Reduce Transistor Power Consumption 124
revelCyllufyalP writes to tell us that University of Kentucky researchers have discovered a way to reduce the overall power consumption of transistors. From the article: "In order to improve computer chips' performance, transistors' size and gate insulators have to be continuously shrunken so that more components can be packed into a single chip. Computer chip producers were hitting a wall in downscaling the transistors and gate insulators because of their inability to reduce the leakage current of the existing gate insulators. This new technique will help the chip producers to develop more powerful chips with low-power consumption."
Woohoo (Score:4, Interesting)
Re:Woohoo (Score:3, Informative)
Re:Woohoo (Score:1)
Re:Woohoo (Score:2)
Re:Woohoo (Score:1)
First - other than the digital parts of the device usually BJTs are used which have a leaky base as it is so improving the MOSFETs will not do anything for the BJT parts of the circuit.
Second - even if you make the whole device with MOSFETs the real power consumption is in parts like the transmitter and receiver which have orders of magnitude more current going through them than the leakage current.
Third - most wireless devices
Yeah (unsupported claim) (Score:1)
As an aside, I'm reminded of the joke which is probably rewritten for numerous groups.
A person on the Indiana side of the Ohio river tells a person on the Kentucky side that he will shine a flashlight across the river and he can walk across the beam. The person on the other side says, "No way! You'll shut the flashlight off w
Re:Yeah (unsupported claim) (Score:1)
"some folk'll never eat a skunk, then again some folk'll"
How do you reduce tunneling current? (Score:5, Interesting)
Re:How do you reduce tunneling current? (Score:2)
Re:How do you reduce tunneling current? (Score:5, Informative)
It's easy to reduce the tunneling current through the gate. All you have to do is increase the thickness of the insulator. Unfortunately, this has the detrimental effect of reducing the effective capacitance of the gate, which in turn lowers the amount of current conducted by atransistor of a given size (lowering the current also lowers the speed). To make up for the lowered gate capacitance, researchers have been trying to increase the dielectric constant of the insulator. I'm guessing that they're proposing a method to increase the dielectric constant of the gate insulator. The devil is in the details of improving the dielectric constant without screwing up later processing steps or reducing the mechanical integrity of the wafer, etc.
Summary:
Re:How do you reduce tunneling current? (Score:5, Funny)
Hope that clears things up for everyone.
Re:How do you reduce tunneling current? (Score:2)
Re:How do you reduce tunneling current? (Score:2)
Increasing the gate insulator would in turn, perhaps affect the electric field strength required to create or deplete the SourceDrain Tunnel - which in turn, requires more current -> higher power consumption.
So these guys found a way to reduce leakage current without increasing the insulator size...?
Or Am I getting this wrong?
Re:How do you reduce tunneling current? (Score:2)
The process these gentleman describe involves s
Re:How do you reduce tunneling current? (Score:1)
Re:How do you reduce tunneling current? (Score:2)
Re:How do you reduce tunneling current? (Score:1)
Isn't it something like the increased capacitance causes a greater charge to accumulate which enhances the depletion region thus increasing the conductivity of the silicon?
Re:How do you reduce tunneling current? (Score:2)
Re:How do you reduce tunneling current? (Score:1)
Re:How do you reduce tunneling current? (Score:1)
Physics (Score:5, Informative)
A quick lesson in quantum physics:
Basically, tunnelling occurs because an electron can get from one side of a potential barrier to the other without ever being in the forbidden region (the width of the barrier, where the potential energy exceeds the total energy of the electron) due to it existing as a wavefunction that does not collapse until you observe it. Anyway, the chance of an electron penetrating a simple potential barrier like the gate of a transistor is a function of the height of the barrier (voltage applied to the gate), the width of the barrier (gate length), and the energy of the electron (voltage across transistor + electron thermal energy).
So ways to decrease tunnelling include:
Just my $0.02 since if I knew for sure I'd be making 6 figures somewhere and not applying to grad schools...
Almost right. (Score:1)
Also, the height of the barr
Re:Physics (Score:1)
Something I'm a bit surprised that no one has mentioned yet is the capacitance of the p-n junctions in the transistor. Don't forget changing the dielectric constant and the potential has an effect on this aspect of the component as well. To people asking "how important is such a capacitance?" Well, the capacitance causes frequency dependent behavior (you have just introduced an RC time constant).
An area where I have dealt with thi
I saw this presented at ISDRS today... (Score:1)
Re:I saw this presented at ISDRS today... (Score:1)
What does this mean? (Score:1)
Re:What does this mean? (Score:1)
Re:What does this mean? (Score:3, Insightful)
the real killer in microprocessors is the dynamic power - for wireless/dsp/ucontroller type applications, it could be pretty huge
honestly, the article has so few details it's impossible to tell what they're really doing, but i am pretty sure that most companies out there already use RTP on there gate oxide...
