---

---

---

---

Science Current Events and Science News RSS Feeds

---

---

Email a Friend Printer Friendly

Chips for future multimedia radio systems

September 03, 1999

Millions of people surf the Internet, and their number is constantly increasing. But users regularly have to contend with bottlenecks when trying to access the net, or long periods of waiting while downloading sophisticated multimedia applications, such as video sequences for home learning. Radio systems provide a way to avoid the "traffic jam". For high-speed data transmission, future systems will broadcast in the gigahertz range. For comparison: the UHF band lies in the 100-megahertz frequency range. Researchers at the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg are now developing monolithic integrated microwave and millimeter wave circuits - MMICs - for broadcasting stations. A wide variety of different functions can be integrated on a single chip, with no complicated assembly or contact techniques required.

Existing broadcasting systems almost all function in a one-way direction, with one transmitter sending information to many receivers. But in future, interactive systems for two-way communication will come to the fore. This will call for transmission and receiver units for both the broadcasting center and the end user. "In this respect, the high frequencies have an advantage," emphasizes Michael Schlechtweg of the IAF. "The higher the frequency, the smaller the antennas can be. The units for transmitting and receiving the broadcast data will be no bigger than a shoe box."

The key components of the transmitter units are power amplifiers. The circuits required are being developed by the engineers in Freiburg. The basic material is gallium arsenide, which is used in semiconductors. Components made of this material are extremely versatile and of high performance. The possibility of manufacturing them cost-effectively and in large identical quantities makes them attractive for numerous applications in information technology.

In collaboration with Alcatel in Stuttgart, the IAF researchers have developed an MMIC for use in transmitters at broadcasting stations. The circuit operates at a frequency of 28 gigahertz and has a maximum output of 850 milliwatts. Field trials have meanwhile successfully demonstrated the transmission of multimedia data.

For further information:
Dr. Michael Schlechtweg
Phone: +49 7 61/51 59-5 34
Fax: +49 7 61/51 59-1 11
email: schweg@iaf.fhg.de
Fraunhofer-Institut für
Angewandte Festkörper-
physik IAF
Tullastrasse 72
D-79108 Freiburg
Press contact:
Dr. Roland Diehl
Phone: +49 7 61/51 59-4 16
Fax: +49 7 61/51 59-1 11
email: diehl@iaf.fhg.de
http://www.iaf.fhg.de

Fraunhofer-Gesellschaft