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UIUC Creates World's Fastest Transistor Again
An anonymous reader writes "The University of Illinois has developed (again) the world's fastest transistor operating at over 500 GHz. They used an indium phosphide based wafer, and super-scaled dimensions. The device kind of looks like a spaceship." Milton Feng, the professor in charge of the team behind the transistor, admits that their ultimate goal is a terahertz transistor, which given their previous achievements, doesn't sound too lofty.
True -- but you can't use these on a normal chip. The potential pitfalls are huge... you need to be able to get enough of them into a small space, you need to be able to dissipate the power, the manufacturing process needs to be cheap enough to be economically viable... and so on.
A single transistor isn't all that impressive by itself :-)
(Actually, does anyone know how fast the transistors on desktop processor are? Each clock cycle has to wait several transistor delays, after all.)
This isn't a FET like the transistors found in computers (and just about everything else). This is bi-polar technology that uses much more power than FET. They're looking for speed only to make possible very demanding applications like direct microwave processing.
It seems like every time an article like this is on slash dot a million people say "wow I can't wait for a computer using that technology".
What people _don't_ understand is this is not the same technology as is used in a microprocessor. CPUs used Field Effect Transistors. The advantage of FETs is that there is no gate-drain current when the transistor isn't switching so they take very little power. With a bi-polar transistor, you are using a current switch, which would take massive amounts of current if you put many of these into an IC.
A more realistic application would be in communications systems where your carrier frequency is at 500Ghz.
Sorry to burst your bubble but you won't see 500Ghz computers next year. Maybe not ever using CMOS.
How does a faster transistor have anything to do with Moore's law. Moore's Law is all about doubling the number of transistors every 18 months. It has nothing to do with how fast those transistors are.
Sorry, teleporters just kill you and then make a copy. A perfect, soul-less copy.
The speed they're talking about is typically GBP (gain bandwidth product), or the frequency at which the gain of the transistor is 1. It's not typically useful at a gain of 1 (for instance, if you want to fan it out to like transistors, it'll need to be at least n for n fanouts).
The clock speed on a chip is significantly slower than the speeds they're talking about because in order to achieve that external clock speed, the individual components must be faster. Say you had a P4, with its 20 stage pipeline. Each pipeline stage must complete in a clock cycle. However, say there's a propagation of say, 10 transistors for the output at the end of that pipeline stage to be valid. Each individual transistor would have to be 10 times as fast as the clock speed in order for the processor to work.
There will not be 500GHz or 1THz computers any time soon, at least not without extremely long pipelines and even faster transistors than this (to accomodate a useful fanout value).
Every time an article quoting a GBP-derived transistor speed comes out, everyone misunderstands this issue, so, here it is.
You use the transistor to build a ring oscillator and measure the resulting frequency, then divide by the number of stages.
Disclaimer: I am not professor of EE (just undergrad)
Quote:"The steady rise in the speed of bipolar transistors has relied largely on the vertical scaling of the epitaxial layer structure to reduce the carrier transit time,"
Translation: bipolar transistors (BJTs) have gotten faster because they made them thinner (less distance for electrons to travel)
Quote: "However, this comes at the cost of increasing the base-collector capacitance. To compensate for this unwanted effect, we have employed lateral scaling of both the emitter and the collector."
Translation: Speed gained by making the transistor thinner was offset by the effects of increased capacitance (capacitance is proportional to area/separation, and they decreased the separation), so they made it skinnier as well (lowering the area) to lower the capacitance.
Summary: They made the transistor smaller, so it goes faster.
Anyway, based on the parent's comments, these are just BJT's (Bipolar Junction Transistors), which are fine for high speed stuff, but aren't used in computer processors or any of the stuff you would commonly think of using transistors in. BJT's have horrendous power consumption because they always use power constantly, while CMOS (which has replaced it) only uses power when it changes state.
This means that these advances will be great for communications and signal processing, but won't affect most of the electronic devices we know and love.
This is bipolar transistor, odd are it'll never make it into your computer cpu where CMOS is king. This transistor is for high frequency RF analog circuitry.