Slashdot Mirror
Memristor — 4th Basic Element of Circuits
esocid writes "Researchers at HP Labs have solved a decades-old mystery by proving the existence of a fourth basic element in integrated circuits that could make it possible to develop computers that turn on and off like an electric light. The memristor — short for memory resistor — could make it possible to develop far more energy-efficient computing systems with memories that retain information even after the power is off, so there's no wait for the system to boot up after turning the computer on. It may even be possible to create systems with some of the pattern-matching abilities of the human brain. Leon Chua, a distinguished faculty member at the University of California at Berkeley, initially theorized about and named the element in an academic paper published 37 years ago. Chua argued that the memristor was the fourth fundamental circuit element, along with the resistor, capacitor and inductor, and that it had properties that could not be duplicated by any combination of the other three elements."
http://technology.newscientist.com/article/dn13812-engineers-find-missing-link-of-electronics.html
This is very interesting stuff. I wonder if these will ever be produced for amateur use, or if they'll only ever find their way into DRAM and such..
- doctea
What are you talking about? V does not equate to capacitors any more then it equates to electric generators or batteries. And where on earth did you get inductance as i? In many cases capacitors and inductors behave fairly similarly (baring the fact that inductors have a charge time). If anything inductors relate to a delta i and not i directly.
Ohms law does not describe the basic componets of a circuit, it only provides a simply way to determine simple information about a simple circuit (Mainly a energy source, and a resistor). It has no room for capacitors or inductors. You need much higher math for that.
http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=207403521
- doctea
As for the others, they are components. For instance, a resistor R fits in dv = Rdi. A capacitor C fits in as dq = Cdv. An inductor as dphi = Ldi, and a memristor fills in the missing dphi = Mdq.
The only thing covered by Ohm's Law is the resistor, that being the "R" in V = iR.
For capacitors the equivalent law is i = C (dV/dt), and for inductors it's V = L (di/dt).
You can combine them all for an RLC circuit, but the result isn't Ohm's law.
The enemies of Democracy are
This one took quite a bit of thinking, although this wikipedia article summarizes it best.
A transistor may be approximated as a variable current source. Similarly, many applications of transistors are as "active" devices, which supply external power to the circuit being considered.
A diode is effectively nothing more than a voltage-controlled switch. In a DC circuit, it simply passes current through (with a small voltage drop that can be approximated by an inline negative voltage source).
Likewise, all transistors can be abstractly considered as networks of diodes. This is why they are inherently binary devices, and why computers "think" in binary.
The classical circuit elements (Resistor, Capacitor, Inductor) each fundamentally affect the electromagnetic properties of the electrons flowing through said circuit.
Resistors impede the flow of current; a capacitor is a current "bucket" that also blocks DC signals in AC circuits; and an inductor builds up a sort of inertia for the flow of current, through the creation of a magnetic field.
The distinction is hazy, but I think I can see it where it comes from.... when a diode/transistor does something, it affects of the "layout" of the circuit, rather than directly affecting the electrons flowing through it.
The memristor is extremely interesting, as it blurs the line between analogue components and solid-state devices, and provides exciting possibilities for the development of analogue computing and data storage.
Even more exciting is that they can already be made smaller than transistors, and two can be combined to create a device that functions analogous to a transistor.
Considering that we're quickly approaching the limits of Silicon-based technology, this invention may very well offer the key to the true "next generation" of electronic devices, and may very well be as significant to our generation as the transistor was to the previous. This is Nobel Prize-worthy stuff we're talking about.
Kudos to HP for supporting "true" R&D. They most definitely will be reaping the benefits of this one for years to come.
-- If you try to fail and succeed, which have you done? - Uli's moose
I don't get what they mean by "fourth fundamental circuit element"
There are four fundamental circuit variables; current, voltage, charge, and flux.
We can define the relationships between charge and current and between flux and voltage. (charge as an integral of current, flux as an integral of voltage over time)
A resistor provides a function to relate voltage and current.
A capacitor provides a function to relate charge and voltage.
An inductor provides a function to relate flux and current.
Until now we did not know how to construct a passive device which would provide a function relating charge and flux. The only remaining combination of these fundamental variables.
The difference between a memristor and FeRAM is that because the memristor is constructed without using any transistors, it can be used as a kind of analog memory. Instead of just storing 1's and 0's, it's resistance is an analog value anywhere in the range of on and off. Of course you can still use it to store digital data, but the real fun will come when you interconnect these things to emulate the analog behavior of the brain. This is where the claim of pattern recognition and facial recognition come in. They're not actually talking about software there but the actual analog capabilities of circuitry built with memristors.
The other amazing thing about memristors is how small they are. The articles state that you can emulate a transistor by connecting a few memristors, and that transistor is smaller than any we have today. Also it states that the memristor actually performs better at smaller sizes. This really is neat stuff.
The three elements we're used to (R, L and C) relate four things, potential, current, flux and charge. R relates current and potential, L current and flux and C potential and charge. The thing that relates flux to charge is this newfangled (compared to the other three) thing called a memristor. The other two relations (potential/flux and current/charge) are fundamental conservation laws.
