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2 March 2007


KDDI and Fujitsu develop practical GaN HEMT-based high-efficiency amplifier for mobile WiMAX

After starting joint development in May 2006, telecoms company KDDI Corp and Fujitsu Ltd (both of Tokyo, Japan) have announced joint development of a practical high-efficiency amplifier (based on gallium nitride HEMT technology developed by Fujitsu Laboratories Ltd) for the IEEE 802.16e-2005 mobile WiMAX wireless broadband communications protocol.

To reduce both infrastructure and operating costs required for mobile WiMAX systems, KDDI has been exploring ways to make base-stations smaller and more energy-efficient. Fujitsu has optimized the design of the amplifier circuits for higher efficiency and improved its 3G-proven digital pre-distortion technology (distortion-compensation technology in which a signal that can offset the distortion generated by an amplifier is added in advance to the amplifier’s input signal). The resultant prototype transmitter amplifier achieves power efficiency of about 30% with 25W power output operating in the 2.5GHz frequency band (double the efficiency of conventional amplifiers used with currently available 3G systems, it is claimed).

Since amplifiers can dictate base-station performance, high efficiency can enable equipment benefits such as downsizing, lighter weight, greater power efficiency, less noise, and reduced maintenance. Deployment is expected to roughly half the size and power requirements of outdoor base-stations compared to conventional amplifiers, enabling a significant reduction in equipment space requirements. Improved efficiency also enables downsizing of collateral infrastructure such as air-conditioning equipment and power sources (e.g. back-up batteries), further reducing the costs of mobile WiMAX base-stations. The development paves the way for practical use of GaN HEMT-based high-efficiency amplifiers, says Fujitsu.

Fujitsu aims to enable practical use of the amplifier for mobile communication base-stations, including mobile WiMAX. From this year, in addition to embedding it into systems, Fujitsu plans to initiate a standalone business for power amplifiers.

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