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MOS area and perimeter are not calculated from parametrized w and l

joliveros

Hi all..

In my design I'm using nmos4 and pmos4 active devices from AMS DKIT 3.70 PRIMLIB library. As shown in the figure, when I try to edit their properties in Virtuoso Schematic, their area and perimeter fields are recalculated for w and l values (and are not editable for that reason). So, there is no problem when I assign numerical values to w and l, but when I parametrize those variables (to do parametric analysis with the Analog Environment or to pass symbols parameters down through design hierarchy with "pPar") the area and perimeter values are miscalculated. In fact, they are not recalculated, and the last calculated numerical values remain fixed regardless the actual value the parameters take. I guess this is really no a Cadence issue, but a DKIT one. However, I need to get around this inconvenient and I don't know how to do that.

Thanks in advance for your help.

Parents

  • Base CDF is saved in the cell's prop.xx (or data.dm in OpenAccess-based releases) or library's prop.xx (or data.dm) if it is library CDF rather than cell CDF. This is the "property bag" used for cell and library meta data.

    User CDF is not saved to disk. Effective CDF is just the Base CDF masked by User CDF; any changes you make to the Effective CDF are actually stored in the User CDF.

    You could dump the CDF using the SKILL cdfDump() function. You should be careful though within dumping it and loading it to the new PDK, because you may lose additional parameters which have been added in the new PDK. So you may be better off doing a cdfDump() from both your modified PDK, and the new PDK, and comparing them (with diff?) to see what changed.

    Migrating a design to  OpenAccess is relatively straightforward; there's a utility in the Tools->Conversion Toolbox in IC613 to do this (or you can use cdb2oa at the command line). You should read the Virtuoso Design Environment Adoption Guide in cdnshelp in IC613, which can also be found at <IC613instDir>/doc/dfoaAdopt/dfoaAdopt/pdf . If you're going to do this, you'll be best if the PDK you're going to use is developed/supported on IC613, because migrating a PDK yourself is not something we would normally recommend (although in many cases it works fine).

    Regards,

    Andrew.

Reply

  • Base CDF is saved in the cell's prop.xx (or data.dm in OpenAccess-based releases) or library's prop.xx (or data.dm) if it is library CDF rather than cell CDF. This is the "property bag" used for cell and library meta data.

    User CDF is not saved to disk. Effective CDF is just the Base CDF masked by User CDF; any changes you make to the Effective CDF are actually stored in the User CDF.

    You could dump the CDF using the SKILL cdfDump() function. You should be careful though within dumping it and loading it to the new PDK, because you may lose additional parameters which have been added in the new PDK. So you may be better off doing a cdfDump() from both your modified PDK, and the new PDK, and comparing them (with diff?) to see what changed.

    Migrating a design to  OpenAccess is relatively straightforward; there's a utility in the Tools->Conversion Toolbox in IC613 to do this (or you can use cdb2oa at the command line). You should read the Virtuoso Design Environment Adoption Guide in cdnshelp in IC613, which can also be found at <IC613instDir>/doc/dfoaAdopt/dfoaAdopt/pdf . If you're going to do this, you'll be best if the PDK you're going to use is developed/supported on IC613, because migrating a PDK yourself is not something we would normally recommend (although in many cases it works fine).

    Regards,

    Andrew.

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