http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/ Engadget Comments for Transistors nearing the one terahertz barrier http://www.engadget.com/media/feedlogo.gif http://www.engadget.com en-us Copyright 2009 Weblogs, Inc. The contents of this feed are available for non-commercial use only. Blogsmith http://www.blogsmith.com/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 12th 2006 11:23AMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/
dude 1: Hehe remember when someone said that we would end up needing more than 1Thz, I've still got my Ahtlon 128, how about you?

dude 2: Core Octo]]>Dec 12th 2006 11:49AMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/
Why does my computer still have a 2.4Ghz processor?
Something is wrong here.]]>Dec 12th 2006 11:57AMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 12th 2006 12:29PMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/
Figure out what you're talking about before trying to correct others.]]>Dec 12th 2006 6:37PMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 12th 2006 12:49PMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 12th 2006 2:31PMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 12th 2006 2:35PMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 12th 2006 5:26PMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/
Bill Gates said that.

]]>Dec 13th 2006 6:33AMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 13th 2006 10:52AMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/
The number of 845GHz being quoted here is one of two figures of merit known as cutoff frequencies. Whether it's f-sub-T or f-sub-max (I'll use fT and fmax for short), I don't know until I read the paper. Due to budget cuts at my company, I didn't get to attend IEDM this year (although I'm a co-author on a paper being presented there).

Most likely, they are quoting fT. Imagine a transistor set up like an amplifier and applying a continuous signal at the input at one frequency. As you turn up the frequency, the current gain of the device drops. At some point, this gain drops to 1 and the device can no longer be said to have any useful gain. The frequency at which this occurs is fT. A similar figure of merit, fmax, can be defined based on power rather than on current gain.

These figures of merit do not represent the clock speed of a processor made with such a device. In fact, bipolar transistors aren't very useful for implementing digital logic in the first place because logic gates based on these devices draw current at all times and thus dissipate too much power. This fact plus the larger size of these devices compared with FETs means low density and not enough transistors on a chip to create a modern processor.

Instead, expect devices like this to appear in RF or mixed-signal applications. In such applications, you want fT and fmax to be much higher than the carrier frequency at which your system will work ... a factor of 3 or more is typical. Right now, you can buy HBTs made from silicon-germanium with fT values of 200GHz and fmax values of 275GHz being used to build 60 and 77GHz radio systems. This gives you an idea of the margin. SiGe HBTs have achieved fmax values of over 500GHz when chilled, by the way.]]>Dec 13th 2006 5:12PMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/I'd like to learn more about this, would you mind contacting me offline please?
+447966347407 or edward.french (at) enterprise-ventures.co.uk
Cheers,
Edward French ]]>Dec 15th 2006 6:58AMhttp://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/http://www.engadget.com/2006/12/12/transistors-nearing-the-one-terahertz-barrier/Dec 16th 2006 12:19AM