At least that's what my quick Googling on the subject turned up.
The real "Libtards" are the Libertarians!
So what you're saying is that it's sorta like a capacitor, but instead of voltage, its function operates on flux.
How many gigawatts can it handle?
Why do you think it will be such a long time?
IBM discovered GMR and that was nearly universally used in hard drives within ten years.
Closer to 200 atoms wide. Take a glance at http://hyperphysics.phy-astr.gsu.edu/hbase/solids/sili2.html and notice the arrangement of the crystal (face-centered cubic) and the cube size. Going along one face, we pass two atoms before reaching the other side (one corner and one face center), so we have two atoms per 0.5 nm. Now chips are being mass produced on a 45 nm scale. This is about 100 times the silicon crystal cube size, with two atoms linearly per cube.
SIGSEGV caught, terminating
wait... not that kind of sig.
And that six-transistor radio I listened to as a young boy must have been receiving digital signals in 1965.
Look what the computer age has done: analog has been forgotten, even by bright minds.
But luckily not by everyone. The brightest minds still are aware that even the fastest digital 'gates' are fundamentally analog. Actually, especially the fastest....
But repositories of common knowledge are being filled with well-intentioned, but less-than-half-baked treatises and misinformation.
Transistors are IN NO WAY networks of diodes. Yes, some (bipolars) have a p-n junction, but there is no way that diode theory explains amplification. And don't get me started in fets (junction or insulated-gate). No diodes in those (except the packaged-in protection diodes in some). The jfets can be used to rectify, but that's not their nature.
I'm assuming some CS major wrote that wiki about something they didn't understand. Please don't be offended - that's not a stab at CS majors, but it was obviously someone "web-active" and had some (but inadequate) exposure to electronics.
(Disclaimer - I didn't read this wiki, so I'm taking for granted that moosesocks has lifted it from a wiki verbatim)
Ugh.
And to the GP - there is a fundamental difference between passive and active components.
To extend what you said, there are two problems we're seeing with current transistor technology.
Most inexpensive chip processes involve using blue and UV light to effectively (with chemical baths and deposition treatments) etch the surface of the chip into the correct shape and size. The biggest limitation here is that the light is around 300nm. When you're working significantly smaller than that, etching with this light is not as effective. Using higher frequency light can break down the materials (bathing things in xrays is generally a bad idea). One solution is to use refraction, which brings the wavelength of light of a given frequency to a smaller scale without increasing the energy of the light. This helps when etching smaller features (45nm is close to the limit of this hack).
To make smaller structures, they either need to grow them up, which takes time, or they need to build them individually using finer systems like electron guns. This can allow for tests on impossibly small transistors to see their behavior but are inefficient to produce for mass marketing.
The other concern is that with transistors, since you have charge being separated across a barrier (in a FET at least), the smaller the barrier is, the more likely you're going to breach it. If I remember correctly, and I may be wrong here, this should be related to leakage current.
I don't see us being able to make components smaller than the minimum etching size of 45nm. Since a transistor is usually larger than the minimum size (allowing for room for a gate and terminals on both sides, plus the width to allow for contacts to the silicon), this might still be an improvement.
What I'm wondering about is when people are going to realize that static memory prevents the benefits of a reboot. If a system is shutdown and its memory is still flooded by a program with a memory leak, it may not be recoverable. Better operating systems are handling this nicer, but I still need to reboot my machines from time to time to free up a few hundred megs of ram. I can imagine this might completely foobar a few machines without adequate memory cleanup.
Any thoughts?
I wouldn't consider the mad hatter mad. Just reality impaired. He sure can make a mean cup of tea.
Well, for starters, a transistor has a base, an emitter and a collector. A current flows from the base to the emitter which also lets another current flow from the collector to the emitter.
You have described a bipolar transistor. However, with field effect transistors, there is no current between the gate (base) and the source/drain (collector/emitter). In the case of a bipolar transistor, the emitter/collector current is controlled by the base/emitter current, whereas the source/drain current of a FET is controlled by the gate *voltage*.
The transistors used in CPUs are generally FETs.
http://blog.nexusuk.org
Unfortunately, everything about this device seems like higher math. If you bring in the Laplace representation, then Ohm's law becomes:
V = (R) i + (1/(s C)) i + (s L) i
This "memristor" is actually a function of the history of the electric flux going through the circuit:
V = M(q(t)) i, where M is the memristance
M(q(t)) = d Phi(t) / d q, where q is the electric charge particle
Phi = electric flux = integral of electric field E over an area A
E = electric force F / q
In physical terms, the resistance in the device changes over time with respect to the strength of the electric field and amount of charge that was flowing through it. I would think that you wire this up like a transistor, put a charge across it until the steady state resistance acts like an open circuit (infinite resistance) or short (zero resistance). Since the memristance is a also function of Area, the device can be minimized like any other electric component, which is why they say it could eventually replace memory storage devices.
That's why they say it's a new "fourth term" to Ohm's law,
V = (R) i + (1/(s C)) i + (s L) i + (M(q(t))) i
-- Scott