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To: Bilow who wrote (35789)	4/15/2001 3:45:06 AM
From: Bilow	Respond to of 275872

Hi all; Finally I find a (believable by all) reference showing why it is that CMOS runs faster at lower temperatures: Shorter Circuits Eric J. Lerner, IBM Research Magazine, 1998 ... While none of the new structures overcome the limits related to field strength and operating voltage, there is one way to cut voltages without compromising performance: lowering the operating temperature. Cooling the circuits reduces the thermal energy of electrons, allowing the transistors to function at lower voltages. There is also less scattering of electrons, resulting in higher currents and faster switching speeds. Cooling to 50 degrees C could improve performance by at least 50 percent, while cooling to liquid-nitrogen temperature would roughly double the speed. ... research.ibm.com The overall effect, from the point of view of the working engineer, is that CMOS transistors have a lower "ON" resistance at lower temperatures. This means that they drive the circuitry harder, and therefore faster. The equation for power consumption in a CMOS circuit doesn't have (much of) a temperature coefficient, as far as I remember, assuming that you don't have self timed free running circuitry. Consequently, running faster at lower temperatures raises power consumption. -- Carl

To: Bilow who wrote (35789)	4/15/2001 9:52:47 AM
From: fyodor_	Respond to of 275872

deleted

To: Bilow who wrote (35789)	4/15/2001 5:14:09 PM
From: Mani1	Respond to of 275872

Bilow Re <<I guess there's a bunch of guys out on the internet that have it all wrong:>> Not exactly, it is just that some guys do a internet search on a topic, then cut and paste stuff without a slight understanding of what any of it is all about. Thermisters are very unique in their temp vs conductivity and that is the reason they are used the way they are. Materials do not all have the same conductivity vs temp curve, but as a rule of thumb, In Cryo temps, material have less of electrical resistance than they do in room temperatures. In semiconductors, this is clearly the case which is what we were talking about. Now if you have nothing better to do than search for instances when "the sky is 'not' blue", be my guest. Mani