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Communications Science

Record High Frequency Achieved 141

Posted by ScuttleMonkey
from the music-to-their-ears dept.
eldavojohn writes "Researchers at UCLA Henry Samueli School of Engineering and Applied Science managed to push our control of frequencies to another level when they hit a submillimeter 324 gigahertz frequency. As any signal geek out there might tell you, this is a non-trivial task. '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.' The article also talks about the surprising applications this new technology may evolve into."
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Record High Frequency Achieved

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  • by eln (21727) on Monday April 16, 2007 @11:46AM (#18752073) Homepage
    The article also talks about the surprising applications this new technology may evolve into

    Like making your dog's head explode.
  • Nooo! (Score:5, Funny)

    by Anonymous Coward on Monday April 16, 2007 @11:47AM (#18752075)
    Think of the bees :p
  • How they did it (Score:3, Interesting)

    by $RANDOMLUSER (804576) on Monday April 16, 2007 @11:52AM (#18752157)

    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.
    Sounds like there's room to scale, using this method.
    • Re:How they did it (Score:5, Informative)

      by ToxikFetus (925966) on Monday April 16, 2007 @11:59AM (#18752277)

      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 sounds a lot like a phased-lock loop [wikipedia.org]. And yes, from the article, it appears as though this does have pretty good scalability. TFA said 600 GHz is achievable. 324 GHz a nice because fog is transparent at that frequency.
      • by Anonymous Coward on Monday April 16, 2007 @12:08PM (#18752389)
        "TFA said 600 GHz is achievable. 324 GHz a nice because fog is transparent at that frequency."

        So in twenty years time cars will have an anti-fog display on the windscreen (which will have the ability to switch between transparent and display mode), which will make travelling through fog much safer at high speeds (let's just accept that cars will not have an auto-drive mode by then, eh?).

        On the downside, many crashes will occur because pedestrians on the sidewalk will appear to be naked! Perverts will be making the school run even worse as they hang around outside schools. And we'll all accept it as the price to pay for safety and anti-terrorism requirements.

      • Re: (Score:3, Informative)

        by leighklotz (192300)
        This sounds a lot like a phased-lock loop
        It doesn't sound like a PLL to me; a PLL has VCO in it, and this is a VCO, but the VCO is just the oscillator part.
        I.e., where's the phase comparator?

        It sounds more like a quadrature oscillator with 4 outputs. Oscillators have an inherent need for a 180 degree phase shift, and a quadrature oscillator gives you two outputs 90 degrees out of phase. This one gives you 4 outputs 90 degrees out of phase, which seems a bit of a trick.

        It may be some variant on the Bubba O [google.com]
      • >This sounds a lot like a phased-lock loop.

        There's actually no indication of feedback at all here (which is the whole point of a PLL). In general, actually, feedback slows systems down. They do mention that they are using a VCO -- also used in PLLs -- but I get the impression that the purpose here is to, say, generate frequency modulated radio signals; such a modulator would be an open-loop system.

        • Re: (Score:3, Informative)

          by tlhIngan (30335)

          There's actually no indication of feedback at all here (which is the whole point of a PLL). In general, actually, feedback slows systems down. They do mention that they are using a VCO -- also used in PLLs -- but I get the impression that the purpose here is to, say, generate frequency modulated radio signals; such a modulator would be an open-loop system.

          Perhaps the technique is standard frequency mixing [wikipedia.org], a standard technique used in practically every radio receiver these days. It's basically a three termi

          • Re:How they did it (Score:4, Interesting)

            by TerranFury (726743) on Monday April 16, 2007 @06:49PM (#18759649)

            Perhaps the technique is standard frequency mixing [wikipedia.org], a standard technique used in practically every radio receiver these days.

            Aye, the heterodyne radio receiver. Yeah, I could see them using a mixer! That doesn't mesh with what's described, but, then, (unless I am missing something), what's described doesn't make a ton of sense:
            From TFA:

            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.
            How can any linear system create an output frequency unequal to one of the input frequencies? I could see rectification as providing a frequency doubling -- but that's old, old news, generates horrid output, and is probably not what's referenced here.

