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Student Invention May Significantly Extend Mobile Device Battery Life
imamac writes with this excerpt from news out of Carleton University:
"Atif Shamim, an electronics PhD student at Carleton University, has built a prototype that extends the battery life of portable gadgets such as the iPhone and BlackBerry, by getting rid of all the wires used to connect the electronic circuits with the antenna. ... The invention involves a packaging technique to connect the antenna with the circuits via a wireless connection between a micro-antenna embedded within the circuits on the chip. 'This has not been tried before — that the circuits are connected to the antenna wirelessly. They've been connected through wires and a bunch of other components. That's where the power gets lost,' Mr. Shamim said."
The story's headline claims the breakthrough can extend battery life by up to 12 times, but that seems to be a misinterpretation of Shamim's claim that his method reduces the power required to operate the antenna by a factor of about 12; 3.3 mW down from 38 mW. The research paper (PDF) is available at the Microwave Journal. imamac adds, "Unlike many of the breakthroughs we read about here and elsewhere, this seems like it has a very high probability of market acceptance and actual implementation."
Wow, is it me or does it feel profoundly counter-intuitive that you'd lose more power over the wire than over radio waves?
You just got troll'd!
I like the idea of using my iPhone for days at a time between charges. Heck, maybe would provide enough battery for a useful iPhone/GPS unit.
I think this joker hit the '+' button when he meant to hit the '-' button. 12 times. I don't think so.
...until you consider the security ramifications.
The explanation given on the website is very poor. The resistance of the wires connecting the transceiver and the antenna is low and little power is lost in them.
In addition, they quote him as saying "There are so many applications in the iPhone, itâ(TM)s like a power-sucking machine" but what they're talking about is the power lost at the antenna and not from the processor which is what he implies. Therefore it wouldn't do anything to prolong battery life when using non-transmitting applications.
Perhaps this is a case of announcing something without giving away what it really is or perhaps pathetic technology journalism?
What's the win here? He's capacitively coupling the transmitter to its antenna, or what?
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
There definitely needs to be more research on Battery life....it's advancing slower than the gadgets which causes a ceiling on innovations!
I mean my phone lasts for days if i don't use it and many hours if i'm just talking. The vast majority of power seems to be used when I'm watching video, playing games, or browsing the web. My guess would be this is more CPU related.
So even if it saves 10x in the transmit/receive it still might only be a 2x overall savings or less. I suppose it depends on usage patterns.
Last line of the pdf:
The conventional LTCC package provides 3 times more range than the proposed design but consumes 12 times more power.
(only a software engineer) ... but when you tell me that replacing copper wires with a (wireless) transmitter and receiver helps save power: well I am a non-believer. Sorry. Just does not cut it whatever the headlines say. How about quality ?
If the circuite powering the antenna was the greatest consumer of power in the device, this would result in a significant improvement to the end-user. However, it's all the other bits in the device which eat thousands of times more power -- the CPU, the display, the speakers, etc.
Interesting discovery, but the real-world savings will be few.
Goes double for WiFi, which is an extremely chatty protocol and thus sucks power. Could make WiFi much more usable in smartphones. Right now, if you play with WiFi much, you'll find that your battery gets drained fast as compared to EVDO or the like.
"This configuration isn't uncommon and many microwave systems employ this technique. (Attaching the amplifier nearly directly to the antenna.)"
I agree, it sounds very much like some kind of Impedance Matching technique where the Inductive coupling is direct to the antenna. I'm not so sure that's as patentable as this University is drumming it up to sound. (I guess they hope to earn a lot of money from it, mainly from from phone companies). But Impedance Matching using windings to effectively wireless couple to the antenna (where the antenna acts like part of the winding) isn't something new. If anything its something very old.
This article is sounding like bad marketing but my guess is having no physical connection means the antenna is isolated completely, and the lack of nearby circuitry reduces the noise floor on what it sends and receives, reducing the necessary power to send a clear signal.
He mentions "other parts" being part of the existing antenna connection... what would those be?
From the research paper:
So you save power versus the conventional design, but you lose range.
To provide the same signal strength at triple the range, you need to broadcast 9 times as much power. To broadcast 9 times as much power with an equally compact transmitter, is it surprising that you need to spend 12 times as much power due to size/efficiency trade-offs?
This doesn't sound like an advance at all.
I can tune a pringles can to broadcast 10 miles on a standard (2.4Ghz, 802.11B/G) wireless router. If it is the SLIGHTEST out of tune, i cant even get a mile. Why not tune a cell antenna? I know for a fact that they didn't even try in my Razr.
I don't think this will "significantly extend" mobile device battery life, As other people have pointed out, something that could practically save maybe 10mW of battery power during transmit operation is interesting but not really all that dramatic. On the other hand, the author doesn't appear to make the claim that it will or won't significantly extend battery life. That may be a slashdottism :)
If I understood the abstract right, the gist of this is that he designed a transmit module with a small internal loop antenna, so that a larger transmit antenna could be inductively coupled instead of electrically driven. This means that all of the bias and driver circuitry internal to the transmit chip and also all of the bias and transmit circuitry external to the chip could be done away with. He coupled an antenna to the outside of a microchip to utilized what would essentially be 'waste' magnetic field in a conventional transmitter.
