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Create an alternative pmos/nmos pcell, with all virtuoso functionality

RVERP

Hi,

I want to replace the nmos/pmos of the fab with an alternative pcell I have created myself.

This custom pcell uses the mos pcell, and adds things depending on the parameters I have added. Now I want to use this custom pcell in my layouts, but I also want to use the virtuoso functionality

I should be able to:

  1. Do a gen form source. The new pcell must be used.
  2. Maintain the connectivity.

Things I have so for:

  1. Gen form source: I have changed the physical cell in the physconfig. The gen from source picks the custom cell I want, but the parameters set in the schematic aren't transferred correctly to the new pcell. I have changed my custom pcell so that the names are the same as the ones I see in the cdf.
    Now if I do a gen from source, parrameters are filled in, but the numbers filled in are float (1e5), while in cdf they are a string (10u).
    QUESTION: How are parrameters tranfered to the pcell in a gen from source. Are the always passed as a float? Does this happen in a standard way or is this dependant of the techno?
  2. Maintain connectivity: I suppose adding pins/terminals is enough here. Only I have to have the naming right.
    QUESTION: Is it oke to suppose that these are s d g b by default?

I hope the above description is a bit clear, if not, I am happy to clarify is some more.

  • What are the parameters on the source component in the schematic? Are these float too?

    Adding pins/terminals will be needed. You'll need to call them whatever they are called on the source device. There's no "default" naming for them - it purely depends on what the source device has called them.

    Regards,

    Andrew

  • The numbers in the schematic parameters have the suffix "u" so I suppose they are also a string.

  • I still can't find a way to "replace" a pcell.

    Imagine I have a pcell is generated with generate all from schematic. Then I change the instance lib and cellname so it references to another pcell.

    What is the criterea for a parameter that it can be passed to the new cell? They are already of the same type.

    I can do it with the pcells from the fab (tsmc18), if I change the cellname from nmos to pmos, all the parameters are applied to the new cell. 

  • Update: There is something moving :)

    The values I want to pass between the pcells is width and length. I was using width as a test, and it never did what I wanted. I tried length, and it worked. Width is not working only if the value results in an integer (example width =5u), if the value is a float (width=5.1u), there is no problem. To understand what this is causing, I just know not enough of pcells.

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