I have measured data using the pulsed modeling system, some DC-IVs. Since there is no pulsed FET model, I tried to import the data into the CGaashf.mdl/dc/idvd_vg setup but when I click extract it tells me 'lnarg not positive in find_gamma'. It imports correctly because I can see it on the plot, but the extract transform doesn't recognize it. What did I do wrong?
It is not possible to give an exact diagnosis of the cause of the problem from this description. The concept, to import some measured data into an IC-CAP model and do extraction is reasonable, as long as the type of model chosen is appropriate and the data maps into existing setups and is well-behaved per the requirements of the extraction functions.
It sounds like this basic criteria is met for your case, i.e. I will assume you are trying to run the extract transform under the dc/idvd_vg Setup in CGaashf.mdl, which calls the GAASDC_cur2 function.
What I would consider first, is how well-behaved your data is... Are there any values which are negative, or any data discontinuities etc. Definitely suggest reviewing the data, both in terms of discontinuities, or changes in slope or unexpected negative values.
I did a small experiment, with the data in the default CGaashf.mdl dc/idvd_vg setup, Extract(GAASDC_cur2)function, which has vd, vg and id.m as inputs, and I noted that if I put a - (minus) sign in front of id.m, that if you then execute the xfm, the error you mention is reported:
Error: Inarg not positive in find_gamma
To summarize: the first suggestion is to examine the id.m data you have for any irregularity, non-linearity etc.
If this does not enable you to identify the cause of the problem, please contact Agilent EEsof Technical Support.