News Article

Japanese Firms Aim GaN Amp At Mobile WiMAX

Fujitsu and communications firm KDDI have made a prototype 25 W transmitter amplifier that is based on GaN HEMT devices.

Japanese technology giant Fujitsu is setting up a standalone business focused on power amplifiers for broadband wireless networks.

The company has now produced a prototype GaN HEMT transmitter amplifier, which it says is suitable for deployment in mobile WiMAX network equipment. It plans to embed the wide-bandgap semiconductor technology into RF systems used in base stations.

The new power amplifier business will be set up some time later this year.

Fujitsu and its subsidiary research wing Fujitsu Laboratories have been at the forefront of GaN HEMT and power amplifier development for many years, and have broken a series of performance records in the process (see related stories).

With mobile WiMAX now receiving backing from at least some of the major players in the wireless communications market, Fujitsu senses a market opportunity has finally arrived that can take advantage of its substantial investment in the GaN transistors.

In a joint development with communications company KDDI, also based in Japan, Fujitsu has been putting the final touches to these WiMAX amplifiers since May 2006.

The result is a prototype transmitter that produces a 25 W output at 2.5 GHz, and at a power efficiency of around 30 percent for orthogonal frequency division multiplexing (OFDM) 16QAM signals.

KDDI has been looking into how the GaN HEMT amplifiers can lead to smaller, more energy-efficient base station equipment that is also relatively maintenance-free when compared with existing systems.

"The deployment of this new amplifier technology is expected to reduce the size and power requirements of outdoor base stations by roughly half compared with conventional amplifiers," says Fujitsu. This is because the increased efficiency means that less waste heat is dissipated, and that air conditioning requirements are much reduced.

As well as the size reduction, using GaN also means that smaller back-up batteries are needed, which is expected to make a major contribution to reducing the cost of base stations required for mobile WiMAX.

• At last year s CS Mantech conference, Fujitsu s GaN HEMT research team lead by Toshihide Kikkawa won the award for best paper for work that proved the reliability of the devices - a crucial development for any new technology. members can read an article written by Kikkawa that is based on that award-winning paper here. The article was published in the July 2006 issue of Compound Semiconductor magazine.

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