. 24/7 Space News .
Engineers Set New World Record In Generation Of High-Frequency Submillimeter Waves

"When you go back to the fundamental math and physics, you find that you can do this and not pay much of a price. That's the beauty of it," Chang said. "If you use digital signal processing, you can synthesize this and synthesize that, but you pay the price for it with a loss of energy."
by Staff Writers
Los Angeles CA (SPX) Apr 17, 2007
Researchers at the UCLA Henry Samueli School of Engineering and Applied Science have achieved a new world record in high-frequency submillimeter waves. The record-setting 324-gigahertz frequency was accomplished using a voltage-controlled oscillator in a 90-nanometer complementary metal-oxide semiconductor (CMOS) integrated circuit, a technology used in chips such as microprocessors.

The signal generator, which produces frequencies nearly 70 percent faster than other CMOS oscillators, paves the way for a new generation of submillimeter devices that could someday be used in high-resolution sensors on spacecraft, and here on Earth in a new class of highly integrated and lightweight imagers that could literally cut through fog and see through clothing fabrics.

And because frequency ultimately means bandwidth, "the higher frequency increases the available bandwidth," said M.C. Frank Chang, UCLA professor of electrical engineering, who leads the research team. That greater bandwidth translates into faster communication speeds.

With traditional 90-nanometer CMOS circuit approaches, it is virtually impossible to generate usable submillimeter signals with a frequency higher than about 190 GHz. That's because conventional oscillator circuits are nonlinear systems in which increases in frequency are accompanied by a corresponding loss in gain or efficiency and an increase in noise, making them unsuitable for practical applications.

Chang, who also is director of UCLA Engineering's High Speed Electronics Laboratory, and researchers Daquan Huang and Tim LaRocca skirted the issues using a technological sleight of hand - and some unique analog signal processing.

The researchers first generated a voltage-controlled CMOS oscillator, or CMOS VCO, operating at a fundamental frequency of 81GHz with phase-shifted outputs at 0, 90, 180 and 270 degrees, respectively. By linearly superimposing these four (or quadruple) rectified phase-shifted outputs in real time, they ultimately generated a waveform with a resultant oscillation frequency that is four times the fundamental frequency, or 324 GHz. This new frequency generation method, in principle, has high DC-to-RF conversion efficiency (up to 8 percent) and has low phase noise, comparable to that of the constituent fundamental oscillation signal.

"When you go back to the fundamental math and physics, you find that you can do this and not pay much of a price. That's the beauty of it," Chang said. "If you use digital signal processing, you can synthesize this and synthesize that, but you pay the price for it with a loss of energy."

The measurement test of the 324-GHz signal was conducted by engineers Lorene Samoska and Andy Fung of NASA's Jet Propulsion Laboratory in Pasadena, which has facilities to test these high-frequency ranges. JPL and NASA are particularly interested in submillimeter technology because submillimeter-range wavelengths are ideal for deep-space remote sensing - there is no atmosphere in space to dampen the signals. Higher frequency signals, in turn, produce higher resolution images. "You can see better," Chang said.

Chang and Huang, in collaboration with JPL colleagues, have jointly applied for government grants to use the technology to design lightweight, low-power and highly integrated signal generators that can produce signals at frequencies up to 600 GHz. Applications for these high-frequency VCOs include imaging systems for both commercial and future space missions.

Creating 600-GHz signals requires a relatively straightforward modification of the circuit - either by increasing the fundamental frequency of the VCO or increasing the number of superimposed oscillator outputs (using eight or 16 instead of four).

"Because the algorithm has been validated, we know that we can achieve these frequencies," Chang says.

For example, if quadruple 85-GHz VCO outputs are used, the resulting output frequency would be 340 GHz. That frequency is something of a Holy Grail to the commercial aerospace industry and the military because it represents a "window" in our atmosphere where there is very little attenuation of submillimeter signals. (Essentially, they are invisible to the air.)

Normally, millimeter-range waves excite the atomic and molecular bonds in water, oxygen, carbon dioxide and other molecules in the atmosphere, and the gases absorb the waves. Signals at 340 GHz, however, "sneak through," Chang said, and can propagate long distances.

"One result is that waves of these frequencies can see through the fog, which is of interest to commercial aerospace companies," he said. Chang estimates that he and his colleagues will be able to produce the 340-GHz signals within the next six months

Another application of the high-frequency CMOS VCOs of interest to the United States military is in submillimeter wavelength imaging. "Because the wavelength is submillimeter, you may image through people's clothing," Chang said. "For example, it would be possible to remotely view if some civilian walking up to you has plastic explosives hidden under his coat."

CMOS technology makes future submillimeter-wave devices easily integrated with advanced microprocessors on-chip and can be very lightweight, so these sensors would be portable. "Foot soldiers could backpack them into the battle zone," Chang said.

Email This Article

Related Links
University of California - Los Angeles
Powering The World in the 21st Century at Energy-Daily.com
Our Polluted World and Cleaning It Up
China News From SinoDaily.com
Global Trade News
The Economy
All About Solar Energy at SolarDaily.com
Civil Nuclear Energy Science, Technology and News



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


Mass Weddings Leads To New Efficient 2-Photon Source
Washington DC (SPX) Apr 17, 2007
For a variety of applications in physics and technology, ranging from quantum information theory to telecommunications, it's handy to have access to pairs of photons created simultaneously, with a chosen energy.







  • Merlin Secures NASA SEWP IV Contract With Potential Value Of Over USD 5 Billion
  • Bill Gates Eyes Flight To Space
  • Latest Space Tourist Docks At Space Station For Week Long Holiday
  • Fifth Space Tourist Soars Toward Space Station Holiday In Space

  • Through A Telescope Darkly
  • Report Reveals Likely Causes Of Mars Spacecraft Loss
  • Mars Project To Simulate Radiation Exposure
  • Experiment Simulates Radiation Exposure

  • Indian Space Agency Set For First Commercial Launch Of Foreign Satellite
  • Russia To Launch Four US Satellites In May
  • PSLV-C8 To Be Launched On April 23
  • ILS Proton Successfully Launches Anik F3 Satellite

  • US Uses Landsat Satellite Data To Fight Hunger And Poverty
  • NOAA And NASA Restore Climate Sensor To Upcoming NPP Satellite
  • High-Resolution Images Herald New Era In Earth Sciences
  • ISRO To Focus On Societal Projects

  • Rosetta And New Horizons Watch Jupiter In Joint Campaign
  • New Horizons Shows Off Its Color Camera In Io Image
  • Alice Views Jupiter And Io
  • A Look From LEISA

  • Hotter Than Expected Neutron Star Surfaces Help Explain Superburst Frequency
  • Featherweight Celestial Pair Has Uncertain Future Together
  • Mystery Spiral Arms Explained
  • Key Stardust Spacecraft Find Questioned

  • Shanghai Vies To Win Battle Of Moon Rovers
  • A Piggyback Solution For Science Versus Exploration
  • Assembling Of Moon Mission Spacecraft Begins
  • Dust-Busting Lunar Style

  • China Launches Compass Navigation Satellite
  • Northrop Grumman Team OCX Bids On The GPS Next Generation Control Segment Contract
  • GPS Significantly Impacted By Powerful Solar Radio Burst
  • Russia To Expand Glonass Satellite Group By Year End

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement