Geoffrey_Coram wrote on Jun 12th, 2007, 4:14am:kiran123 wrote on Jun 12th, 2007, 12:50am: what is this "pParam->" declaration ? where should i mention this to get "phi" value ?
i understood that the above equation is looks like
"phi" = 2 * kt/q * log( ni / NA)
can i take kT/q = 26mV at 300k
& ni = 1.45* 10^10 cm^-2 otherwise where from i should get ?
NA = nsub or nch ?
pParam is a data structure in the BSIM3 source code (having to do with sharing values for devices with the same L and W).
You inverted the division in the log, it's log(NCH/ni), and NCH is the parameter.
ni = 1.45e10 * (Tnom / 300.15) * sqrt(Tnom / 300.15) * exp(21.5565981 - Eg0 / (2.0 * Vtm0));
You should double-check that Tnom in the model card is 27.0 C (which would be 300.15 K), else you'll have to adjust ni and kT/q from what you are using; then again, you may not care to be all that exact.
Geoffrey,
Thanks a lot for sharing helpful information on this , if possible can you tell me why should NCH is to be consider instead of nsub, some text boox says it is nsub i.e equivalent SPICE parametr name is NSUB
from the model file information i found below definition for them
NCH: Peak Channel doping concentration
Nsub : substrate doping concentration
thanks
Kiran