Patent ID: 6697980
Filing Date: 2004-02-24
Classification: G01R

Abstract:
A method for choosing internal nodes in a die to be coupled to input ports of an XOR network for fault coverage; the die having input ports, output ports, and an original functional relationship among the input ports, output ports, and internal nodes; the method comprising, in sequence:(1) testing the internal nodes for fault coverage; (2) based upon the testing of (1), generating a set N of nodes that were toggled but not observed; (3) partitioning the set N into subsets of nodes belonging to a test hierarchy indexed by an index i; and (4) choosing a largest subset S(i) in the test hierarchy of index i, and choosing two sets of nodes A(i) and B(i), where A(i) is the set of nodes belonging to the set Sâ€³(i) that are driven by at least one cell not in Sâ€²(i) or that are driven by at least one input port of the die, and B(i) is the set of nodes belonging to the set S(i) that drive at least one cell not in Sâ€²(i), where Sâ€²(i) is the minimum set of cells necessary to maintain the original functional relationship for all nodes in the set S(i), and Sâ€³(i) is the set of nodes that are driven by at least one cell in Sâ€²(i) or that drive at least one cell in Sâ€²(i).