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modified Pcell has no parameter

XZ202601196340

hello everyone.
Thanks for reading this and i really appreciate any help.

i am trying to modify a Pcell from a PDK. I followed this (SKILL: How to recreate/modify an existing PCell and also generate SKILL code for a schematic, layout PCell from an existing schematic) post and did the following steps:

my goal is to remove some metal from the layout of the Pcell and here is what i did:

1. open the Pcell layout and do cvID=geGetEditRep() 

2. Use the dbDumpPcell(cvID "pcell_src.il" "proc_src.il") procedure to dump the existing PCell.

3. Make the desired changes in the output files generated, and name them pcell_mod.il and proc_mod.il.

4. Backup/delete the existing PCell layout cellview.
5. load("pcell_mod.il")

6. Open the newly generated layout cellview. it is asking to update connectivity and there is no schematic in the cell, only spectre, aucdl and symbol so i didnt update anything.
7. Get the cellview ID. cvId=geGetEditRep()

8. dbDefineProc(cvId "proc_mod.il"); changes the layout cellview to be a parametrized cell.

9. when trying to save the updated layout pcell, i chose to save it as transistor but the hierarchy pcell generator says There is no parameter in this cell, continue to compile? i knew something was wrong but i chose yes regardless

and now the shapes in the layout cell do not have ROD associated with them and whenever i try to create an instance of this pcell, it does not scale with my parameter (e.g. i put in width/length and the generated layout does not change)

i m wondering what could go wrong. i also tried not modifying the pcell_src and proc_src and just load them but still, it is not scaling based on my parameter. i m using IC23.


any help is appreciated.


  • Andrew Beckett

    The instructions are a bit unclear in that article, to be honest. Some suggestions based on the experiments I just performed:

    6. When you try to open it, it prompts for the schematic source (because layout is Layout XL in IC23.1). Simply uncheck the schematic source - that would be OK.

    9. Rather than pressing the save button on the layout editor, I suggest you use:
        dbSave(cvId)
        (i.e the same variable you used the geGetEditRep/geGetEditCellView for). 

    That worked for me. I think it's confusing it with the graphical PCell system (because of opening up the Pcell in edit mode). Personally I would have changed:

    1. Open the Pcell in readonly mode and then do cvID=geGetEditCellView()
    2-5. As before
    6. cvId=dbOpenCellViewByType("libName" "cellName" "viewName" "" "a") ; rather than opening in a layout editor
    7. skip this
    8. As before call the dbDefineProc
    9. dbSave(cvId)

    Andrew

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