Memristor — 4th Basic Element of Circuits
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[edit] Summary
"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."
[edit] Interesting comments
This one took quite a bit of thinking, although this wikipedia article [wikipedia.org] 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.
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.
- Exactly! After reading the few articles, wikipedia and the available information from HP, it looks more like a generational change in technology rather than just a new kind of memory. I think the Nature article's wording of discovery is correct here, this looks like an interesting piece of base research with large real world applications, instead of a specific invention to store things.
- Given that this memristor looks like to be using very little power, can be scaled down very well and can be used both as storage and to build transistors - I'm pretty excited about this. Yeah, there are other attempts at non-volatile ram, but they are either slow (flash), cannot be written to many times (flash), expensive (a lot of flash alternatives) or just simply too energy consuming, the memristors should bring in some nice competition into the field, since the articles specifically state that it doesn't generate much heat at all, compared to currently existing other technologies, it can be made to change state faster than they could measure(!) in the lab and it can be repeated many times. So, the only part that is left is whether it is economically feasible to mass-produce these. I'm guessing it shouldn't be a very large problem either given the relative simplicity of this discovery.
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