temperature dependent Un and Vth

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tepmerature depedent Un and Vth

As temperature increases, the mobility Un and the threshold voltage Vth both decreases. For the current I=0.5*Un*Cox*(W/L)*(Vgs-Vth)^2, the Un decreases, and (Vgs-Vth)^2 increases, so whether the the transistor becomes fast(current increases) or slow (current decreases? Thanks.
 

Re: tepmerature depedent Un and Vth

In pre-FinFET technologies (i.e. ~20nm node and older), Vth temperature dependepnce dominates at low Vgs, while mobility temperature dependence dominates at high Vgs.
There is one point on Ids(Vgs) curves (slightly above Vth, as far as I remember), where current is approximately constant vs temperature - it's called temperature compensated point.
Above that (higher Vgs), current decreases with temperature, and below that point, current increases with temperature.

In FinFETs, many aspects the old knowledge (including Ids(T) dependence) is no longer valid.
 
Re: tepmerature depedent Un and Vth

The paper below explains the phenom of threshold voltage and mobility temperature compensation.

I. M. Filanovsky and A. Allam, “Mutual compensation of mobility and threshold voltage temperature effects with application in CMOS Circuits”. IEEE Transactions
on Circuits and Systems, July, 2001. vol. 48, pp. 876-884.
 
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