US claims THz transistor speed record

Northrop Grumman is claiming a speed record with “the fastest solid-state amplifier integrated circuit ever measured”.

Developed for US military lab DARPA, the ten-stage common-source amplifier showed 10dB gain at 1.0THz and 9dB at 1.03THz. The transistors are 25nm gate length indium phosphide (InP) HEMTs.

“Gains of six dB or more start to move this research from the laboratory bench to practical applications—nine decibels of gain is unheard of at terahertz frequencies” said DARPA programme manager Dev Palmer, “This opens up new possibilities for building terahertz radio circuits.”

Palmer envisages high-resolution security imaging systems, collision-avoidance radar, comms networks and chemical spectrometers using the technology.

DARPA has several THz programmes including ‘High frequency integrated vacuum electronics’ (HiFIVE), ‘Sub-millimeter wave imaging focal plane technology’ (SWIFT) and ‘Technology for frequency-agile digitally synthesised transmitters’ (TFAST), each building on the previous one.

Under DARPA programmes, Northrop demonstrated an 850GHz receiver in 2012, and 670GHz in 2010.

Northrop also showed THz operation in vacuum devices, when it revealed a micromachined 850GHz travelling wave tube last year. “DARPA-sponsored research has taken tools developed by the semiconductor and MEMS revolution and applied them to vacuum tube technologies,” said Palmer at the time.

“A decade ago, there was no consensus in the scientific community whether an integrated circuit operating at 1THz was technologically possible,” said Northrop THz programme manager William Deal. “An interdisciplinary team of scientists and engineers worked together in scaling all facets of our MMIC technology to enable the 1THz result. Now, as a result of DARPA’s investment in high-speed transistor processes, it will become routine to fabricate wafers containing thousands of THz integrated circuits.”

DARPA has plans to put the travelling wave tube in its ‘video synthetic aperture radar’ (ViSAR) – an attempt to create a TV-like 2d imager that can see through clouds using high frequency radio waves.

steve bush

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via Yuichun