Manufacturing Bits: Nov. 4

World’s fastest IC amplifier; photonic pressure sensors; photonics research center.


World’s fastest IC amplifier
Northrop Grumman has set a record for the world’s fastest integrated circuit amplifier.

The record has been recognized by officials from Guinness World Records. The amplifier uses 10 transistor stages to reach an operating speed of one terahertz, or one trillion cycles per second. This surpassed the company’s own record of 850 billion cycles per second set in 2012. Terahertz is a slice of the electromagnetic spectrum that lies between microwaves and infrared light waves.

Developed on behalf of DARPA, the integrated circuit is based on a 25nm indium phosphide high-electron mobility transistor, which measures at a gain of 10 decibels at 1-THz and nine decibels at 1.03-THz. In comparison, today’s smartphones operate at 1- to 2-GHz.

For years, researchers have been looking to exploit the frequency bands above 300-GHz. The terahertz level has proven to be challenging, due to the lack of effective means to generate the necessary high-frequency signals. In addition, electronics using solid-state technologies were unable to access sub-millimeter wave (sub-MMW) frequencies. This was due to insufficient transistor performance. The compromise option was to use frequency conversion to multiply circuit operating frequencies up from millimeter wave frequencies.

As a result, DARPA started the Terahertz (THz) Electronics program. The goal was to develop the device and integration technologies that operate at center frequencies exceeding 1-THz. This technology is targeted for imaging, radar, spectroscopy and communications.

Block diagram of a terahertz transceiver (Source: DARPA)

Block diagram of a terahertz transceiver (Source: DARPA)

Northrop Grumman has reached the lofty target in the program. The record-breaking circuit is part of the company’s three-phase contract with DARPA to demonstrate transistor-based electronics operating at 670-GHz, 850-GHz and 1-THz. “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,” said Dev Palmer, DARPA program manager, on the agency’s Web site. “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.”

Photonic pressure sensors
The National Institute of Standards and Technology (NIST) has developed what the agency claims is the world’s first photonic pressure sensor.

The sensor, dubbed the fixed-length optical cavity (FLOC), could one day replace traditional mercury pressure sensors. Traditional sensors, sometimes called manometers, are used to calibrate today’s commercial equipment.

The FLOC could be used as a factory-floor pressure instrument in various industries, such as semiconductor, glass and aerospace. A variation on the FLOC could improve the dimensional analyses on chips using lasers, by allowing them to track the index of refraction of air in real time, according to NIST.

The FLOC is about the size of a travel mug and has a resolution of 0.1mPa (millipascal or thousandths of a pascal). This compares to the mercury manometer’s resolution of 3.6mPa. This is 36 times better than NIST’S official U.S. pressure standard system, which is a 3-meter-tall column of liquid mercury that extends through the ceiling of the calibration room.

The FLOC system setup, with laser-directing optics (right), copper-enclosed optical cavity (center), and output signal on a computer monitor (left).  (Source: NIST)

The FLOC system setup, with laser-directing optics (right), copper-enclosed optical cavity (center), and output signal on a computer monitor (left). (Source: NIST)

Traditional pressure sensors rely on changes to the height of a column of mercury. Mercury is also a neurotoxic substance. The hazards posed by mercury have prompted a global effort to cut or phase out this substance from products and manufacturing.

The mercury-free FLOC consists of a temperature-controlled optical cavity, which contains of two channels. One channel is flooded with nitrogen gas and the other is a vacuum. A beam of low-power red laser light is locked to each channel. Some of the light from each channel is allowed to exit the FLOC, where the beams combine to form an interference pattern.

So far, the technique is accurate to within 0.005% or 50 parts per million (ppm). NIST will try to drive this accuracy below the 5 ppm range. Still, the FLOC is 100 times faster than the standard mercury manometer. “It can do in a second what the big mercury manometer takes about a minute and a half to do,” said Jay Hendricks of NIST on the agency’s Web site.

Photonics research center
Nanyang Technological University (NTU) and the University of Southampton have jointly established a photonics and optics research center in Singapore.

The $80 million center, dubbed The Photonics Institute, is located at NTU in Singapore. It is funded and supported by industry partners and various national agencies, including A*STAR, DSO National Laboratories, the Economic Development Board Singapore, the Ministry of Education and the National Research Foundation.

The Photonics Institute will comprise of five different research centers–Centre for Optical Fibre Technology; Centre for Disruptive Photonic Technologies; LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays; Centre for Optical & Laser Engineering; and OPTIMUS! Photonic Centre of Excellence.

NTU also unveiled Singapore’s first fiber optic research manufacturing facility. It is housed at one of the institute’s five research centers. The new institute will have a total of 120 scientists and staff from its five research centers, with a combined floor space of 4,000 square meters.

The Photonics Institute will be headed by three co-directors. They are NTU professors Tjin Swee Chuan and Nikolay Zheludev, as well as David Payne, professor and director of the Optoelectronics Research Centre and Zepler Institute at Southampton. Zheludev, who is also the director for the Centre for Disruptive Photonic Technologies, said the new institute is aimed at “developing disruptive ideas in next-generation photonics.”

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