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Is irregular shape LEF possible?

atwork

I have questions about typical LEF generation. 

1. If using virtuso (leftOut) to generate a LEF for top verilog netlist, does it need some modifications for class, site etc?

2. Can the LEF size be irregular? eg, like a L  or U shape.

3. If this particular macro has corner cells, and IO cells included, how to definte them in LEF? Or is it necessary?  Can IO assignemnt file handle a block like this? Any special work? I cannot find useful information from user guide.

Any suggestions welcome ! Thank you.

 

  •  Hi,

    1. I would suggest you to use Abstract Generator in order to set and generate correctly your abstract. If you would liek to do it by hand yes you need to set the class and the type but teh way top do it depends on the Virtuoso version (CDBA/OA)

    2.  You can have a reactilinear prBoundary for your block, a layer OVERLAP describes the piece of teh block which could be covered by other blocks.

    3. Not sure about this part. I woudl suggest to create a BLOCK type of abstract and to place it by hand.

     Thanks,

    Alex

     

     

  • Hi Alex

    I believe the layout person is using IC6.1, and according to him, he only used lefOut wiithout any options.

    First I want to clarify with you. Are you talking about to use OA or to use LEF for SOCE?

    1.

    Personally I am looking at this abstract generator manual from support web. But I do not find it is useful to problem. From your reply, my impression is Virtuso can write out a LEF with proper syntax in it. Is this correct?

     2.

    I also looking at LEF/DEF language reference from support site but I cannot find syntax for prbounday. Is this for Virtuso?

    3.

    I am thinking to define macro as class pad. But I am not sure at this moment. I need to experiment.

    Do you have any documents or user guides for the related issues?

    Thanks 

  •  Hi,

    I'm talking about LEF and OA as you can use both in Encounter and you can easily export a LEF from Virtuoso on OA.

     1.  Virtuoso can write LEF with proper syntax if you original view contains the right info. Did you have already an 'abstract' view ? if you have one How did you generate it ? If you dfon't have this is where Abstract Generator could be useful.

    2. You are correct teh prBoundary is in Virtuoso and it will represent the 'SIZE' in LEF.

    3. This is up to you

    I think thsi link could help in order to understand what type of info are needed on top of the view you would liek to export through LEF.

    http://support.cadence.com/wps/mypoc/cos?uri=deeplinkmin:DocumentViewer;src=pubs;q=/soceUG/soceUG9.1/dmsflow.html#9051048

    Thanks,
    Alex

  • Hi Alex

    I do not use Virtuso or Abstract Generator at all.

    Layout person provides the LEF and OA to me.

    The LEF he provided was missing information for loading into SOCE.

    The information such as SITE, CLASS, SIZE, Symmetry etc were not in his LEF. And he insisted this is correct for SOCE.

    The brings up to my original question. Are there any manual modifications needed for the LEF from Virtuso?

    In the link, you sent me. It shows some required syntax must be in the LEF for SOCE. My impression now is that Virtuso or abstract generator can generate all the required information. Is this right?

    One additional question I have, even thought the user guide says it is prohibited to mix LEF and OA. 

    But can I use OA for one special marcor but regular LEF from TSMC for standard cells, IO/PAD cells?

    Thanks

  • Hello,

    No modification of LEF coming from Virtuoso is normaly required if the view in OA has all the correct settings.

    Virtuoso and Abstract Generator can generate all the needed information in case the original view in OA contains all teh required settings.

    The LEF generated out of Virtuoso should be Encounter compatible if all settings are tehre in OA.

     I think some modifications are needed to be done inside Virtuoso.

     Thanks,

    Alex

     

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