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Limitations

The break extractor uses a two-pass plane-sweep algorithm which sacrifices some accuracy for the sake of speed. As a result, there are several circuit configurations for which the extractor cannot construct a graph. This is a result of the fact that the break extractor actually constructs two graphs for each node in the circuit, one for each sweep. These graphs are them merged in the final graph that is used to create break fault primitives.

There are a few cases where Carafe will introduce a small error in the critical area of a break. This is because the plane-sweep algorithm it uses actually models a defect more like a very thin line (the sweep line) breaking an LW across its width than a circular spot defect.

Broken well contacts are not reported as no change in logical function results.

There are several additional limitations which appear when running in Hemlock mode because the break extractor does not make subcell connections the same way the circuit extractor does.



next up previous contents
Next: Output Files Up: Breaks Previous: Critical Area Calculation



David Dahle Wed Jan 24 11:51:06 PST 1996