductors, particularly
GaN devices, which offer advantageous high power characteristics at higher
microwave frequencies.

    The new power FET has a high electron mobility transistor (HEMT)
structure that Toshiba has optimized for the Ku-band. The company replaced
source wire bonding with via hole technology(1) to reduce parasitic
inductance, and also improved overall design of the matching circuit for
practical application at Ku-band frequencies.

    Demand for GaN power FET for radars and satellite microwave
communications base stations is growing steadily, both for new equipment and
replacement of electron tubes. Toshiba will meet this demand with early
commercialization of its new Ku-band power FET.

    Full details of the new GaN power FET will be presented at the European
Microwave Conference 2007, in Munich, Germany from October 8 to 12.

    Background and development aims

    Ever increasing communications flows in satellite microwave
communications are driving demand for higher output power in signal amplifying
devices, as is development of more powerful radar systems. Demand is
particularly strong for GaN devices, which offer advantages over conventional
gallium arsenide devices in heat dissipation and high power performance
characteristics at high frequency.

    Toshiba has taken the lead in applying GaN technology to power FET for
microwave frequency applications. The company directed its initial efforts to
the development and marketing of power FET for the 6GHz band (2005) and 9.5GHz
(2006) band, and developed devices that achieved the worlds highest output
power at those frequencies. The company has now extended its line-up to
14.5GHz. Toshiba will continue development for the 18GHz to 30GHz frequencies
(Ka-band) and beyond.

    Outline of development

    1. Device technology

    Toshiba achieved the outstanding performance of the new FET by optimizing
the composition and thickness of the AlGaN and GaN layers formed on the highly
heat-conductive silicon carbide (SiC) substrate of the HEMT structure. To
assure high performance at Ku-band frequencies, Toshiba has applied a shorter
gate length of below 0.3 microns, and optimized the shape of each electrode
and element configuration to enhance heat dissipation.

    2. Process technology

    To reduce the parasitic inductance and improve higher frequency
performance, Toshiba developed a unique technology for forming via holes,
which pass from the surface source electrode through the chip to the ground.
Success in forming via holes in SiC substrate, recognized as a highly
demanding process, is a breakthrough in development of the new FET.

    As gate lengths shorten, suppression of current leakage at the gate
electrode is essential for achieving high level performance. A unique overcoat
process applied around each gate electrode contributes to suppressing gate
leakage to 1/30 that of Toshiba's conventional approaches. Electron beam
exposure technology is applied in order to secure stable processing of gate
lengths below 0.3 micron meters.

    
    Key characteristics
    ----------------------------------------------------------------------
    Linear gain                     8.2dB
    ----------------------------------------------------------------------
    Saturation power                65.4W
    ----------------------------------------------------------------------
    Drain voltage                   30V
    ----------------------------------------------------------------------
    Operating frequency             14.5GHz
    ----------------------------------------------------------------------
    Chip size                       3.4mm x 0.53mm
    ----------------------------------------------------------------------
    Package size                    21.0mm x 12.9mm (external dimension)
    ----------------------------------------------------------------------
    

    (1) A technology of forming through hole and filling metal electrode in
the hole for connecting surface source electrodes to the backside ground
electrode, that enables to reduce the parasitic inductance, and thus, to
improve high frequency performance.

    Note

    Information in the press releases, including product prices and
specifications, content of services and contact information, is current on the
date of the press announcement, but is subject to change without prior notice.




For further information:

For further information: Toshiba Corporation Junko Furuta,
+81-3-3457-2105 Corporate Communications Office Fax: +81-3-5444-9202
http://www.toshiba.co.jp/contact/media.htm

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