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Other CAD Tools >> Entry Tools >> Parasitic extraction with Assura
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Message started by asdf on Oct 28^th, 2005, 3:53am

Title: Parasitic extraction with Assura
Post by asdf on Oct 28^th, 2005, 3:53am

I use Assura RCX and need to get extraction output in Spectre fornat but generated output file contains some statements that are not in Spectre syntax.
e.g.
1. it contains .SUBCKT and .ENDS statements
2. the unit prefixes (microns) are in higher case U but it need to be in lower case
3. when in resalt are included parasitic resistance models as a coment the comment begines with $ sign which is not in spectre sintax

I cannt find where must be made the changes to get correct resalts, please help!

Title: Re: Parasitic extraction with Assura
Post by Paul on Oct 28^th, 2005, 5:24am

I'm not sure you can do this inside Assura. Maybe you can request a SPICE netlist instead of Spectre format (see the user's guide on that), so you will at least get the .subckt and .ends statements. For the rest, I suggest you write a script (e.g. in Perl).

Paul

Title: Re: Parasitic extraction with Assura
Post by bernd on Oct 28^th, 2005, 6:30am

AssuraRCX can output various formats depending of the version
you are using.
?outputFormat { “spice” | { “dfII” | “dfii” } | “dspf” }
In general I use Assura out of DFII which then is the best bet to use
dfII as the output format and generate an so called extracted view which
easily can be plugged in to your simulation testbench with the hierarchy editor.

I assume you use Assura in batch mode?
If you select Spectre as an output format Assura first generates a Spice netlist
then it starts a postprocessing to generate the Spectrec netlist out of the Spice one.
Which I think is a bit poor implemented, so no direct Spectre netlister here.
I don't know, but might be that this could cause your problem.

See the Assura Command Reference & and User Guide
documentations and have a look for this tow commands
?outputFormat { “spice” | { “dfII” | “dfii” } | “dspf” }
Which defines the out put format.
?pipeAdvgen "spp -convert -log <cellName>.scs.log"
Which redirects the Spice netlist to a Spectre one, 'spp'
is the Cadence Spice reader which is also be used by Spectre
to convert real Spice models for simulation purpose.

Bernd

Title: Re: Parasitic extraction with Assura
Post by Paul on Oct 28^th, 2005, 2:40pm

After reading Bernd's answer, I noticed that I completely misunderstood your initial post... Thought you wanted to get the features you list, not the opposite. My apologies, fortunately week-end's close.

Paul

Title: Re: Parasitic extraction with Assura
Post by asdf on Oct 31^st, 2005, 12:24am

Thank You for comments!
I use Assura in grafical mode but the results are the same as in batch mode: I get Spice netlist whan Spectre is selected as the output format.
In my RSF are included the following two commands:

?outputFormat "spice"
?pipeAdvgen "spp -convert -log <cellName>.scs.log"

anyway I get <cellName>.scs file which is Spice format.
I think the convertion is not performed but I cannot understand why.
I also tried to run "spp -convert -log <cellName>.scs.log" command from command line, but I don't get result.

The convertion can be performed bay command
"spp -convert -iofile <inputfile> <outputfile>"
but this command does not work whan included to RSF as a pipe command.

Title: Re: Parasitic extraction with Assura
Post by bernd on Nov 1^st, 2005, 10:19am

If you run Assura in GUI mode out of DFII, may
I asked the question why you try to get a Spectre
netlist rather than use the extracted view?

If you realy neccessarly need a Specte netlist, as
a workaround you can also create an extraced view with Assura, then open it and call the Analog Environment (Artist) out of it and create a Spectre
netlist out of Artist.

Bernd

Title: Re: Parasitic extraction with Assura
Post by asdf on Nov 1^st, 2005, 11:24pm

Thank you Bernd
The extracted view is a solution and another way also exists, but these methods
require additional operations.
so I need to use shorest way to get netlist for saving the time.

Title: Re: Parasitic extraction with Assura
Post by Andrew Beckett on Nov 4^th, 2005, 5:15am

What do you mean these require additional operations? It will be much less work to use an extracted view. Otherwise you need to ensure that you've set up the termOrder in the CDF for the block you're going to simulate with the same order as it appeared in the extracted SPICE or spectre netlist - and that order may vary. It sounds painful to me to use that approach when the extracted view approach is well integrated.

Andrew.