LFSR‐based generation of boundary‐functional broadside tests

Abstract

This study considers the compression of a type of close-to-functional broadside tests called boundary-functional broadside tests when the on-chip decompression logic consists of a linear-feedback shift register (LFSR). Boundary-functional broadside tests maintain functional operation conditions on a set of lines (called a boundary) in a circuit. This limits the deviations from functional operation conditions by ensuring that they do not propagate across the boundary. Functional vectors for the boundary are obtained from functional broadside tests. Seeds for the LFSR are generated directly from functional boundary vectors without generating tests or test cubes. Considering the tests that the LFSR produces, the seed generation procedure attempts to obtain the lowest possible Hamming distance between their boundary vectors and functional boundary vectors. It considers multiple LFSRs with increasing lengths to achieve test data compression. The procedure is structured to explore the trade-off between the level of test data compression and the Hamming distances or the proximity to functional operation conditions.