TRW/NASA team uses superconductors for infrared imaging

Engineers at the NASA Jet Propulsion Laboratory (JPL) in Pasadena, Calif., needed a low-power chip to run an infrared imaging system with superconducting digital electronics.

TRW/NASA team uses superconductors for infrared imaging

Engineers at the NASA Jet Propulsion Laboratory (JPL) in Pasadena, Calif., needed a low-power chip to run an infrared imaging system with superconducting digital electronics.

A tiny superconducting chip developed at TRW in Redondo Beach, Calif., met their needs. The chip performs high-speed digital signal processing like a conventional silicon integrated circuit, but consumes 1,000 times less electrical power, TRW officials say.

Funding for the chip came from the Ballistic Missile Defense Organization in Arlington, Va., and from NASA. Integrating the imaging system were engineers from TRW and NASA JPL. It includes the TRW-built superconducting analog-to-digital converter (ADC) chip coupled to the sensor, a Boeing-supplied focal plane array cooled to about 10 degrees above absolute zero.

"The improved imaging capability will help sensors track and image very faint or very cool objects in space, such as distant stars or incoming ballistic missiles in their midcourse phase," says Larry Eaton, TRW`s superconducting electronics program manager.

"Superconducting circuits greatly boost the speed of imaging systems, which operate at temperatures near absolute zero (10 degrees Kelvin or -273 degrees Celsius), while dramatically cutting overall size, complexity, power consumption and cost - all key advantages for any satellite," Eaton says.

The project represents the first time that designers have integrated a superconducting chip with a focal plane array, claim TRW officials. "TRW`s ADC circuit itself uses less than 40 microwatts, while the full chip consumes barely one-third of a milliwatt - about 1,000 times less power than a comparable silicon circuit - hence, it generates almost no heat," Eaton says.

"As a result, we were able to put the chip in the same compartment as the infrared sensors, which must be kept at about 10 degrees above absolute zero," he says. The test bed illustrates how small, low-power superconducting electronics can simplify the design and construction of focal plane array systems, Eaton adds.

"By converting the incoming signals to digital form at the focal plane, we eliminated the noise-susceptible analog transmission lines previously needed to carry the signals away from the focal plane," Eaton explains. "The removal of this potential noise source helps preserve the quality of the original signal, which will allow us to produce images of fainter objects at greater distances."

TRW`s ADC chip`s electronic elements are of niobium nitride. In production quantities, engineers expect the chip to operate 10 times faster and consume about 1,000 times less power than a comparable silicon-based ADC chip, claim TRW officials. - J.M.

For more information on the ADC chip and TRW, contact Jack Prichett by phone at 310-812-5227, by post at TRW Inc., One Space Park, Redondo Beach, Calif., 90278, or on the World Wide Web at http://www. trw.com.

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