- Massive growth in home automation over next four years
- Gerard Lighting get SIDE distributorship
- Oracle opens Sydney digital hub – says 200 jobs will be created
- VR app sends users to exotic locales to meditate
FUJITSU has developed the world’s first compact 300GHz receiver capable of wireless communications at tens of gigabits per second.
Radio signals in the terahertz band (with frequency greater than 100GHz) allow for increases in usable frequency range and communication speed of more than 100 times compared with the 0.8-2.0 GHz range used by current mobile devices. This could be useful as bandwidth demands grow, especially for smartphones and tablets.
The new technology from Fujitsu combines a receiver-amplifier chip and terahertz-band antenna with a low-loss connection. This means the Japanese researchers were able to reduce the receiver's size to one tenth that of previous receivers, making use in mobile devices possible.
Details of this technology was presented at European Microwave Week (EuMW) 2015, the international conference which started on 6 September 2015 in Paris, France.
An issue with terahertz-band waves is that they attenuate sharply when propagating through space. The weak waves means a highly sensitive receiver is necessary to receive data.
In recent years, highly sensitive receiver-amplifier chips that work in the terahertz band have been developed by a number of companies, but because it was necessary to produce separate modules for the receiver-amplifier chip and the exterior antenna, which were then connected via a waveguide, the receivers produced were large and difficult to integrate into mobile devices.
Existing attempts at miniaturisation involved building the antenna directly into the receiver-amplifier module and eliminating the waveguide. The connection between the antenna and the receiver-amplifier chip is made through an internal printed-circuit substrate.
The problem then is that the most common materials for printed-circuit substrates for high-frequency waves are ceramic, quartz, or Teflon, but these material cause significant signal attenuation and loss of sensitivity when used with the terahertz band.
Fujitsu developed a low-loss technology for connecting terahertz-band antennas with already developed receiver-amplifier chips, This allowed it to build an integrated module with a cubic capacity at 0.75 of a centimeter (not including output terminals), which can be installed in mobile devices.
At the base of the connecting technology is a low-loss polyimide, which can be micro-fabricated into printed circuit boards.
The top and bottom layers of the printed-circuit substrate are grounded, and these layers are connected with through-hole vias. These vias need to be spaced apart by less than one-tenth of the signal's wavelength in order for the radio waves to be transmitted properly.
While polyimide as a material has a 10 percent higher loss than quartz, because its processing accuracy is more than four times higher, the through-hole vias can be placed within several tens of microns of each other, halving the loss as compared to a connecting circuit on a quartz printed circuit
In order to transmit the received signal from the connecting circuit on the printed-circuit substrate to the receiver-amplifier chip with low loss, Fujitsu developed mounting technology that faces the circuit-forming surface of the receiver-amplifier chip toward the printed-circuit substrate. This mounting technology is used for mounting millimeter-wave band collision-avoidance radar chips, but by using it with the polyimide circuit substrate-based low loss transmission technology, Fujitsu has successfully expanded the applicable frequencies into the terahertz band for the first time.
The use of this Fujitsu-developed technology will enable small devices to receive 4K or 8K HD video instantly, such as from a download kiosk with a multi-gigabit connection. It will also be possible to expand into such applications as split-second data transfers between mobile devices and split-second backup between mobile devices and servers.