industry InP electronics
rhombus4
Teledyne Records.
Scientific and
Imaging is “What we’ve accomplished since
developing then is to build a suite of circuits that
HBT-based demonstrate all the major active
circuits for functions that you would need in the
DARPA’s 340 GHz window,” explains Richard
terahertz Lai, the head of the company’s
electronics microelectronics products. This
program. includes fundamental oscillators for
Teledyne has a creating sub-millimeter-wave
strong frequency sources, power amplifiers
background in for boosting their intensity, and low-
this technology, noise amplifiers (LNAs) that increase
having already the intensity of a signal before it is
built 325 GHz detected. The IEDM results were
InP HBT power obtained on-wafer, and packages
amplifiers have now been developed to house
delivering these chips.
2.1mW at
6.1 % power- The IEDM presentation included
added details of a LNA that produced 15
efficiency dB of gain at 340 GHz. Since then
this amplifier’s operating frequency
has been increased to 350 GHz, and
the first phase were realized, with at 340 GHz, and suggested that it has been packaged into gain
those involved pioneering the much higher frequencies in transistor blocks with waveguides for coupling
fabrication of amplifiers and electronics were feasible,” explains radiation in to and out of the chip.
oscillators operating at frequencies Albrecht. “This was the inspiration
above 300 GHz. “In the process, that led to a new program entitled A more recent edition to Northrop
new infrastructure, benchmarks and terahertz electronics.” Its ultimate aim Grumman’s product portfolio is a 10
metrology were created that will is to treble the operating frequency mW power amplifier. Lai says that
open the sub-millimeter wave of the devices in the SWIFT the fabrication of this amplifier was
frequency domain for future designs program, while maintaining their one of the biggest challenges of the
and systems,” says Albrecht. impressive power, noise figure and program. The InP HEMTs used in
bandwidth characteristics. However, this type of amplifier have a relatively
More than 60 publications have it’s not just a follow-on to SWIFT, low breakdown voltage, and
stemmed from these achievements, says Albrecht: “The objective is to consequently a relatively low power
which have included the development develop the critical device and density, so fingers are added to
of 35 nm InP HEMTs, 0.3 µm-emitter integration technologies to realize boost the output.
HBTs, and monolithic integrated compact, high-performance
circuits operating at sub-millimeter electronic circuits operating at center NGAS embarked on the terahertz
wave frequencies. The only elusive frequencies exceeding 1.0 terahertz.” electronics program in April 2009,
goal was that of a 50 mW output and it is now working towards the
power for the power amplifier. One of the key contractors in both of phase I targets, which are defined at
DARPA’s programs is Northrop 670 GHz (see table for details).
Exceeding expectations Grumman Aerospace Systems Researchers are in the middle of
Given the great successes in phase I (NGAS). This company hit the performing some fundamental device
of the program, one would expect the headlines in late 2007 with the claim studies, and they are looking to
funding of the second phase to be a for the world’s first terahertz exploit HEMT and HBT technologies.
formality. But this has not happened transistor. The results produced by its
because DARPA believes that the ground-breaking InP HEMT were DARPA is also funding another team
best way forward is to pursue even presented at the International on its terahertz electronic program,
more ambitious targets. “The device Electron Devices Meeting (IEDM), which is being led by Teledyne
technology achieved unexpectedly and Northrop Grumman now has an Scientific and Imaging. This firm
high gain of typically 8dB per stage entry in the Guinness World played a smaller role in the SWIFT
34 www.compoundsemiconductor.net October 2009
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