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IBM Creates Ring Oscillator on a Single Nanotube
deeptrace writes "IBM has combined CMOS circuitry and a single carbon nanotube to implement a 5 stage ring oscillator. Even though the oscillator runs at just 52 MHz, they expect that it could reach the GHz range with improvements. The frequency of the current oscillator was higher than previous circuits using multiple nanotubes. IBM describes the achievement in the paper "Integrated Logic Circuit Assembled on a Single Carbon Nanotube" to be published this week in the journal Science."
Religion for nerds. Stuff that really matters
Now let's talk about REAL innovation. Microsoft just announced a new facial feature pack for Office's "Clippy." Now you can customize Clippy according to your facial preferences. Options include complexion, hair style, nose shape and size, and ear/nose jewelry.
Microsoft announced today that they have achieved a full annoyance oscillator and generator on a single virtual piece of bent metal.
The findings titled "How to make Clippy more annoying" will be published next week in the Mr. Ballmer's Journal of IBM Bashing
Most semiconductors only turn on at a certain voltage level. For example, most silicon transistors turn on at about positive 0.7 volts. Any less than that and the trasistor won't conduct, even if you go below 0 volts to a negative voltage.
What the person was saying about nanotubes is they will "turn on" or begin to conduct again after the voltage drops below 0 to a certain negative level. Kind of like a device that takes the absolute value of the voltage, and if it's above a certain value it conducts or switches "on".
-- You are in a maze of little, twisty passages, all different... --
a ring Oscillator!
On a Single Nanotube!
crap all mighty!!!
They're just showing off.
It's nothing but a token ring.
=brian
Ring oscillators are simple circuits with which you can easily compare different circuit technolgoies. You simply scale the circuit to whatever your new design rules are, say 90 nm -> 65 nm, soi, etc. and measure the new frequency of the oscillator. This gives you a good base point for measuring and comparing the performance of the new technology.
...at the IBM labs Oh yeah! Nanotech really turns the hot chicks on
A carbon nanotube (CNT) is a rolled graphene plane (ie, carbon atoms in a hexagonal structure). So of course all current will be on the 'outside' of the tube, as the tube itself really only consists of the outside.
IBM was probaby comparing single-wall nanotubes to multi-wall nanotubes. Multiwall nanotubes are composites of a bunch of concentric single-wall nanotubes. Their better results in the single-wall variety are probably due to less scattering between the graphene planes. A single CNT has a well-defined crystal structure, and is actually quite interesting. The graphene plane itself is sometimes referred to as a 'zero-bandgap insulator', where the density of states linearly goes to zero at the fermi energy (unlike an insulator or semiconductor which has a energy gap at the fermi energy, and hence cannot conduct decently like a metal).
However through changes to the nanotube material, the performance of the nanotube may be impreved.
They probably can get to higher frequencies. I mean, even the vibrational phonon modes of a single nanotube can be in the GHz range or higher (ie, these are the various modes of vibration that the nanotube would exhibit if you struck it, kind of like a wind chime). I don't know specifics, but I don't see why the nanotube couldn't support electronic channels with bandwidths into the GHz or even higher as well.
Although nanotubes do have interesting characteristics different from typical metals and semiconductors. Ie, the electron-phonon interaction goes as 1/T, instead of 1/T^5 (where T is temperature). So at low temperatures there might be useful ways to couple electronic channels to vibrational modes not possible in conventional materials. Or vice versa, the phonon modes might more easily kill off electronic signals. There's alot of interesting work being done with nanotubes, and I'm sure some clever physicists and engineers will exploit these characteristics well in the near future.
That's the same circuit mentioned in the recent transparent IC story where TFA said
A 5-stage ring oscillator is the hardware equivalent of a program that displays 'Hello World!'
OK here's the explanation in 1337:
Carbon nanotubes = t3h w00t
CMOS = reality
Ring oscillator = first tests to integrate t3h w00t into reality
It means that before this, nanotubes and nanotube transistors were only tested in the lab, using microscopic clamps, cables, probes, etc. But this is the first time that a carbon nanotube can be integrated into a working CMOS chip (a small step for chips, a giant leap for mankind). Once CMOS manufacturing can be adjusted for carbon nanotubes, we'll be able to manufacture nanotube memory, nanotube chipsets, and finally, nanotube CPU's!
This is what i've been waiting for since i ever heard about nanotube transistors (however, i think that using graphene sheets instead of nanotubes will be much more effective).
Lets see if this helps. Some people were confused...
A ring oscillator is a device for making square waves. It uses a common component, a NOT gate. In digital logic, there are two levels, high and low (or 1 and 0, respectivly). High is usually, as far as I have seen, +5 volts, while low is 0 volts (ground).
A NOT gate simply inverts the input. If the value is 1, it outputs 0. If the value is 0, it outputs 1. If the value is somewhere between the two, it will choose one state or the other based on some threshold voltage.
Changing output is not instantaneous. How much time it takes, I don't know. However, it is very fast.
I was going to draw a schematic, but I gave up on appeasing the lameness filter. So, we will use the power of imagination! Imagine one of these NOT gates hooked up to itself. It will switch on and off at a terrific rate. Put a wire on the output, and you have a square wave! Want it slower? Take another two NOT gates, and put them in the loop, so that the first one goes to the second goes to the third. Slower? Another two. If the number of NOT gates was even, the inverted signal would be uninverted by the next NOT gate, which is not what we want.
For more control, one can use a capacitor in a certain arrangment (I'm not looking through my notes). It will take a while to charge and discharge, acting as a delay. Just don't read its voltage as the signal, or you will get a dropping bit, then a rising bit, rather than a nice clean square wave.
Quite useful devices. I hope this clarifies things.
I have freaks! I did something right...
Some people seem to be wondering if this is just showing off, or are there short to medium term applications for this? I think that one of the first, fairly simple applications for this is in the field of gate arrays. FPGA's, or field-programmable gate arrays, are cool devices that emulate strings of logic gates. They can be used in circuit design tasks, emulating loads on networks, and any number of geeky things. FPGA's are often considered the ugly step sister to application-specific integrated circuits, or ASIC's. Why? Because they suck more power and they're slower. People still use FPGA's a lot of the time because they're more flexible, you can change them on the fly. Now imagine an FPGA that's ultra-miniaturized, drawing almost no power, producing very little heat, and operating at amazing speeds. They need to perfect NAND or NOR gates, but once they have one of those, they can replicate them a billion times, and either of those gate types will be able to emulate every other logic gate, when placed in the right order. That's one interesting application, on the pure logic level. So it might be an exciting time, depending on how quickly they can move this out of the lab. I love this stuff.
Bill Ricardi - Jigsale LLP
against ring osculation. It's disgusting and vulgar. What's wrong with just holding hands, or kissing on the lips? Miss O'Tube should be ashamed of herself. With a reputation like that, she's going to stay single. Back to you, Cheddar.