23 July 2010


Panasonic claims GaN transistor power density record of 2.4W/mm at 60GHz 

Panasonic Corp of Osaka, Japan says that it has developed a high-power gallium nitride (GaN) transistor for long-distance communication at millimeter-wave frequencies, and has used it to fabricate a 25GHz wireless transceiver. The device exhibits maximum output power of 10.7W at 25GHz, enabling communication over 84km in theory.

The high-power GaN transistor is fabricated on a silicon substrate, making it compatible with mass production on large-diameter wafers. Panasonic says that a novel epitaxial structure on Si improves the crystal quality, resulting in high drain current of 1.1A/mm with high carrier concentration. A metal-insulator-semiconductor (MIS) gate structure with crystalline silicon nitride (SiN) film used as a gate insulator greatly increases the gate breakdown voltage, and thus a high drain voltage of 55V can be applied to the device.
Panasonic says that the high current and high breakdown voltage of its proprietary GaN device enables record power output for a GaN-on-Si transistor of 10.7W at 25GHz, as well as record power density for GaN transistor of 2.4W/mm at 60GHz.

The transceiver that was fabricated uses orthogonal frequency division multiplexing (OFDM), which is suited to high-capacity data communication. The averaged output power of 2W out of the 10W from the GaN transistor can achieve 84km communication in theory. The high-power GaN transistor enables far longer reach than that for conventional GaAs transistors, it is claimed. Panasonic reckons that the GaN transistor is promising for future long-distance millimeter-wave communication systems at high speed and high data capacity.

Applications for 18 domestic and three overseas patents have been filed. The development work is partially supported by ‘The research and development project for expansion of radio spectrum resources’ of Japan’s Ministry of Internal Affairs and Communications. 

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