Method for automated placement of cells in an integrated circuit layout
AssigneeConexant Systems, Inc.
InventorsFlorin Balasa, Koen Lampaert
Life of this patent
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Abstract
An automated method for packing cells in the generation of an integrated circuit design layout that is especially useful for circuits having symmetry constraints, which is the case for most analog circuits, uses sequence pair encoding and simulated annealing. From the set of all cells needed to implement the circuit, subsets of the cells are defined that must exhibit symmetry. Symmetry constraints are defined for each subset and the cells are encoded as ordered sequence-pairs. To reduce the solution space, the initial sequence pair encoding is required to be symmetry-feasible and the annealer subspace is limited to symmetry-feasible sequence-pairs.
Claims20
A method for the automated packing of an integrated circuit layout having a plurality of cells, the method comprising the steps of:
- identifying from the plurality of cells a subset of cells for which substantial symmetry is desired;
- defining symmetry constraints for the subset;
- encoding the packing of the cells as ordered sequence-pairs;
- and
- optimizing the encoding using simulated annealing subject to the symmetry constraints.
A method for the automated placement of a plurality of cells in an integrated circuit layout, the method comprising the steps of:
- identifying from the plurality of cells a subset of cells for which substantial symmetry is desired;
- defining symmetry constraints for the subset;
- representing the plurality of cells in a topological representation subject to the symmetry constraints;
- and
- optimizing the representation by a stochastic technique, maintaining the symmetry constraints during the optimization.
A method for the automated design of an integrated circuit layout wherein the circuit comprises a plurality of cells, the method comprising the steps of:
- identifying from the plurality of cells a first subset of cells that must exhibit symmetry;
- defining symmetry constraints for the first subset of cells;
- identifying from the plurality of cells a second subset of cells that must exhibit matching;
- defining matching constraints for the second subset of cells;
- representing the placement configurations of the plurality of cells as sequence-pair topological representations subject to the symmetry constraints and the matching constraints;
- optimizing the placement configurations using simulated annealing;
- and restricting the annealing to only those configurations that are both symmetry feasible and matching feasible.
A method for the automated design of an integrated circuit layout wherein the circuit comprises a plurality of cells, the method comprising the steps of:
- identifying from the plurality of cells a first subset of cells that must exhibit symmetry with respect to a first axis of symmetry;
- defining first symmetry constraints for the first subset of cells;
- determining a sequence-pair encoding of the cells that meets the first symmetry constraints;
- and
- restricting exploration of further encodings of the cells to a subspace containing symmetry-feasible sequence-pairs.
Dependencies are inferred from the claim text.