-
Notifications
You must be signed in to change notification settings - Fork 56
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
VTH vs. W #46
Comments
Below is a plot from the measured data: It is expected that Vt is a strong function of W near the minimum allowed value (due to narrow width effects). The above data also shows this. But I would not expect is that Vt changes dramatically as the width changes from ~1-10um. The Vt value usually stabilizes for large W as shown here: https://www.semanticscholar.org/paper/Implications-of-Small-Geometry-Effects-on-%24g_m-I_D%24-Ou-Ferreira/7982fbeb3a43c594a244923438360aa5ebd1b478/figure/4 Looking at the measured data, I see identical Vt for W=0.6 and W=2um, which makes sense to me (but the current models do not reflect this). Perhaps the measured data (with potential outliers) was overfitted to generate a non-physical trend in the spice models? |
@dwarning could you please share your testcase? I would like to get the exact difference between model and the measurements. |
@claudiotalarico first of all we are sorry to let you wait such a long time for response. Reviewing your simulation you use W in a range up to 50u. Our models are valid up to 10u and to obtain W=50u one should use multi-finger approach. Could you please regenerate the graphics to be aligned with the one we have shared in this thread ? I mean semilogx axis for width and vertical grid of 50 mV. |
Maybe this issue is related to #164? Could be if the number of fingers is also changed in the investigations above. |
The change in VTH when sweeping W seems to be excessive (especially going from 5um to 10um).
Please see the attached plots (the device used for this analysis is the SG13 LV nmos)
The xschem's file and the matlab's file I used to generate the analysis are provided at this link
The text was updated successfully, but these errors were encountered: