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Virtuoso router leaves steiners, routes & guides in the database

HiuMinor
Hi,

we currently experienced a strange behaviour concening the bounding boxes of routed macros.

First we created a big macro layout using the Virtuoso router. After that we re-used the layout to create some derivates using the Virtuoso layout Editor (actually smaller layouts by deleting parts of the bigger one). All the checks (DRC,ERC,LVS ...) are OK, but the bounding boxes (when instantiating the small macros) are way too large. They still have the size of the original, bigger macro.

When looking into the OA database I found a lot of objects, that seems to be remains from the initial routing of the big macro (steiners, routes & guides). Now I deleted all the objects lying outside the current macros boundary by a SKILL procedure and thus also the bounding box, when instatiating the macro, is OK again.

Now my questions:

  • Can I delete all the steiners, routes & guides, if the routing of a macro is finished, or are these objects in some way relevant for the layout cellView or the final GDS?
  • Is this the normal behaviour of the Virtuoso router to leave these objects in the database, or are they possibly remains of a crash or misuse of the tool?
  • If they can be deleted without any loss of design contents, is it possible to have a clean-up step in the Virtuoso router to get rid of them automatically?

Many thanks in advance, Ronald.

PS: I forgot to mention our tool version: IC6.1.4.500.8

 

Parents
  • Matze17
    Hi Quek and Ronald

    in the CADENCE Doc there is a scenario description when large bounding boxes can occur:

    One more scenario where such an issue ( that means to large Bounding-Boxes ) can happen is when you have steiners in the design. Wire Editor and assisted routing commands like P2P ( Point to Point ), Guided routing and VSR etc use steiner to ease the routing. In general deletion of a net should delete a steiner associated with a net. However, steiners may be leftover in a layout view if wires of a net get deleted due to unspecified reasons but the net was not cleaned up. In such a case one should delete the steiner after finding it out.
    ...

    These logical points ( steiners ) can be regenerated by the routing commands automatically without any user intervention. Starting ISR12 of IC6.1.5 release, when a steiner is connected to a route and we try to move the route, the steiner will move according to the new coordinate of the design or the end elements of the route.

    I also created manually steiners and guides. Both can create large bounding boxes.

    So I would also suggest to delete steiners only

    best regards

     
     

     
Reply
  • Matze17
    Hi Quek and Ronald

    in the CADENCE Doc there is a scenario description when large bounding boxes can occur:

    One more scenario where such an issue ( that means to large Bounding-Boxes ) can happen is when you have steiners in the design. Wire Editor and assisted routing commands like P2P ( Point to Point ), Guided routing and VSR etc use steiner to ease the routing. In general deletion of a net should delete a steiner associated with a net. However, steiners may be leftover in a layout view if wires of a net get deleted due to unspecified reasons but the net was not cleaned up. In such a case one should delete the steiner after finding it out.
    ...

    These logical points ( steiners ) can be regenerated by the routing commands automatically without any user intervention. Starting ISR12 of IC6.1.5 release, when a steiner is connected to a route and we try to move the route, the steiner will move according to the new coordinate of the design or the end elements of the route.

    I also created manually steiners and guides. Both can create large bounding boxes.

    So I would also suggest to delete steiners only

    best regards

     
     

     
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