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How to find a closed loop in the routing using some skill script

Amit Biswas

Hi,

I am trying to detect some closed loop in the routing. The formation of the loop can be in multiple layers.

As of now I extracted the signal using DIVA. I have the layout where a particular net routing is ectracted.

Now I would like to check if there is any loop.

For example, when we do decap filling at the top level at the final stage, we try to make very strong and best connection for POWER and GND.

Some times it creates a closed loop and causes lot of other issues. 

Thanks,

Amit

  • Amit,

    Maybe something like this in your Diva rules:

    VDD=geomOr(
      geomGetNet(metal1 "VDD")
      geomGetNet(metal2 "VDD")
      geomGetNet(nwell "VDD")
    )
    VDDwithLoops=geomGetHoled(VDD)
    saveDerived(VDDwithLoops ("intext" "drawing") ext_view) ; ext_view is because I was running this in an extract and wanted the derived layer in the extracted view rather than original layout

    In other words, or together the shapes on a particular net which are connected. 

    Not sure this is necessarily what you want though - I can imagine that you could have horizontal stripes on metal1 and vertical stripes on metal2 which are strapped at one end and the or would make them look like loops... beyond that this probably needs some more thought than I can give right now. Perhaps you should contact customer support?

    Regards,

    Andrew.

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