McSim
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Posts: 8
Moscow, Russia
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Dear colleagues!
I deal with SPICE models for SOI MOSFETs. Self-heating effect is one of the most important problems for the designer because it's difficult to obtain the values of cth0 and rth0 parameters.
My objective is to study or develop the methodology for the extraction procedure for these parameters.
Unfortunately I actually don't know how this effect is modeled by simulator. BSIMSOI model has a separate pin "t" for the "intrinsic" temperature, but how is this information used by simulator?
I found the following formula: P=ΔT/rth + cth*δ(ΔT)/δt, where ΔT is the difference between "intrinsic" temperature and ambient, t is time, P is the power dissipation.
How this "P" is used for recalculation of Ids?
In another words, it's unclear for me how a simulator solve the equations for SHE. Let's consider the simple example: 1) Ids is calculated. 2) P=Ids*Vds. 3) A simulator "knows" rth and cth. 4) As far as I understand the simulation process, Ids is to be recalculated to obtain a negative output resistance (static IV). The first question is how to recalculate Ids? The second is the following: does "P" is also recalculated after the Ids changing? So, when will the recalculation process stop?
Thanks in advance.
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