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Method and apparatus for determining the performance of nets of an integrated circuit design on a semiconductor design automation system

  • US 5,469,366 A
  • Filed: 09/20/1993
  • Issued: 11/21/1995
  • Est. Priority Date: 09/20/1993
  • Status: Expired due to Term
First Claim
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1. A method of determining the performance of nets of an integrated circuit design comprising:

  • providing a semiconductor design automation system;

    providing an integrated circuit design on the semiconductor design automation system, said integrated circuit design including a net-list, said net list including a plurality of nets, each net representing a plurality of interconnected first nodes;

    collapsing each net to a corresponding simplified equivalent circuit having a number of simplified nodes less than or equal to the plurality of first nodes represented by the net corresponding to the simplified equivalent circuit; and

    simulating the simplified equivalent circuit for each of the plurality of nets, thereby determining a node voltage waveform for each simplified node of the corresponding simplified equivalent circuit;

    the step of collapsing each net to a simplified equivalent circuit further comprising;

    identifying superbranches of each net, each superbranch including a first subset of the plurality of first nodes, each node in the first subset being a superbranch node;

    collapsing each superbranch of each net to a simplified node;

    identifying generalized superbranches of each net, each superbranch including a second subset of the plurality of first nodes, each node in the second subset being a generalized superbranch node;

    collapsing each generalized superbranch of each net to a simplified node;

    identifying superpaths of each net, each superbranch including a third subset of the plurality of first nodes, each node in the third subset being a superpath node; and

    collapsing each superpath of each net to two simplified nodes;

    each superbranch node having a ground current associated therewith;

    one superbranch node from each superbranch being a superbranch root node, the remaining superbranch node being superbranch child nodes; and

    the step of collapsing each superbranch to a simplified node further comprising repeating, for each superbranch of each net, the steps of;

    determining an effective superbranch root node ground current for the superbranch by totaling the ground currents of each superbranch node in the superbranch;

    eliminating all child nodes of the superbranch; and

    assigning the effective superbranch root node ground current to the superbranch root node;

    until all superbranches have been operated upon.

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