Effect of temperature on ICs

[Quad]

In general, what major effects do increasing/decreasing temperatures have on integrated circuits?

Since the conductivity of semiconductors increases with temperature...does this allow circuits to operate faster at higher temperatures?

What other effects are there?

Thanks

 

[The Boston Dangler]

On your CPU, do you have a heatsink, or a small blow torch?

Conductivity decreases with an increase in temperature.
Thermal noise, RFI, increases with temperature.
Signal attenuation increases as frequency increases.

 

[coomar]

i could test it out a little, we just got our 25 degree drop (canada doesn't really have fall, it has summer and pre-winter)

 

[smack Down]

For digital circuits temparture doesn't have much effect but analog circuits are effected alot more. Most data sheets will tell you what effect temparture has. One very basic temperature sensor is to use a dioded and measure the voltage to get temparture changes.

 

[Navid]

Originally posted by: Quad
Since the conductivity of semiconductors increases with temperature...does this allow circuits to operate faster at higher temperatures?

The conductivity of a pure semiconductor does increase as temperature goes up (you are absolutely right about that). But, that does not mean that circuits operate faster at higher temperatures!

Circuits (and their elements, transistors) are not made with pure semiconductors. They are made with doping and adding (diffusing) impurities to the semiconductor to create p-type and n-type materials (p-type and n-type Silicon for example).

The maximum operating frequency of an integrated circuit decreases as temperature goes up.

 

[The Boston Dangler]

Conductivity decreases with temperature. The FCC requires I measure this drop and rise every winter and summer. As temp goes up, the conductor expands, the molecules expand, and lose some ability to cunduct electricity.

 

[Navid]

Originally posted by: The Boston Dangler
Conductivity decreases with temperature. The FCC requires I measure this drop and rise every winter and summer. As temp goes up, the conductor expands, the molecules expand, and lose some ability to cunduct electricity.

That is true for a conductor (metal).
But, for a pure semiconductor, that is not!

http://www.newton.dep.anl.gov/askasci/phy00/phy00527.htm

http://encarta.msn.com/encyclopedia_761578100/Semiconductor.html
From this one:
At low temperatures, pure semiconductors behave like insulators. Under higher temperatures or light or with the addition of impurities, however, the conductivity of semiconductors can be increased dramatically, reaching levels that may approach those of metals.


But, as I said, a transistor is not made from a pure semiconductor. Rather from doped semiconductors.

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/intrin.html

 

[SixEyedSmily]

pffft cant delete