            So maybe the article gets it wrong, and you're right?

            If somebody else could shed some light on this, that'd be cool.

      • Re: (Score:3, Interesting)

        A full-wave rectifier works like a frequency doubler, and the article makes it sound like they've extended that to get a frequency quadrupler.

        One significant point here is that the FCC only claims jurisdiction up to 300 GHz.
    • Re: (Score:1, Interesting)

      by Anonymous Coward
      You can't generate new frequencies by linearly superposition. This means that all they did was cancel low harmonics of a not-so-sine wave to "see better" some high harmonic. But this high harmonic was already present in each individual oscillator, so one could say that the frequency was already "achieved".
      • Re: (Score:1, Informative)

        by zippthorne (748122)
        Mod parent down. You can indeed do this. They superimposed rectified quarter-phase signals. In fact, it is a pretty common effect that has been known about since at least the invention of the http://en.wikipedia.org/wiki/Rectifier>rectifier.

        Long story short: a full-wave rectified sine wave will have 2x the frequency of the original. Even if the original is a PURE SINE WAVE. The output however is no longer a pure sine wave. You can get a pure sine wave if you have the right filters, but you're goin
        • Re: (Score:2, Insightful)

          by Anonymous Coward

          You can indeed do this.
          No linear combination of terms of the form sin(a*x+b) can give you a term in sin(c*x) with c != a, but feel free to try.

          They superimposed rectified quarter-phase signals
          So that's the not-so-sine wave I was talking about. How about we mod *you* down for misrepresenting a post just so you can tear it apart and appear knowledgeable?
  • by oskay (932940) on Monday April 16, 2007 @11:55AM (#18752199) Homepage
    Precision phase coherent control of lasers has become possible in the last ten years- Laser beams at frequencies exceeding 1 PHz (10^15 Hz) have been precisely controlled, phase locked, and tuned to have frequencies that are *exact multiples* of our best microwave frequency standards (e.g, cesium). It works the other way too-- our most precise microwave-frequency signals come from divided-down optical frequency references now! See also: 2005 nobel in physics.
    • by niro5 (1081199) on Monday April 16, 2007 @12:12PM (#18752433)
      I agree, my girlfriend reached a far greater frequency when she found a spider in the bath tub. Old news.
    • by insignificant1 (872511) on Monday April 16, 2007 @12:16PM (#18752485)
      Yes, people have achieved higher frequencies, and controlled them very precisely, as you point out; however, such oscillators aren't CMOS oscillators. That's the news, that they've built a CMOS oscillator at such a frequency, not that they have achieved the highest frequency ever to be controlled (which would be a joke). Not exactly what the /. headline implies, though.
    • Re: (Score:3, Informative)

      by jcorno (889560)
      That's an optical frequency. Well, UV, but still, totally different from what they're talking about. Your example has to do with electronic states of matter. They're talking about circuitry.
      • by oskay (932940) on Monday April 16, 2007 @12:40PM (#18752799) Homepage
        The work with the CMOS circuits is clearly an important achievement.

        However, both the Slashdot title ("Record High Frequency Achieved") and summary ("...managed to push our control of frequencies to another level ...") do seem imply that frequency control has not been possible at frequencies that high before. So, it's important to point out that while it's a record, it's only a record within context. (Records within context are fun; you can do anything with them. For example, I hold the bicycle land speed record for all persons with my SSN.)

        In any case, it's *not* totally different. Both are examples of frequency control, which is it's own discipline that spans precision timing and applications in all frequency ranges, from RF (on chips and in free space) to optical (on chips, in fibers, and in free space) and beyond.