I would also bet that the big boys like Qualcomm probably do something similar already inside of their cell-phone modules. I would imagine that an approach like this eliminates much of the general purpose interfacing that needs to be done between some arbitrary microwave transmit module and some other arbitrary antenna, but things like cellphone transmitter chipsets are so tightly integrated that I bet they already implement something similar.
---- I'll take you in a Hunt deathmatch any day.
Not true.
Wired mics sound better because they lack the companders involved in transmitting the audio signal. Performers like wireless because it's convenient, not because it sounds better. Those concerned with sound quality stick to wired.
Balance signals use common mode rejection to eliminate induced noise. This has been standard practice for years. Recording studios used either balanced wiring, or digital in the form of AES or optical ADAT.
No matter how you transmit the power, you still have to drive the gate capacitance and that takes a little bit of power. My hunch is that the writer didn't understand anything they guy said and was just winging it to the publics detriment.
You can dissipate power by radiating when you don't want to - may ways around this.
This idea is pretty useless, since it have been confirmed that cellular companies do not truthfully report the amount of battery life left, so people will make shorter calls and not take up the valuable bandwidth of theirs that they oversold.....
Knowing Google's lust for data collection, the Soviet Union is still alive and well inside the psyche of Sergey Brin....
I remember back when we used to have wires going all over the place to connect everything. Then they invented wireless connections and everything had to be plugged in to rechargers and we had wires going all over the place. Then they invented wireless charging bases for all our wireless devices and we had wires going all over the place. Then they invented...
Ph.d candidate... is factual and much less sensationalized.
Here's the idea:
Generally speaking you generate the signal (using an oscillator) then run it through an amplifier and filter before it goes through the antenna. Each of those stages consume power. The amplifier has an efficiency which means you get less power out in the signal than you put into the amplifier for operation, and the filter has loss.
The idea here is that the signal generation using the VCO (voltage controlled oscillator) is combined with the filtering and the antenna, in essence, as "one step".
However this is going to have a very narrow range of application. There are many reasons why a VCO needs buffering and isolation from the outside world. There are many cases, especially for complex modulation, where coupling the VCO like this more closely to the outside world will degrade it's performance (yes, even if you are using a PLL) to an extent that you wouldn't be able to make a working radio with it.
So for certain low power, low complexity applications this does help, but for anything which needs a "real" radio it won't do much good. It's really more of a packaging gee-whiz.
Absolute statements are never true
The loss of energy in a co-ax cable is well known. It is usually measured in dB per 100 feet. Bad cable at 2 GHz might be 100 dB per 100 feet. I leave it to you as an exercise to figure out the loss of two inches of cable.
Belden RG-174 has about .6dB loss/ft @ 5.6GHz
http://www.belden.com/pdfs/TechInfo/Coax%20Electrical%20Characteristics.pdf
http://www.belden.com/pdfs/03Belden_Master_Catalog/06Coaxial_Cables/06.59_66.pdf
In GOD we trust, all others we monitor.
Actually, a Tesla coil works on very similar principles, and the power coupling in them is very efficient.
A waveguide is far more efficient of a transmission line than coax or any other wireline can hope to achieve. If he's found a way to build a waveguide (or reasonable fascimile thereof) by clever geometry, it could be very efficient.
"Yo dawg, we heard you like wireless so we put a wireless antenna in your wireless device so you can be wireless while you're wireless!"
So I herd you like antennas so we put an antenna to your antenna so you can phone while you phone
Although I'm doubtful that this invention would actually save 34.7mW, I was curious to see how much extra battery life this would actually give me.
My Nokia 2630 has a 700mAh 3.7V battery and is rated for 6 hours of talk time. Based on these numbers, the phone consumes 431.7mW. With the power reduction described, this would result in 397mW of power consumption, yielding 6.52 hours of talk time. Thus, an 8.7% increase in battery life.
As I said, I am pretty skeptical of a 34.7mW power savings; research papers often leave out the negative details.
Electrical engineering involves an intricate set of tradeoffs. When choosing how to couple two transmitter stages there are at least six basic ways to do it: Direct, capacitive, single-tuned, double-tuned, critcally coupled, overcoupled, tapped, T-section, balun, and many more. The one you choose depends on a lot of factors, efficiency, power level, bandwidth, phase linearity, space, shielding, cost, parts availability, reliability, feedback, adjustability, temperature stability, and more.
Seeing as there are all these methods and criteria, it's just not possible that there is one "new" scheme that is better in every category than the 80 years supply of coupling schemes.
In particular, a "wireless" method is going to lose on efficiency-- it's not going to be more than 5% efficient. So you would not use it coupling to a medium or high power stage.
And there are other severe gotchas, like susceptibility to feedback and EMI.
There may be certain niches where one would chose this method, but it's unlikely to be a major player, especially since all the other methods are parent-free.
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