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Virtuoso XL: how to remove instance pin from net?

caver456

I'm using XL layout on a layout that was initially created in L and has no connectivity source.

Most of the layout work for this cell has been completed in L with no connectivity, so, I'm just using XL to create some nets within the already-completed-layout region (by assigning a net name in the Connectivity tab of the Edit Properties form for a shape in the completed area), and add some instance pins from the not-yet-laid-out region (using Connectivity -> Assign) to those nets, to get the flight lines and drag lines.

This is a big help, but, how can I remove an instance pin from a net, i.e. in case I screw up during the assignment?

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  • Marc Heise

    Hi,

    assigning a net to a shape is the last thing you should do. It will create so called "sticky nets" which can disrupt the connectivity.

    Connectivity information should always com from pins or from device terminals. I understand that it seems to be a sweet and easy way
    to fix connectivity but it won't do you much good.

    If you are on IC 6.1.7 you have a good chance to let "Update Binding" do the job for you. It's taking your L-Layout and is trying to map
    devices and nets to the source schematic. It can also remove these "sticky nets", which I would advise to do.
    What you should  do before the auto binding is to have at least the Pins matching between Schematic and Layout, because the tool takes
    them as anchor points to explore the connectivity and repair it.

    To not let your original question unanswered, there is the command "propagate net"in te conectivity-net menu, select an instance and
    hit that command. It lets you manually assign net names to instances terminal.
    Again..try to avoid that..if you can bind the layout instance to a schematic instance the right connectivity information will be transferred to
    the layout terminals.

    Kind regards,

    Marc

Reply
  • Marc Heise

    Hi,

    assigning a net to a shape is the last thing you should do. It will create so called "sticky nets" which can disrupt the connectivity.

    Connectivity information should always com from pins or from device terminals. I understand that it seems to be a sweet and easy way
    to fix connectivity but it won't do you much good.

    If you are on IC 6.1.7 you have a good chance to let "Update Binding" do the job for you. It's taking your L-Layout and is trying to map
    devices and nets to the source schematic. It can also remove these "sticky nets", which I would advise to do.
    What you should  do before the auto binding is to have at least the Pins matching between Schematic and Layout, because the tool takes
    them as anchor points to explore the connectivity and repair it.

    To not let your original question unanswered, there is the command "propagate net"in te conectivity-net menu, select an instance and
    hit that command. It lets you manually assign net names to instances terminal.
    Again..try to avoid that..if you can bind the layout instance to a schematic instance the right connectivity information will be transferred to
    the layout terminals.

    Kind regards,

    Marc

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