  • by lelitsch (31136) on Monday April 16, 2007 @11:55AM (#18752203)
    More than 15 years ago, quite a few of the students at the physics lab I was teaching had their oscillating circuits reach 483 terahertz and more pretty easily. For a short amount of time that is.
  • by LaughingCoder (914424) on Monday April 16, 2007 @12:01PM (#18752299)
    ... how they are able to visualize such high frequencies. How do they know they succeeded?
    • by MrP-(at work) (839979) on Monday April 16, 2007 @12:16PM (#18752477)
      They got a Vista score of 5, so obviously it's running at 324GHz
    • Re: (Score:3, Insightful)

      by pclminion (145572)
      "High frequencies?" We're not even talking terahertz here. The frequency of VISIBLE LIGHT is about a million times higher. This frequency is "high" in the sense that it is one of the highest frequencies ever achieved with an oscillating circuit. It's nowhere near the highest frequencies humans have ever produced or measured. So how do they "visualize" these frequencies? Probably with the same techniques they use to visualize frequencies trillions of times higher?
    • by m0nstr42 (914269)

      .. how they are able to visualize such high frequencies. How do they know they succeeded?

      As mentioned in one of the other replies, there are lots of measurement devices for very high frequency stuff. I'm sure they used something far more precise than this, but here's a couple relatively simple ways to measure a signal that you can't capture on a scope: - use a frequency counter to count the number of zero crossings against a known, calibrated, time-base - use a signal multiplier to multiply by a lower-fr

  • by Lord Bitman (95493) on Monday April 16, 2007 @12:03PM (#18752325) Homepage
    They found frequencies... they didn't even know existed?!

    +1 funny
    -8 bad movie
    -9000 overrated
  • Check out http://www.arrl.org/qst/worldabove/dxrecords.html [arrl.org] for the Amateur Radio DX records. This was achieved long ago and at higher frequencies. Highest RF frequency used for a confirmed two-way communication was 403 GHz between WA1ZMS/4 (FM07ji) and W4WWQ/4 (FM07ji) on 21-Dec-2004 over a distance of 1.42 kilometers. Achieving a frequency is one thing but being able to use it is another.
    • I can't help but think there's a world of difference between how DX stations work and how these CMOS chips work, but I don't think I'll have the time to figure it out before someone more versed in the topics can give a brief rundown.

      One thing that sticks out is that this CMOS variation seems to allow for finely tuned control of the frequency, which allows them to use it regularly and reliably, but I could be way off.
      • by fotbr (855184)
        RF Communication generally needs stable waveforms to be carriers. So no, the end result between a "dx station" and these cmos chips wouldn't really be all that different -- stable waveforms at high frequencies.
    • Re: (Score:2, Redundant)

      I'll post this again: The news is not that they've built an oscillator at the highest frequency ever (think: LASER is much higher frequency); the news is that it's the highest-frequency CMOS oscillator built to date. (Which I can't confirm, but it sounds right to me.)
  • T-rays (Score:4, Informative)

    by kebes (861706) on Monday April 16, 2007 @12:16PM (#18752481) Journal
    This technology is another step along to road to widespread technology exploiting Terahertz radiation [wikipedia.org], which is the region of the EM-spectrum between IR and microwaves. Near the end of the article, they mention the possibility of creating imaging systems that can, for example, see through clothes. These applications of so-called T-rays have in fact already been demonstrated. For example, the image in this article [thznetwork.org] shows a man concealing a knife, which is easily visible in the T-ray image. (See also some other pictures here [thznetwork.org].) T-rays reflect strongly off of metals but can penetrate to varying extents through things like clothing and tissue. The military and security applications are obvious. However it would also bring up new kinds of medical imaging, and has been investigated for quality control, too (for example, scanning the inside of foods in assembly lines, etc.). In the previous link I put, there is an example of scanning through a Hershey bar, where you can see the positions of the nuts.

    Suffice it to say this is an area of active research that may have many, many applications.
  • If aliens are calling then they'd probably be using frequencies along those lines. The logic would be that if they found using such frequencies to be technologically challenging to use why would they bother to communicate with an abundance of lesser civilizations when they could potentially benefit from communicating with equal or superior civilizations across the cosmos?
  • That's nothing (Score:3, Insightful)

    by Koyaanisqatsi (581196) on Monday April 16, 2007 @12:24PM (#18752571)
    My flashlight achieves orders of magnitude higher frequencies in a snap!
    • and you know what, I've done even better. I can generate a pure sine carrier with an infinite frequency: It's a generator that generates 0V DC. Beat that!
    • by dougmc (70836)

      My flashlight achieves orders of magnitude higher frequencies in a snap!

