Per Horowitz&Hill book, the Ebers-Moll equation for the collector current in a BJT is:
Ic = Is (e ^ (Vbe/Vt) - 1) where Ic is the collector current and Is is the saturation current.
Now, I am sure different BJTs (say, 2N2222, 2N3904, BC548,...) produce different amounts of collector current for the same value of base-emitter voltage Vbe.
(Q1) Would it be fairly correct to model those differences just by taking different values for Is?
In some books, the equation includes an ideality factor in the exponent. So, the equation gets written as Ic = Is (e ^ (Vbe/(n*Vt)) - 1) where n is the ideality factor. With that, the differences in collector current values for different BJTs can be accounted for by selecting different ideality factors while taking Is to be the same. That leads to my second question: (Q2) Is it more accurate to model the differences in collector currents by taking different values for Is or by taking different values for the ideality factor?
Thanks! P.S. My context: I am writing a simple simulator for BJTs.
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