Microwave research brings 100 Gbps within reach

Swedish researchers have designed a microwave transmitter circuit with a transmission rate of 40 Gbps, which is twice as fast as the previous world record.

Fewer cords, smaller antennas and quicker video transmission. This could be the result of a new type of microwave circuit designed at Chalmers University of Technology in Sweden.

With an increasing number of users, higher demands on image quality and more wireless systems, producing methods for transmitting enormous amounts of data through the air with the right speed poses a major challenge.

The solution might be to use higher frequencies than those in use today, from 100 gigahertz and higher, since this would give access to a larger band of empty frequencies, enabling a higher data rate.

Researchers all over the world are working to produce data circuits that can transmit and receive signals that are strong enough at these higher frequencies.

A Swedish research group from Chalmers University of Technology and Ericsson has already been successful.

“We have designed circuits for signals at 140 gigahertz, where we have a large bandwidth. In laboratory testing, we have achieved a transmission rate of 40 gigabit data per second, which is twice as fast as the previous world record at a comparable frequency,” says Herbert Zirath, who is a professor in high-speed electronics at Chalmers. He is also employed by Ericsson Research on a part-time basis.

Zirath says that indium phosphide semiconductor materials development has enabled manufacture of circuits that can transmit high frequency signals with sufficiently high power.

The 140 GHz transmitter chip, containing an I-Q modulator, a three-stage amplifier and a x3 frequency multiplier for the local oscillator. The chip size is 1.6 x 1.2 mm. Image: Sona Carpenter.

Some of the applications for quicker wireless data transmission include major cultural and sports events where high-resolution live films need to be transmitted to screens without any delay or long cables, and communication within and between the large computer rooms where our digital files end up when we place them in ‘the cloud’.

The fast circuits are of interest to Ericsson in terms of transmitting signals to and from base stations and cellular towers.

The next step for the project, funded by the Swedish Foundation for Strategic Research, involves moving from the laboratory to the outdoors to test the circuits under real circumstances.

Even though there are many aspects that have to fall into place for successful data transmission, Zirath is not worried. Within a few years, the goal within the project is to demonstrate wireless data transfer of 100 gigabit per second.

“I believe it is only a matter of a couple of years before our circuits will be used in practical applications.”