How to set the model parameter STIMOD in simulation?

OK, I tried replying just now, but my connection timed out. I'll try again and combine everything into one post.

First of all, apologies for the missing file - I'd forgotten that the forum site only supports certain suffixes on files, and .scs is not one of them. However, the file is identical to the indented piece of text in this earlier post of mine in this thread. So cut and paste that text into a file called teststimod.scs and then run spectre on it. Run it first without the pipe and grep, and if it works by all means pipe the output into grep to spot the stimod output.

Secondly, your attempt to run it failed because you had library and section statements in the file, and as I'd said before you can't run that directly with spectre. They only work if you include the file, using something like include "thefile.scs" section=blah.

Thirdly, stimod=0 is using the Berkeley model, and stimod=1 or 2 means using the TSMC LOD model. So that's different from what your friend said. That said, 4.3 was so long ago, I think it's always worked this way (and stimod has only been supported in spectre since MMSIM61 (2005). Maybe it was an HSPICE-specific extension at some point and then they changed the behaviour to match the standard? That said, some of the changes in behaviour have been at the behest of certain foundries.

The way that you've modified your file in your final post append is fine, but it won't output anything about stimod on the output because presumably you didn't add:

  models info what=models where=screen

which is running an info analysis but directing the output to the screen, rather than to a rawfile (the binary database usually used in ADE). So it's not surprising it doesn't print anything.

And all that ".scs" indicates is that the file is in spectre syntax. The default is that any file that spectre reads is in SPICE syntax, unless the file ends with a .scs suffix - and avoids you having to use the "simulator lang=spectre" construct to switch to spectre's more regular syntax (SPICE is quite archaic and rather irregular).

Next, MMSIM72 is quite old - and the version you're using is almost 4 years old. I somehow doubt that's got anything to do with the issue - maybe you modified the models in the wrong section. TSMC models are quite complex as they have a complex nesting of includes. For example, you include in your netlist the section=tt, but within the definition of the file you're including, in the tt section, it will go on to include other sections (e.g. the mos section) from a named file. So did you update the includes in the tt section to include your modified teststimodModel.scs or is it including the original model file? If so, it will be completely missing your modifications because it goes on to include the original file. Be careful because there are lots of includes in TSMC models of various sections. This is the most likely explanation as to why you don't see the stimod parameter change having an effect, in my opinion.

Finally, why are you modifying a foundry's carefully characterized models anyway?

Regards,

Andrew.

OK, I tried replying just now, but my connection timed out. I'll try again and combine everything into one post.

First of all, apologies for the missing file - I'd forgotten that the forum site only supports certain suffixes on files, and .scs is not one of them. However, the file is identical to the indented piece of text in this earlier post of mine in this thread. So cut and paste that text into a file called teststimod.scs and then run spectre on it. Run it first without the pipe and grep, and if it works by all means pipe the output into grep to spot the stimod output.

Secondly, your attempt to run it failed because you had library and section statements in the file, and as I'd said before you can't run that directly with spectre. They only work if you include the file, using something like include "thefile.scs" section=blah.

Thirdly, stimod=0 is using the Berkeley model, and stimod=1 or 2 means using the TSMC LOD model. So that's different from what your friend said. That said, 4.3 was so long ago, I think it's always worked this way (and stimod has only been supported in spectre since MMSIM61 (2005). Maybe it was an HSPICE-specific extension at some point and then they changed the behaviour to match the standard? That said, some of the changes in behaviour have been at the behest of certain foundries.

The way that you've modified your file in your final post append is fine, but it won't output anything about stimod on the output because presumably you didn't add:

  models info what=models where=screen

which is running an info analysis but directing the output to the screen, rather than to a rawfile (the binary database usually used in ADE). So it's not surprising it doesn't print anything.

And all that ".scs" indicates is that the file is in spectre syntax. The default is that any file that spectre reads is in SPICE syntax, unless the file ends with a .scs suffix - and avoids you having to use the "simulator lang=spectre" construct to switch to spectre's more regular syntax (SPICE is quite archaic and rather irregular).

Next, MMSIM72 is quite old - and the version you're using is almost 4 years old. I somehow doubt that's got anything to do with the issue - maybe you modified the models in the wrong section. TSMC models are quite complex as they have a complex nesting of includes. For example, you include in your netlist the section=tt, but within the definition of the file you're including, in the tt section, it will go on to include other sections (e.g. the mos section) from a named file. So did you update the includes in the tt section to include your modified teststimodModel.scs or is it including the original model file? If so, it will be completely missing your modifications because it goes on to include the original file. Be careful because there are lots of includes in TSMC models of various sections. This is the most likely explanation as to why you don't see the stimod parameter change having an effect, in my opinion.

Finally, why are you modifying a foundry's carefully characterized models anyway?

Regards,

Andrew.