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Overlapping Pin layers not triggering abutment.

snee

I have created a PCell of a traditional transistor. Both the Source and Drain is their own ROD object. I have setup the abutment properties according to documentation, however when overlapping one cells source with the others drain the auto abutment function (MosAbutFunc) is never called and the shapes never snap.

The following is how I attach abutment options to the respective Diff layers.

leftObj = leftDrain->dbId
net_id = dbMakeNet( pcCellView "S" )
term_id = dbCreateTerm( net_id "S" "inputOutput" )
pin_id = dbCreatePin( net_id leftObj "leftDiff")
dbReplaceProp(leftObj "abutFunction" "string" "MosAbutFunc")
dbReplaceProp(leftObj "abutAccessDir" "list" list("left"))
dbReplaceProp(leftObj "abutClass" "string" "diffs")
dbReplaceProp(leftObj "vxlInstSpacingDir" "list" list("left") )
dbReplaceProp(leftObj "vxlInstSpacingRule" "float" 2.0)

rightObj = rightDrain->dbId
net_id = dbMakeNet( pcCellView "D" )
term_id = dbCreateTerm( net_id "D" "inputOutput" )
pin_id = dbCreatePin( net_id rightObj "rightDiff")
dbReplaceProp(rightObj "abutFunction" "string" "MosAbutFunc")
dbReplaceProp(rightObj "abutAccessDir" "list" list("right"))
dbReplaceProp(rightObj "abutClass" "string" "diffs")
dbReplaceProp(rightObj "vxlInstSpacingDir" "list" list("right") )
dbReplaceProp(rightObj "vxlInstSpacingRule" "float" 2.0)

  • Hi Shane,

    Are you operating in Virtuoso Layout Suite XL? And do you have the Options -> Editor "Abut Server" turned on, and the XL Options, Generation, "Abut transistors" option turned on? You must be in XL for abutment to work, though unabutment can work in 'L'. Which version are you using? The latest versions have a PCell development mode in Virtuoso that might be helpful in debugging.

    I hope this helps.

    Regards,

    Lawrence.
  • The issue is, I can abut ME1 Drawing layers, but I cannot abut any other layer.

    For example, if I create a MOS device, whos Source/Drain are rod-objects of layer "Diff drawing", abutment will not work. However, if I change the layer in my PCell to "ME1 drawing", for experimentation, abutment works correctly.

    The issue is the Diff layer. What would cause one layer to be abutable, but others not to work?

    Again, this is the same PCell code, just the layers for S/D are redefined.

  • You need pins on diffusion and the abut properties on the pin figures, plus you need the Diff layer to be in the valid layers (i.e. so that VLS XL will extract it - otherwise there's no connectivity on those pins).

    You can check this in VLS XL by first looking at Options->Layout XL, going to the Connectivity Tab and noting the name of the Constraint group used in the Extractable Layers section down the bottom. You could check this using the Process Rule Override tool in the constraint manager, but actually hitting the Diagnostics Report button next to the Extractable Layers section is even easier to see what's enabled...

    Regards,

    Andrew.

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