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How to compute the bounding box of a cell in a hierarchical design

Renee

Hi,

 I had some problems with the placing pad head in a chip design. In the orignal design, all IOs have been placed without pad head. As there are so many pads in the design, I tried to realize this function by writing a program.

 Here are the functions it should have:

1. It should be able to identity positions of each IO.

2. It should be able to place pad head to the relative positon.

Here are my general thoughts to realize these function:

1. As there are identify layers covering IO, thus in order to locate them, I could locate bounding box of those ID layers, then I can have the lowerleft and upperight vertexes of IO. (But I have problems with getting bounding box of a cell in a hierarchical design)

2. How to place cell at a specific position in a design automatically?

 Thanks in advance!

Lei  

Parents

  • Do a recursive descent of all the instances in the design, and look for the IO cells at each level. As you descend, you can keep track of the overall transformation (by looking at inst~>transform) and you can then concatenate all the transformations (using dbConcatTransform). You can then use this concatenated transformation to map any coordinates within the IO cell back to the top level cellView, and thus know where to place the "pad heads".

    There are quite a few examples of using recursion to visit all cellViews in a layout on http://support.cadence.com and similarly examples of using dbConcatTransform.

    Regards,

    Andrew.

Reply

  • Do a recursive descent of all the instances in the design, and look for the IO cells at each level. As you descend, you can keep track of the overall transformation (by looking at inst~>transform) and you can then concatenate all the transformations (using dbConcatTransform). You can then use this concatenated transformation to map any coordinates within the IO cell back to the top level cellView, and thus know where to place the "pad heads".

    There are quite a few examples of using recursion to visit all cellViews in a layout on http://support.cadence.com and similarly examples of using dbConcatTransform.

    Regards,

    Andrew.

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