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Power Hardware

Breakthrough Promises Smartphones that Use Half the Power 110

Posted by samzenpus
from the save-the-juice dept.
Dupple writes in with news about a discovery that should extend the life of your battery in the near future. "Powering cellular base stations around the world will cost $36 billion this year—chewing through nearly 1 percent of all global electricity production. Much of this is wasted by a grossly inefficient piece of hardware: the power amplifier, a gadget that turns electricity into radio signals. The versions of amplifiers within smartphones suffer similar problems. If you've noticed your phone getting warm and rapidly draining the battery when streaming video or sending large files, blame the power amplifiers. As with the versions in base stations, these chips waste more than 65 percent of their energy—and that's why you sometimes need to charge your phone twice a day. It's currently a lab-bench technology, but if it proves itself in commercialization, which is expected to start in 2013—first targeting LTE base stations—the technology could slash base station energy use by half. Likewise, a chip-scale version of the technology, still in development, could double the battery life of smartphones."
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Breakthrough Promises Smartphones that Use Half the Power

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  • Re:Nah. (Score:5, Informative)

    by Neil Boekend (1854906) on Thursday November 01, 2012 @03:49AM (#41839485)
    Nope, because it doesn't increase the range of the antenna. The same limits to transmitted power apply, no matter what technology you use to transmit it.
    Besides, in heavily populated area's the number of antennas has nothing to do with transmit power, but with maximum throughput.
  • by Decker-Mage (782424) <jack_of_shadows@yahoo.com> on Thursday November 01, 2012 @04:04AM (#41839541)

    Probably due to the fact that all of IT consumes about 1% of all power globally. And notice in that statistic "about" which, if it comes above 0.0000...01% somehow gets magically gets rounded up (apparently using ceil (APL) function rather than a real rounding function). If they really want to save power generated capacity, they really should look at replacing all those power bricks out there with something remotely efficient before thinking about the power consumption drawn from an, also admittedly, inefficient battery, on the way to the power amps.

    Matters not much, methinks, as no one is going to take advantage of the new designs until (1) they are incorporated into "stock" parts and (2) they are cheaper than the designs they are replacing. Almost forgot, and no one is still running a fire sale on the old chips.

    Articles like these, long on promise, short on economics, or long on threat, and short on the same thing, economics, piss me off.

  • Re:Class C (Score:5, Informative)

    by Gordonjcp (186804) on Thursday November 01, 2012 @06:27AM (#41840155) Homepage

    No, the problem is that they need to be linear. You can use class C for FM (and therefore GMSK) because you're running at full carrier power continuously. For 3G, you need a linear amp because QAM has potentially got a variable carrier level. There are tricks you can do to get round this (envelope restoration) which could be what TFA is on about, but it's slashdotted.

  • Envelope tracking (Score:5, Informative)

    by Iconoc (2646179) on Thursday November 01, 2012 @06:30AM (#41840171)
    What this article never really manages to describe is Envelope Tracking (ET). This has been in development for several years. Look at the diagram in http://www.nujira.com/technology-pa-746.php [nujira.com] for a better description of the concept. This article describes the application of ET in the handset.
  • Re:Class C (Score:5, Informative)

    by smpoole7 (1467717) on Thursday November 01, 2012 @07:57AM (#41840567) Homepage

    > Class C RF power amplifiers can be ~90% efficient, because they drive a tuned load. That's been known for most of the 20th century. Is the problem that these need to be wideband amps?

    You're on the right track, but the answer is a bit complicated. (The article, by the way, sounds like a PR piece for someone expecting to patent a technology that, by the same arguments we use against software patents, probably shouldn't be patentable, because it's an obvious rearrangement of existing technology. I shall elucidate.)

    1. Yes, it's difficult to run wideband amps in class C. Class C works best with a single frequency at a constant level.

    (To illustrate: my wideband HD transmitter, for example, must be re-biased to class AB. I can switch it to "pure" class-C FM mode and it puts out 2-3 times the power as when it's in HD mode.)

    2. As a general rule: designing an efficient amplifier becomes more difficult the higher the frequency. Wireless phones run at high frequencies.

    (To illustrate: class D switching amps have made it possible for your teenage son to have 1,000 watts of audio in his Nissan Sentra. But you must use a switching frequency that's much higher than the signal -- easy to do with audio, not so easy with even just an 800-900 MHz wireless signal.)

    3. Read the fine print and look beyond the smoke.

    We just went with Modulation Dependent Carrier Level (MDCL) on our 50,000 watt AM, and it has indeed cut our power bill substantially, which is strikingly analogous to what these people are proposing. But this is highly dependent on modulation (i.e., what we're "playing" at any given moment, whether music or voice) and other factors.

    In this case, if they're obtaining the higher efficiency by "smoothly" switching between standby and active modes, one wonders how efficient it will be during rush hour, when everyone is on the phone, calling their significant other to have dinner ready when they get home. :)

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