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#analog-design
Title
# analog-design
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Eslam Morsie

07/26/2021, 11:37 AM
Is there anyone here tried to make corners simulation using the command 'altermod' in ngspice?
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Tim Edwards

07/26/2021, 12:49 PM
That would be a really roundabout way of doing a corner simulation. Why do that instead of using the corner simulation models directly?
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Eslam Morsie

07/26/2021, 12:51 PM
I want to run more than one corner in the same run, I found in the manual that altermod command do that but I didn't figure out how to do that.
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Tim Edwards

07/26/2021, 12:51 PM
My advice is not to do multiple corners in one run.
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Amro Tork

07/26/2021, 1:25 PM
@Tim Edwards I wanted to ask you about this why not? Using such technique usually speeds up the simulation. Because it doesn't have to rebuild the circuit in memory only loading models.
@Eslam Morsie I think let's follow @Tim Edwards advise for now.
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Eslam Morsie

07/26/2021, 1:26 PM
ok
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Tim Edwards

07/26/2021, 1:27 PM
@Amro Tork: Ideally, yes, but in practice it's just a pain to work with ngspice's built-in command language, and it makes everything unportable (e.g., to xyce).
Once upon a time, the tclspice version of ngspice worked really well for those kind of things, but it has been broken for years.
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Amro Tork

07/26/2021, 1:29 PM
@Tim Edwards I used to do that with most of commercial tools: ELDO, Spectre, HSPICE, etc...
@Tim Edwards I understand that whatever @Eslam Morsie doing is not going to be portable to other tool like Xyce. But is there any limitations in the model cards files that I should look out for?
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Tim Edwards

07/26/2021, 2:56 PM
@Amro Tork: As far as I'm aware, there are no particular issues currently for running with ngspice other than the fact that a lot of the models are binned over narrow L and W ranges and are not at all well characterized outside of those ranges.
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Amro Tork

07/26/2021, 6:20 PM
@Tim Edwards Thanks for all the help.
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