Re:What does this mean? (Score:2)
Re:On on U of K... (Score:1)
Re:On on U of K... (Score:1)
Re:On on U of K... (Score:1)
Re:On on U of K... (Score:3, Insightful)
Re:On on U of K... (Score:1)
Prior art? (Score:5, Funny)
Where's the news? (Score:5, Interesting)
lamps, heat the wafer to >1000C for a very brief time, grow a few atomic layers of silicon dioxide (or some variant that includes nitrogen), turn off lamps, cool wafer, take it out of chamber.
From what little info is in the press release, it doesn't sound like they're doing anything revolutionary, so I'm curious why they claim they can reduce gate leakage by so much.
Re:Where's the news? (Score:2)
It is already done, old news (Score:4, Interesting)
Re:It is already done, old news (Score:2)
Sure. The new is how this: It's a press release! Whee! Your life will never be the same!
Cuts 75% of power usage in current generation (Score:5, Insightful)
What this really means is that the next generation has just become possible. As an incidental side benefit, current-generation laptops will be able to run cooler.
Re:Cuts 75% of power usage in current generation (Score:1)
Re:Cuts 75% of power usage in current generation (Score:2)
Re:Cuts 75% of power usage in current generation (Score:4, Informative)
Re:Cuts 75% of power usage in current generation (Score:2)
Re:Cuts 75% of power usage in current generation (Score:1)
It's all well and good in a research lab, but a lot has to happen before this
mystery technology gets rolled out into a mainstream fab. Not knowing much about
it (the linked article was really uninformative) you would have to look at how
much equipment is necessary for these extra steps, how many more steps does it
add to the wafer fab process, what immediate yield impact it has, and are there
any long term effects, does it impact the design rules you work unde
Re:Cuts 75% of power usage in current generation (Score:1)
Must be late... (Score:3, Funny)
Re:Must be late... (Score:2)
We had to change the title quick like after the truth was printed.
Cant have that getting out.
Your sig: (Score:2)
Re:Your sig: (Score:2)
Re:Your sig: (Score:2)
Ouch! What the GP was mentioning with twins though, is that your sig "Human being (n.): A genetically human, genetically distinct, functioning organism." (emphisis mine)
... on the other hand perhaps we can look at it as a "Human B
According to that definition, maternal twins (triplets, etc) would not qualify as a Human Being since each one is not genetically distinct
Re:Your sig: (Score:2)
With regard to normal twins, I agree that the language doesn't parse nicely. I'm not intending "distinct" to mean "unique", but simply "distinct from other organisms which might be present and attached." S
Re:Your sig: (Score:2)
Re:Must be late... (Score:2)
I'm not sure that's the best potential application for their tunneling system.
size vs heat (Score:5, Informative)
CMOS is based around two transistors, a P-channel FET which goes conductive when the gate is driven low, and an N-channel FET which goes conductive when the gate is driven high. The P-FET is trying to pull the output high and the N-FET is trying to pull it low. Both the gates are joined together, and this is the input. This is a simple NOT gate.
For a NAND gate, where any input 0 will drive the output to a 1, we have several P-FETs in parallel trying to drive the output high, and so many N-FETs in series trying to drive the output low. Each P-FET gate joined to an N-FET gate is one input. When they are all high, all the N-FETs turn on allowing the output to go low; when any one is low, the chain of N-FETs is broken, one or more P-FETs turn on, and the output goes high. For a NOR gate, where any input 1 will drive the output to a 0, we put the Ns in parallel and the Ps in series. You can make AND gates from NAND+NOT, OR gates from NOR+NOT, and any other combination you like. In fact you really don't need both NAND and NOR, because you can make either one out of the other; but it turns out they're equally as easy to make as each other in CMOS {not like many other technologies}.
In an ideal world this would never dissipate any power, since the input cannot be high and low at the same time so only one of the transistors will ever be on. In practice what happens is that the gates act like capacitors which take a finite time to charge and discharge. They do not switch instantaneously from conductive to non-conductive. So one stops conducting while the other is starting to conduct, and for a brief instant while the inputs are changing state both transistors are conducting a little. It's not a dead short circuit of course, otherwise something would give way
Now every time something changes state, you get a little pulse of heat. Which is why fast processors need cooling. Additionally, to make sure that the logic gate output has changed state before the next clock pulse, you need to make the gate capacitances charge up quickly -- which means using a higher voltage than you could get away with at lower speeds. But 2x more volts means 2x more amps means 4x more watts.
Smaller transistors should have less gate capacitance, and so be capable of switching more quickly.
Re:size vs heat (Score:5, Interesting)
Some clarifications:
Short-circuit current is only responsible for 10-20% of switching power. The rest is dissipated in the transistor through charging and discharing all the nodal capacitances (due to transistor gates, transistor diffusions and wiring capacitance). Since typical circuit styles are non-adiabatic, this charge/discharge power component would not go away even if we could completely eliminate short-circuit currents.
Making transistors smaller certainly reduces their gate capacitance but it also reduces their current drive by the same proportion. These two effects cancel each other out! So how can transistors get faster from generation to generation?
Transistors get faster by increasing electron mobility and/or increasing gate capacitance per unit area and/or reducing diffusion junction/sidewall capacitance per unit area/perimiter and/or reducing (local) interconnect capacitance since smaller transistors are closer together.
Re:size vs heat (Score:1)
Are you sure? As I remember, let's say we take a transistor and halve every dimension. By C=(8.8542 x 10-12 K A)/D this will halve the capacitance. Now we've halved the conduction channel though, so at constant ohms/square (as is a fair model for most FETs in the conduction region) then the resistance of the channel stays constant. Assuming we keep the same drive voltage this
Re:size vs heat (Score:5, Insightful)
The unfortunate corrolary to: is:
Which is why the P4 prescott, while a marvel on the drawing board, is pretty crappy in reality. 90nm technology has largely been an attempt to find a happy medium between higher capacitance and lower resistance, both of which limit speed. The current "nucular age" of chips is a direct by-product of ignoring the drop in resistance until it was too late.
Also, at 4+ Ghz an current-induced EM field has many of the properties of a microwave beam, which can resonate, and essentially self-focus on any imperfections in the semi-conductor structure, essentially burning small holes in the chip, or causing signal noise unless perfectly grounded (which in itself causes inductive leakage). This is why intel and amd have speed-bins, because the chips with the fewest imperfections are able to perform at the highest clockspeeds without thermal or electric failure.
My point is, the mega-hurts race, even assuming one or more miracles of metal-oxide chemistry, is ending. I look forward to the multi-proccessing race which seems to be heating up, as a long-postponed, but neccessary next step. The sad obstacle holding back the day of 1000-thread chips has been programmers complete lack of willingness to move beyond the single-threaded debugging paradigm. As one myself, I understand why it's seen as hard as it is, but consider it more of a viewpoint shift, rather than an insurmountable increase in complexity. New languages/language changes will happen to simplify threaded programming, and new mechanisms like auto-synchronized data structures, self-unrolling iterands, and integrated message-passing stacks will replace old-standbys. The mega-threading doomsday scenario will fall along the wayside with other past programmer nightmares such as the death of the goto loop and the loss of direct memory access in java and higher level languages, left only as subjects of nostalgia.
Clockspeed is dead, long-live multi-threading.
that is so very not right... (Score:3, Interesting)
Let me explain it a little b
Re:that is so very not right... (Score:3, Interesting)
don't compare specialized chips to general purpose (Score:2)
If you want to run code across a family of processors, you'll have some wastage of transistors. This isn't avoidable. But it is also critical. You can't just make one CPU and throw it away, you need a family to compet
Re:don't compare specialized chips to general purp (Score:2)
I'm not trying to write-off chip speeds, but as a programmer I'm aware we can't just count on the fact that this bloated, single-threaded program/game which slugs around now will work fine 1 year from now when the processors catch up.
Second, multi-chip cpu's do work, the gpu is essentially a graphics slave to the primary, specialized for its tasks, with access to primary memory, and using specialized (tho with need of improvement) mechanisms to offload work from the cpu. TCP offload adapters are
multi-chip CPUs (Score:2)
Let me explain.
It used to be that you might have multiple chips involved directly in the execution of the instruction stream. For example, the AMD 2900 series was bit-sliced. When an instruction was fetched and executed, multiple chips worked on it in parallel. I don't know the restrictions, but I believe each chip operated on 8 bi
Re:that is so very not right... (Score:3)
Strong claim. One must ask: Why?
> That means you have to duplicate every transistor in the chip (like registers) 1000 times.
And this is bad... how?
> That makes no sense.
It makes enormous sense when you're running 1000 threads!
> You will never reach the same speed as current single processor chips with a 1000-thread CPU
> (at least not right now).
Naturlich, since the latter is a figment. But supposing it were real, one would have to as
Re:size vs heat (Score:1)
So true. Nature "figured this out" long ago. For proof, check out the massively parallel machine that is your brain. It would be interesting to make a simple processor that could be tiled ala VLSI and interconnected to its neighbors or a center controller. Massive multi-threading will work best when the hardware matches the software concepts.
