#668 onoise_total is NaN

[Michael Köfinger]

Hello!

Sometimes, the integrated noise results are NaN in plot noise2, even though the plot noise1 gives a valid output noise spectrum. Unfortunately I could not find a test case to reproduce this issue.

I have attached two example netlists, in tb_filter_cl.spice, the integral is evaluated correctly, in tb_amp_ol.spice, the value is NaN.

It seems as this has already been reported a few years back

https://sourceforge.net/p/ngspice/bugs/92/

I'm using Ngspice 42

Best regards
Michael

[Dietmar Warning]

The problem still exists - I reopened bug #92 and will use the old test case.
Your testcase is to complex. Main problem is that your PDK installation differs from mine.
Which github you have cloned for the skywater PDK?

[Michael Köfinger]

I'm using the IIC-OSIC-TOOLS docker container
https://github.com/iic-jku/iic-osic-tools
According to the readme it should be this PDK
https://github.com/google/skywater-pdk

Thanks!

[Dietmar Warning]

Michael,
could you be so kind and checkout git pre-master-43 branch, build a 42+ version and check if the problem still exist.
Or wait until new release 43. A workaround could be to reduce the points per decade in your analysis command.

[Michael Köfinger]

Thanks for the quick workaround, fixed the problem in tb_amp_ol.spice
Unfortunately, I've not the time at the moment to get into building a new ngspice version. Will wait for the next release.

Thanks for the fast response!