InP electronics industry
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ncreasing the operating frequency at 340 GHz, a frequency window of size is a very important consideration DARPA’s
of transmitters and detectors can low absorption from atmospheric for many government applications, funding of the
produce a range of benefits. These gases. Imaging systems at this according to DARPA program development of
include communication at higher data frequency promise to offer two manager John Albrecht. “Consider a the building
rates and identification of objects significant benefits over existing helicopter attempting to navigate a blocks for
that are highly absorbing at these equivalents at other frequencies. dust storm. While millimeter-wave imaging
higher frequencies. Imaging systems Imagers operating at far higher radiation offers a way to see through systems based
can also be improved, because frequencies are of limited use in the dust, the size of the millimeter on sub-
switching to higher frequencies can dusty, foggy and smoky conditions, wave imager – generally about one millimeter wave
slash the size of these systems. and 340 GHz systems could deliver meter – is too large to be practical. A frequencies
far more informative images, thanks sub-millimeter-wave imager can do could aid US
The latter benefit has encouraged the to greater penetration of the radiation the job with an aperture size that will helicopter pilots
US Defense Advanced Research at this frequency. Imagers at the fit onto the platform.” in dusty, foggy
Projects Agency (DARPA) to fund 340GHz frequency should also be and smoky
two consecutive programs that far more compact than lower The first phase of the SWIFT conditions.
require the re-defining of the state-of- frequency counterparts operating at program focused on the development CREDIT:
the-art for high-frequency transistors millimeter waves, because it should of 340 GHz amplifiers and detectors. US Navy
and associated circuits. The first, be possible to realize the same Efforts were restricted to III-V
Sub-millimeter Wave Imaging Focal spatial resolution with an aperture technologies, because these can
Plane Technology (SWIFT), kicked-off that is an order of magnitude smaller. form compact devices that are easily
in February 2006 with the goal of integrated with other pieces of
building an imaging system operating This substantial reduction in aperture electronics. Most of the targets for
DARPA propels InP electronics
towards a terahertz
DARPA is driving the development of ultra-high-frequency emitters and receivers
based on InP HEMTs and HBTs. If successful, this effort could ultimately lead to the
manufacture of imaging systems that enable helicopter pilots to navigate with greater
confidence in foggy, smoky and dusty conditions. Richard Stevenson investigates.
October 2009
www.compoundsemiconductor.net 33
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