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how to pass CDF parameter's value of an instance in schematic pcell to CDF parameter of schematic pcell

patwardg

An explanation of the problem I am facing is in order -

I have created a schematic pcell (A) in which I am instantiating the instance of a foundry delivered pcell (B). There are some independent (e.g. Bp, Bq ) and some dependent CDF parameters (e.g. Bx) defined for the CDF  of the pcell B.

So, Bx = FB_callback(Bp Bq)

Bx is calculated whenever I change Bp or Bq, using a call back function which I have absolutely no access to.

I have created 2 independent CDF  parameters for A (which is the pcell I created) - Ap and Aq. In the code for my schematic pcell I pass these values Ap and Aq to Bp and Bq respectively. Something like this -

master_b = dbOpenCellViewByType( "foundry_library" "foundry_cell_B" "symbol" )
inst_b = dbCreateInst( pcCellView master_b "I_B" list( 0.0 0.0 ) "R0")
inst_b~>Bp = Ap
inst_b~>Bq = Aq

However, after this when I print out the inst_b~>Bx then I see that it is not getting changed and is always the default.

How do I make sure that the callback routine for the foudry cell gets called? Also how do I pass the new value of Bx back into my pcell's CDF Ax?

Thanks,

Parents

  • I don't really understand. The schematic pcell will receive the pcell parameters (which will probably correspond to CDF parameters), and then it can operate on those. It wouldn't access the CDF of the cell. It's quite right that cdfgData should not be defined. So I'm not really sure what you're trying to do and what you are expecting to work - can you describe this carefully (ideally with the code that isn't working)?

    Thanks,

    Andrew.

     

Reply

  • I don't really understand. The schematic pcell will receive the pcell parameters (which will probably correspond to CDF parameters), and then it can operate on those. It wouldn't access the CDF of the cell. It's quite right that cdfgData should not be defined. So I'm not really sure what you're trying to do and what you are expecting to work - can you describe this carefully (ideally with the code that isn't working)?

    Thanks,

    Andrew.

     

Children
  • in reply to Andrew Beckett

    Hi Andrew, thank you for your previous reply. Actually I encounter the same issue as .

    The problem is, for example, Foundry PDK resistor only provide parallel multi-link, refuse to provide serial multi-link pcell.
    Foundry's reason is, parallel multi-link res is multiple-instance inherently, but serial multi-link is single-instance, which is not good for layout matching, so we disable it.
    Foundry suggested workaround is to use bus connection for serial connection of resistor, which results in complex schematic, and error-prone net label.

    But actually another foundry can provide both parallel and serial multi-link, each configuration support both single-instance (for layout simplicity) and multiple-instance (for more custom layout better matching).

    I want to create a pcell to instantiate foundry resistor in serial multi-link configuration. I tried the SKILL code provided in another webpage
    https://community.cadence.com/cadence_technology_forums/f/custom-ic-design/40177/changing-the-number-of-series-instances-in-a-schematic# 
    And use CCSinvokeInstCdfCallbacks(instID ?callInitProc t ?useInstCDF nil) to update child pcell r value after wrapper pcell w & l change.

    *** Finally the question, how can I pass child pcell dependent CDF value r, to this wrapper pcell CDF?  ***
    So that when I instantiate the wrapper pcell, it can dispplay w & l & and also r, just like foundry pcell.
    So that I can see the r value of child pcell, without the need to decend into the wrapper pcell.

    Or the question can be in a simpler form, how can I mirror CDF display of child pcell to pcell wrapper. From design geometry, to back annotation operating point.

    Sorry the question is long and complex. Thanks, and best regards.

  • in reply to Garrett Zhou

    You should ask this as a new thread rather than adding onto the end of a 9 year old question. Please do that rather than confusing the original thread (please see the forum guidelines - you can always include a hyperlink to this thread for reference).

    Andrew

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