Re:size vs heat (Score:3, Interesting)
Even if they don't EVER conduct (even a little) at the same time there will be dissipation because the capacitance is charged and discharged all the time. Each of these cycles implies that some positive charge moves between the power supply and ground with the capacitor as a
How did they do it? (Score:2, Funny)
Chip insulator sas capacitors? (Score:2)
I'm not a chip designer, just a ham radio bug, so I don't know if this problem has already been found to be a non-issue. Maybe one of you bright guys knows the answer?
Re:Chip insulator sas capacitors? (Score:1, Informative)
The leakage is normally due to direct tunneling. Basically the silicon dioxide layer is so thin and the electric field is so high that electrons tunnel between the gate and the source/drain.
I think all this paper is about using some sort of thermal processing to make a higher quality ga
Re:Chip insulator sas capacitors? (Score:2)
MOS transistors have acted like capacitors for ages. There's no power flow in the sense of work done, there is just the regular expense of charging/discharging the gate.
Re:Chip insulator sas capacitors? (Score:3, Informative)
The "work done" is, to some extent, recoverable when you change the state of the MOS transistor by discharging
Re:Chip insulator sas capacitors? (Score:1)
Power "flowing" is a horrid concept. Current flows, power is a measure of work done.
So no a capacitor will do no work (well, capacitors do get hot, but that's the resistive component of their physical construction). If you attatch a perfect capacitor to your AC supply most power meters will register power consumed (after all they're doing V*I) even though the transistor isn't dissapating any heat itself. The point being that the current is out of phase with the vol
WTF is rapid thermal processing? (Score:2, Interesting)
Re:WTF is rapid thermal processing? (Score:1)
They put a french fry in the microwave (Score:1)
PlayfullyClever, eh? (Score:5, Interesting)
Re:PlayfullyClever, eh? (Score:2, Informative)
Re:PlayfullyClever, eh? (Score:2)
-b
Re:PlayfullyClever, eh? (Score:4, Informative)
Now, he might think the joke is that he's posting 'news' from a news aggregation site to a news aggregation site, but meta news is the only kind of news slashdot gets anyway, and that's what we come here for.
All in all, if he's scamming slashdot, he can only be doing it if EurekAlert is a fake, which it certainly doesn't look like at first glance, though I notice that in an unusual move for a meta-news site, it doesn't have links to originating information. That is somewhat suspicious. Still, if true, it's an incredible effort he's putting in just to scam slashdot stories.
Further, it would have to be a long term scam plan, since the UKY story in particular is real:
http://news.uky.edu/news/display_article.php?arti
So at best he's trying to build credibility as an article submitter for a later scam.
Re:PlayfullyClever, eh? (Score:1)
He submitted the story until you view it, at which point, he didn't.
Other Applications (Score:3, Insightful)
Making a CPU fan that lasts more than a year... (Score:2)
Let's not even discuss my underengineered AOpen laptop with its hopelessly inefficient (and now defunct) fan, other than to say that bypassing 75% of its heat generation would be -ing marvellous; the hard disks might also last more than a year, and the battery be worth something again (maybe wi
Re:Making a CPU fan that lasts more than a year... (Score:2)
"University of Kentucky researchers" (Score:1, Flamebait)
That's Gate Leakage, but what about SD Leakage? (Score:2, Interesting)
This just tells us that future technologies are not going to have twice the leakage power as current technologies. This doesn't mean that future process technologies are going to have less leakage pow
Kentucky, kentucky... (Score:1)
*ducks*
bigger processors? (Score:1)
Re:bigger processors? (Score:2)
Re:bigger processors? (Score:1)
Re:bigger processors? (Score:1)
Re:bigger processors? (Score:1)
The UK researcher's secret technique: (Score:1)
We all know that the fab process for turning silicon into chips is *way* too complex to be explained by ordinary science, so the UK researchers instead brought in 7 Christian ministers to sanctify the process. Prior to etching, the wafer (pun intended) is doped with a mixture of holy water & oil. As the etching process takes place, the ministers intone the "Reverent Petition for Holy Quantumness" in q
Terrible news for cooks (Score:3, Funny)
how can I now be a cook at the same time as programming?
Before my Pentium 4 generated heat enough for frying eggs and I'm sure in a few years I would be looking for recipes suitable for heat generated by nuclear reactor( charcoal egg comes to mind) but now me dream is gone. Damn you University of Kentucky researchers. I hope we never meet
Kentucky University - more famous than Britain (Score:1)
Still, great tagline for the UoK though.