Methods, apparatus and computer program products for determining equivalencies between integrated circuit schematics and layouts using color symmetrizing matrices

摘要

A layout versus schematic (LVS) comparison tool determines one- to- one equivalency between an integrated circuit schematic and an integrated circuit layout by performing operations to generate color symmetrizing matrices corresponding to respective child cells in the integrated circuit schematic. Here, the child cells are characterized as having a number of symmetrical configurations which at a port level are electrically equivalent. Operations are also performed to generate a first color symmetry vector for a child cell in the integrated circuit schematic and a second color symmetry vector for the corresponding child cell in the integrated circuit layout. A vector equivalency is also preferably determined by comparing a product of the color symmetrizing matrix and the first color symmetry vector against a product of the color symmetrizing matrix and the second color symmetry vector. Notwithstanding the presence of a vector equivalency, a possibility may still exist that with respect to the corresponding symmetric child cells in the schematic and layout, isomorphism between the schematic and layout is not present. To address this possibility, an operation is preferably performed to detect the absence of a spurious symmetry in the color symmetrizing matrix. If an absence is detected, the presence of the vector equivalency will unequivocally establish the one-to-one correspondence with respect to the child cells being analyzed. Thus, the need to perform a computationally expensive membership test to determine whether a selected permutation can be derived from valid symmetries, can be successfully eliminated. The preferred comparison tool also infers symmetries, where available, so that symmetries of a child cell may be propagated to a parent cell when the tool is evaluating a grandparent cell containing the parent cell.