      Hell -- my body emits radiation that's orders of magnitudes higher. Not as high as your flashlight (at least not in any significant amount) but still much higher. I haven't found an effective way to modulate it at a high rate of speed, however.

      The remote for my TV also uses frequencies orders of magnitude higher than those in this article. And it even modulates the signal! Perhaps they should not think quite so much about electronics, and think more about optics ...

  • Didn't they create and usefully apply terahertz frequencies four years ago? Terahertz > 190 gigahertz, right? What's the big deal?

    http://slashdot.org/article.pl?sid=03/02/11/184824 7 [slashdot.org]
    • by Alioth (221270)
      The big deal was that it was done by a CMOS oscillator, i.e. something that can be fabbed in today's semiconductor factories in mass, not something that's limited to the laboratory.
  • *buys a lot of red tape*

    it keeps them out you know
  • My late dog, Rover (may he rest in peace), had his head explode when my sister put on a Mariah Carey CD.
  • I had thought the article would be about a breakthrough in Slashdotter's wanking techniques...
  • "submillimeter" (Score:3, Interesting)

    by ebcdic (39948) on Monday April 16, 2007 @01:14PM (#18753281)
    Sincer "submillimeter" implies a frequency greater than 300GHz, it makes no sense to talk about "usable submillimeter signals with a frequency higher than about 190 GHz".
  • "Because the wavelength is submillimeter, you may image through people's clothing,"


    Another menacing blow to the psyche of cutoff-loving never-nudes everywhere. Time to buy plastic underwear.
  • The size of the circuits and ability to penetrate materials makes this technology part of a future Tricoder type device.
  • by MetaDFF (944558) on Monday April 16, 2007 @01:34PM (#18753601)
    What they did sounds like an extension of the technique used in push-push oscillators to "double" the oscillation frequency.

    The basic principle behind a push-push oscillator is that two out-of-phase signals of fundamental frequency f_o are combined such that the fundamental signal and the odd harmonics cancel, while the second harmonic at 2*f_o add constructively. In the case of a push-push oscillator, you only need two signals 180 degrees out of phase. This could be generated with a differential VCO.

    Using a push-push oscillator is a well known technique for increasing the frequency of oscillation of a VCO beyond the fMAX of a transistors at a given process node.

    The only disadvantage with push-push oscillators is that you end up losing a lot of power as the second harmonics's power will always be much smaller than the power in the fundamental frequency of the VCO.
  • These higher frequencies are pissing off all the stealth flying saucers in the area. They use the frequencies that humans don't use, but their range gets smaller and smaller as we move up the spectrum. They will retaliate with more ubductions and anal probes. You've been warned.
  • new clothes (Score:2, Funny)

    by mekane8 (729358)
    So will we now start seeing tinfoil underwear to go with the hats?
  • This is going to be a problem for quarter-wave diapole fabrication.
  • Big deal (Score:4, Funny)

    by Quiet_Desperation (858215) on Monday April 16, 2007 @02:43PM (#18754599)

    I can create an even higher frequency for a fraction of the cost.

    (Turns on flashlight)

    I can even send information.

    (Blinks flashlight)

    I admit the data capactity needs work, though.

  • No one over 40 will be able to hear it anyway.

    I guess it could be a new Ring Tone.
    • by dougmc (70836)

      No one over 40 will be able to hear it anyway.

      Considering that it's electromagnetic waves rather than sound waves, nobody under 40 will be able to hear it either. Not with their ears, anyways.

      And the `Mosquito' that you're alluding to isn't so imperceptible to adults as people would lead you to believe. I have no trouble hearing it, and I'm only 38. I don't think that two years will make the difference ...

      I guess it could be a new Ring Tone.

      Perhaps for Bender ...

      In any event, at a high enoug

  • Light? Sound? Processor cycles? Faps?

    If it's Faps then that must have been some mighty bad chaps they had at the end... Either that or they were able to invent some extremely low friction lube...

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