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Oki Electric Power Transistor for Wireless Communications Achieves World's-Best Amplification Characteristics
Oki Electric Industry Co., Ltd. today announced a power transistor with dramatically improved amplification characteristics for wireless communications applications. Oki's new power transistor achieved a worldfs best 500 mS/mm figure for transconductance, an indicator of amplification performance. The transistor reduces the power consumption and space required for wireless communications systems in mobile phone base stations and wireless LANs. Oki developed the transistor in partnership with Professor Takashi Egawa at the Research Center for Micro-Structure Devices at the Nagoya Institute of Technology.
Tokyo, Japan, March 26, 2003 -- Oki Electric Industry Co., Ltd. (TSE: 6703) today announced a power transistor with dramatically improved amplification characteristics for wireless communications applications. Oki's new power transistor achieved a worldfs best 500 mS/mm figure for transconductance, an indicator of amplification performance. The transistor reduces the power consumption and space required for wireless communications systems in mobile phone base stations and wireless LANs. Oki developed the transistor in partnership with Professor Takashi Egawa at the Research Center for Micro-Structure Devices at the Nagoya Institute of Technology.
"This development marks a critical step toward broadening the applicability of this type of transistor, which we at Oki expect to be an essential device in the next generation of wireless communications systems," said Harushige Sugimoto, General Manager of the Corporate Research and Development Center at Oki Electric. "I believe this record high transconductance results from our sustained R&D dedication to innovative technologies."
The power transistor is composed of a GaN-HEMT (gallium nitride high electron mobility transistor) layer on a SiC (silicon carbide) substrate. It achieves a transconductance figure of 500 mS/mm, a dramatic improvement from Oki's previous high of 327 mS/mm. To improve amplification characteristics, Oki successfully fabricated T-shaped recessed gates, reduced gate length, and optimized the device structure. The transistor achieves high frequency performance that features a maximum oscillation frequency of 126 GHz and 67 GHz of current gain cut-off frequency.
The rapid increase of channels made necessary by growing communications volumes has increased the need to reduce power consumption and space per channel of mobile phone base stations and other wireless communications systems. With its improved amplification characteristics, Oki's new power transistor makes it possible to reduce the number of amplifier stages in transceiver equipment, providing precise response to this market demand.
Oki intends to further enhance the performance of the device by increasing power output and reducing costs, with plans to commercialize it for mobile phone base stations and wireless LANs. The company plans to begin sample shipments in the second half of the fiscal year ending March 31, 2004.
Structure of the Device:
(GIF file is available according to your request)
Glossary:
- High amplification characteristics:
High power output with low input signal power
- GaN-HEMT:
Gallium nitride high electron mobility transistor widely used for amplification equipment in mobile phones and information processing ICs for ultra high-speed optical communications. It provides almost 10 times higher power output than GaAs (gallium arsenide) ICs. GaN-HEMT also makes it possible to reduce the number of modules to one-tenth to one-fifth that required with current GaAs element module.
- T-shaped gate:
To achieve high power output, conventional I-shaped gate, requires wide and long gates, increasing the resistance of the gate electrode and decreasing operation frequency. A T-shaped gate electrode provides a larger cross-section and lower electrode resistance.
- Recessed gate:
The new device features a recessed HEMT gate, dramatically reducing the parasitic resistance of the transistor, while improving amplification and high frequency characteristics. It requires very difficult, high-precision fabrication technique rarely applied to GaN-HEMT elements.
Notes:
- The names of companies and products are trademarks or registered trademarks of the respective companies.
- Technology development was undertaken as an Ultra-Low-Loss Power Device Technologies Project by Ministry of Economy, Trade and Industry (METI) under the auspices of the R&D Association for Future Electron Devices (FED) supported by New Energy and Industrial Technology Development (NEDO).
About Oki Electric Industry Co., Ltd.
Founded more than a century ago in 1881, Oki Electric Industry Co., Ltd. is Japan's first telecommunications manufacturer, headquartered in Tokyo, Japan. Oki Electric provides customers with top-quality products, technologies and solutions for telecommunications systems, information systems and electronic devices through its corporate vision, "Oki, Network Solutions for a Global Society." Visit Oki's global web site at http://www.oki.com/.
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