Slashdot Mirror
Super-fast Transistors On the Way
nbannerman writes "The BBC is reporting about a new kind of transistor, that recently set a world record of 110Ghz. From the article: 'To achieve the speed gain, researchers at the University of Southampton added fluorine to the silicon devices. The technique uses existing silicon manufacturing technology meaning it should be quick and easy to deploy.' The apparent applications for this process include mobile phones and digital cameras."
They're talking about transistors, not entire processors. High speed transistors are needed for the RF front-end, where analog signals up to 1 GHz or so are encountered. These signals require devices that can switch at speeds significantly faster than the signal frequency. Formica
The faster the chip cycles, the higher the communication frequency can be. It is difficult to do noise-reduction calculations on ultra-high frequency communications without chips that cycle at the rate of data transmission.
No, because whenever Slashdot covers these ultra-high-frequency transistors, they never bother mentioning that there's a huge difference between transistors optimized for logic (always on/off, usually very high drive levels and low gain, fast switching of square waves) and transistors designed for RF signal amplification (Usually designed for linear amplification of sinusoidal or modulated sinusoidal signals, lower drive levels with higher gain, and no one cares about the switching time, just the highest frequency sinusoid at which the device exhibits gain.) In essentially every case, the article is covering amplification of a signal at the record-setting frequency, not operation of a logic gate at that frequency.
There is also a very good chance that while the manufacturing process may be suitable for single (relatively) large tranistors (perfectly suitable, and often desireable for RF), it is not suitable for integrated circuits with multiple tranistors and other components on a die. Gallium Arsenide is a perfect example of this - The IC industry gave up on it pretty quickly because it was simply too difficult to make integrated circuits with it and the performance benefits for logic circuits weren't worth the costs, but manufacturers of RF transistors are still putting large amounts of effort into GaAs and plenty of commercial products exist. (Yes, there are still issues with GaAs technology and a lot of companies still don't trust GaAs in their products except in low-volume high-performance applications, but it's not like logic circuits where nothing exists on the market.)
Same thing with IBM's big SiGe push - great for RF but doesn't seem to have made any inroads to logic, probably due to cost issues and technical problems that make SiGe potentially unsuitable for logic but don't really affect their RF performance.
retrorocket.o not found, launch anyway?
RTFA
This isn't about CMOS, for a change. This is about analog power amplification and the 100GHz figure quoted is either the maximum frequency of current or power amplification. Too bad the BBC doesn't say.
Most cell phones contain one Gallium Arsenide bipolar transistor to amplify the signal going to the antenna. This faster Silicon transistor would open up other transmission frequencies but it wouldn't make that game of Alchemy play any faster.
A sig! What kind of person do you think I am?
Actually, the article says that they created a BJT transistor
"The research was carried out using a simple type of transistor known as a silicon bipolar transistor."
Processors use FET transistors because BJT transistors need current to bias them all the time. These transistors would consume way too much power to make any sort of processor (especially for mobile devices). As others have commented, this would only be useful for the analog processing of the output transmitter.
Like pi? Try 10,000 digits.