Spectrum

Record-breaking terahertz circuit could open new bands of the spectrum

Engineers backed by the Defense Advanced Research Projects Agency have achieved a significant electronics breakthrough with a solid-state amplifier integrated circuit clocked at 1 terahertz, or 1 trillion cycles per second, making it the fastest circuit ever measured. And it has the official recognition of Guinness World Records to prove it.

The Terahertz Monolithic Integrated Circuit, developed by Northrop Grumman under DARPA’s Terahertz Electronics program, broke the previous record of 850 gigahertz, set in 2012, also by Northrop engineers.

More significantly, circuits operating at that speed would open the door to using the sub-millimeter spectrum—that is, where the waves are smaller than a millimeter—which could lead to advances in small aperture communications, high-resolution imaging and radar, and spectroscopy.

“Terahertz circuits promise to open up new areas of research and unforeseen applications in the sub-millimeter-wave spectrum, in addition to bringing unprecedented performance to circuits operating at more conventional frequencies,” Dev Palmer, DARPA program manager, said in a statement. “This breakthrough could lead to revolutionary technologies such as high-resolution security imaging systems, improved collision-avoidance radar, communications networks with many times the capacity of current systems and spectrometers that could detect potentially dangerous chemicals and explosives with much greater sensitivity.”

DARPA describes the TMIC as a 10-stage common-source amplifier that showed “power gains several orders of magnitude beyond the current state of the art.” Gain, the agency said, is measured in decibels and describes how an amplifier increases power between a signal’s input and its output. TMIC showed a gain of nine decibels when operating at 1.0 terahertz and 10 decibels at 1.03 THz, DARPA said. (1 THZ is equal to 1,000 GHz. Wireless networks operate at 5.7 gigahertz; smartphones at 1 or 2 GHz.)

Access to sub-millimeter wave frequencies—those above 300 GHz—has proved difficult because of the inability of transistors to generate the necessary high-frequency signals. Until now, the only option was to use a frequency conversion approach to amplify signals, but that proved to be inefficient, in addition to increasing the size, weight and power requirement of devices, DARPA said.

TMIC could help create efficient devices that provide access to much-needed bands of the electromagnetic spectrum.

Demands on the spectrum are growing across all sectors, whether military, government or commercial. The Defense Department, while finding ways to accommodate all of its unmanned vehicles, sensors, wireless tactical networks and other technologies, also has to hand over 500 MHz of spectrum for commercial use by 2020. One part of DOD’s Electromagnetic Spectrum Strategy made public early this year is to find new, efficient ways to make use of the spectrum. TMIC could go a long way toward making that a reality.

About the Author

Kevin McCaney is a former editor of Defense Systems and GCN.

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