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ScienceDaily (Feb. 12, 2009) — New imaging and high capacity wireless communications systems are one step closer to reality, thanks to a millimeter wave amplifier invented at the University of California, San Diego and unveiled on Feb 11, 2009 at the International Solid-State Circuits Conference (ISSCC) in San Francisco, Calif.

The new silicon-based amplifier marks progress toward high capacity wireless communications systems that will operate at millimeter wave frequencies (70-110GHz) and could provide data transfer rates as fast as 10 Gigabits per second over a kilometer. Toward this goal, the new amplifier provides both high gain (the ability to increase the volume of a signal) and high bandwidth (the ability to do it over a broad range of tones). It has a direct transmission line path from the input to the output that carries electromagnetic waves—undisrupted—across the surface of a silicon chip. Amplification "stages" along this transmission line boost the signal power by monitoring the signal amplitude and generating feedback in just trillionths of a second, feedback that injects additional energy in phase to the signal. The amplifier provides record-breaking gain of 26-30dB at 100GHz and allows wave propagation along the chip surface.

James Buckwalter, an assistant professor in the Department of Electrical and Computer Engineering at UC San Diego's Jacobs School of Engineering, invented the amplifier and named it the Cascaded Constructive Wave Amplifier.

"Cascaded constructive wave amplification is a new circuit architecture that can push silicon into new operating regimes near the fundamental limits of Moore's Law and allow the ultra high data rates that the millimeter wavelength range of the electromagnetic spectrum offers," explained Buckwalter.

The millimeter wavelength range of the electromagnetic spectrum is relatively unexplored for commercial use, in part, because it has been difficult and expensive to build the necessary high frequency amplifiers. Many of today's millimeter wave amplifiers, for example, require exotic and expensive semiconductor materials.

"We're exploring how silicon can play a role at frequencies exceeding 100 Gigahertz. Silicon has the advantage of allowing inexpensive integration of microwave and now perhaps millimeter wave components," said Buckwalter.

A is for Amplification

Today's Wi-Fi and WiMax systems operate at a frequency of 2.5-5GHz and are capable of handling megabits of information per second. "If you want higher data rates, you need to find ways to transmit information wirelessly at rates faster than what is available at 2.5 Gigahertz. This new amplifier is aimed at opening millimeter wave frequency bands, where much more bandwidth are available and where higher data transfer rates, as fast as 10 Gigabits per second over a kilometer, are possible," explained Buckwalter.

Point-to-point wireless communication is a low-cost approach to getting optical fiber speeds. "You could use this amplification method to boost signal strength of a 100 Gigahertz signal from the transmitter in your ISP and also at the receiver in your home to detect the signal," explained Buckwalter.

Feedback Tames the Wave

"The really cool thing about this chip is that it's the first time traveling waves have been amplified along an uninterrupted transmission line...we've found a new architecture that allows higher gain than what people supposed for waves traveling near the speed of light on silicon chips," said Buckwalter.

The periodic amplification stages along the transmission line are crucial to the amplification process. They monitor waves as they propagate through the transmission line and spontaneously inject energy into the wave without interrupting its propagation down the transmission line.

In particular, the strength of the wave is constantly monitored at the output side of each amplification stage. Feedback is provided through a fast transistor that feeds energy into the input of the transmission line and hits the wave with that energy 2.5 trillionths of a second later—a quarter of the wave's period. In this way, the wave is constantly being strengthened as it moves uninhibited through each of the amplification stages along the transmission line.

This new amplifier design is distinctly different from existing amplifier technologies. The new Cascaded Constructive Wave Amplifier provides high gain—the signal gain increases exponentially with the number of amplification stages—without absorbing and regenerating the wave energy. The cascaded amplifiers that are found in all cell phones also have high gain——but they absorb and regenerate signals.

"We've taken a wave that travels along the surface of the silicon near the speed of light and found a way to amplify the signal strength without interrupting the wave," said Buckwalter. "We have found a way to tame millimeter waves on silicon."

ISSCC 2009 Paper citation: "A 26dB Gain, 100GHz Si/SiGe Cascaded Constructive Wave Amplifier," by James Buckwalter and Joohwa Kim from the Department of Electrical and Computer Engineering from the UC San Diego Jacobs School of Engineering.

This work was supported through a DARPA Young Faculty Award to James Buckwalter.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of California - San Diego, via EurekAlert!, a service of AAAS.

Note: If no author is given, the source is cited instead.

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10:28am Saturday 4th December 2010

THE widow of Oliver Worsley – who died earlier this week after years of suffering from Huntington’s Disease – has revealed that his brain is to be used for research into the illness.

Penelope Worsley, of Heslington, near York, said Oliver, pictured, who struggled in his final years with the lack of independence and the difficulties caused by the devastating disease, had felt very strongly that more research was needed.

“His family decided 24 hours before he died that his brain would be sent to the Brain Bank in London to be used for research into Huntington’s Disease,” she said.

Mrs Worsley said her husband was “known as a true gentleman”. She said: “He was a man who made friends wherever he went; a man who always treated others as if they were special, with a wry sense of humour and a kind and friendly word to all those around him.”

She said he belonged to one of Yorkshire’s “better-known landed families”, growing up at Hovingham Hall with his brothers, Marcus and John, and sister Katherine, who later became the Duchess of Kent.

After going to Eton, he joined the 60th Rifles and was sent to Italy for the last few months of the Second World War.

He farmed at Great Givendale, near Pocklington, and Bishop Wilton, was president of Seaton Ross show for many years and hunted with the Sinnington Hunt and Middleton Hunt. The couple had four children, Georgina, David, Richard and Anne. “He became a director of the Theatre Royal in York, was on the board of Opera North, a director of Tyne Tees Television and Granada Television,” Mrs Worsley said. “He became a patron of the Yorkshire Bach Choir. He took a life long interest in the York City Art Gallery and was president of the Friends for many years.”

She said he set up and ran the Grape Lane Art Gallery, where local artists had the opportunity to show their work.

She said a thanksgiving service would be held at All Saints Church in Hovingham at 2.30pm on Monday, December 13, and all were are welcome.

7:17pm Sunday 5th December 2010

SCARBOROUGH lifeboatmen staged a midnight sea rescue when a crew member of a Fishery Protection Vessel needed medical treatment.

The Jura alerted Humber Coastguard just after midnight on Saturday morning that one of its crew had been taken ill.

Scarborough’s all weather lifeboat Fisherman’s Friend, whose volunteer crew includes an ambulance paramedic, went out to the ship and brought the sick man back to Scarborough Harbour. The fishery protection crew member was then taken to hospital by ambulance.