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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.
Sweet, now the 250 Ghz's will be totally affordable.
The University of Illinois has developed again the world's fastest transistor operating at over 500 GHz
If only they had documented the damn thing, they wouldn't have to develop it twice!
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.
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.