The new device (data courtesy of Rohm and Osaka University)
The new device (data courtesy of Rohm and Osaka University)
[Click to enlarge image]
The structure of the device (data courtesy of Rohm and Osaka University)
The structure of the device (data courtesy of Rohm and Osaka University)
[Click to enlarge image]

A Japanese research group announced that it has realized 300GHz high-speed wireless communication (1.5 Gbps) with a small device by using oscillation and detection elements based on resonant tunneling diodes (RTDs.)

The research group consists of researchers from Rohm Co Ltd and Osaka University.

Currently, frequency bands lower than 275GHz are allotted for radio waves in Japan, and the frequency band for wireless communication using milliwaves is as narrow as 7GHz. To improve data transmission speed in a narrow frequency band, a more complicated modulation method is necessary, increasing power consumption.

On the other hand, frequency bands higher than 275GHz including terahertz waves are not allotted for radio waves, enabling to ensure a wider frequency band. As a result, it becomes possible to improve data transmission speed by using a simple modulation method without increasing power consumption.

However, oscillation and detection devices that can be used in a terahertz band are currently large and expensive. Therefore, it has been required to develop a small, simple device that can be used in a terahertz band for consumer use.

This time, the research group succeeded in reducing device size (to 1.5 x 3.0mm) by integrating antenna structures with improved radiation efficiency and directivity on a semiconductor substrate. The new device has an area that works as an oscillation device (frequency: 300GHz) and an area that works as a detection device depending on applied voltage.

As an oscillation device, it can generate oscillation just by applying voltage. As a detection device, it has a four times higher sensitivity than existing terahertz-band detection devices.

In addition, the research group realized a high-speed data transmission of 1.5Gbps and succeeded in wirelessly transmitting uncompressed high-vision video signals by developing an original modulation/demodulation system suited for RTD.

According to Rohm, the group realized the world's first terahertz wireless communication using such a small semiconductor device, and it will be possible to realize a super-high-speed transmission of about 30Gbps in the future. Furthermore, because one chip functions as both oscillation and detection devices, it is possible to communicate between multiple devices.