Magnetic Transistor Could Cut Power Consumption and Make Chips Reprogrammable 126
ananyo writes "Transistors, the simple switches at the heart of all modern electronics, generally use a tiny voltage to toggle between 'on' and 'off.' The voltage approach is highly reliable and easy to miniaturize, but has its disadvantages. First, keeping the voltage on requires power, which drives up the energy consumption of the microchip. Second, transistors must be hard-wired into the chips and can't be reconfigured, which means computers need dedicated circuitry for all their functions. Now, researchers have made a type of transistor that can be switched with magnetism. The device could cut the power consumption of computers, cell phones and other electronics — and allow chips themselves to be 'reprogrammed' (abstract)."
Re:Chips are "reprogrammable" (Score:5, Informative)
To keep a magnetic field going (small as it might be) you need to have a current flowing...
And that's why I have wires and batteries connected to all my fridge magnets...
Re:Chips are "reprogrammable" (Score:4, Informative)
If you can change the chip logic, you can get custom behaviours at top speed.
That's what we thought about FPGAs, but it didn't quite work out that way. Using this technology won't change that, it will just allow us to make better FPGAs.
Reprogramming an FPGA is slow (many switches to reconfigure, usually serially), which means it would only increase overal performance if you can use the custom function long enough, and it only works if you don't have to switch functions too often.
Writing software for an FPGA is difficult (it's more logic design than software) and requires specialized software. Reconfiguring it in a wrong way could damage the silicon (though modern devices and software have some protections and checks). So any custom functionality would come in the form of libraries, written by specialists.
The amount of extra interconnect and transistors needed to make a CPU reprogrammable are also significant, resulting in higher die area (and thus cost), lesser transistor density (=slower speed), and overall higher energy consumption.
The result of all this is that FPGAs are only used in very custom hardware (usually low volume), with the programming remaining largely static, only to be altered when there are bugs found or improvements needed (once a month or less).
Re:Chips are "reprogrammable" (Score:4, Informative)
However, it could be possible to use magnetic nanoparticles to provide that magnetic field, which is the solution proposed in the second half of the article. A stronger-than-normal electric field could be used to rotate those magnets. The problem is that building such a structure is very difficult. A bottom-up nanotech approach combined with our current top-down lithography would introduce far too many contaminants. Trying to get a nanoparticle solution to go exactly where you want it is extremely difficult, especially due to the high surface forces that make nanoparticles like to stick to things. The difficulty of using a traditional top-down approach is making the nanoparticles able to rotate. There would need to be multiple types of resist used, likely, one to define the shape, and the other to be removed at the end to provide spacing during fabrication. The high surface forces as mentioned previously would also pose a big problem. Nanocrystals lack the stability given by long-range order and, especially with sub-10nm crystals, can have unique crystal structures due to this large stress. In order to mainain stability and not try to merge with neighboring crystals, there either needs to be an electrostatic barrier or physical barrier. Because it's impossible to keep something passively balanced with a electric or magnetic field, there would need to be the additional complexity of a pivot placed at the necessary angle. It's possible that something like graphene could be used to provide lubercatoin of the pivots, but this means that both the graphene and magnet would have to have compatible crystal structures so that the depostion growth grows with a known crystal orrientation (for knowing where to place the pivot).
On the other hand, this technology could be very useful with current technology in MEMS (microelectromechanical systems). A field of these transistors could be used to very accurately know the position of a magnet, in, say, an actuator, or on a spring for an accellerometer.