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I think the short isolation is mainly designed to show the most direct path between two different text labels.
In the illustration below (you may need to click on the green line to expand the picture), I sketched a situation where NET1 and NET2 could be viewed as shorted together through 3 different paths. In that case the fix would be to report all 3 paths so that the layout could be broken in 3 places at the blue lines.
But I think it might also be viewed as a single short that could be solved by making a cut at the red line.
I'm not sure if this applies directly to your situation but I thought it might be a starting point for you and me and hopefully others to describe their experiences and expectations regarding short isolation.
Are you using Calibre version 2009.2 or higher? There is an ACCUMULATE option available in those versions that may help with what you need. If you try that would you let us all know if it helped or not?
Thank you for taking the time to respond and replying back so fast. I agree with your comment regarding short isolation showing the most
direct path between two different labels.
Thanks for the sketch. This is quite helpful in explaining my issue. As you've shown in the sketch, 3 shorts. I would like to be able to see these
3 shorts in the same DESIGNrev session. You mentioned the fix would be to report all 3 paths. What needs to be done so that the 3 paths are
reported? An additional option(s) during the Calibre LVS extraction? If I have other unrelated vdd to vss shorts, I'd like these all to be reported so
I could go through them the same way we go through DRC violations.
I am currently using Calibre version v2008.1_34.24.
I don't think there are any options available in 2008 to change the behavior. It's my belief that in a case represented by the sketch, Calibre will only report the shortest path and that this is by design.
I don't have experience with the ACCUMULATE option in 2009.2 so I can't be sure how that would affect the results in your case, though I would be interested to know in case you find out.
Thanks for your help. I will let you know if I use the ACCUMULATE option in 2009.2 .