Testing of interconnections with use of reduced-size signature-based diagnostic dictionary

The paper presents a new method for size reduction of a signature-based diagnostic dictionary that is normally used for testing of static and delay faults in interconnections that are tested by means of an R-LFSR ring register. The newly developed method, similarly to the previous studies of the authors, assume that the n-bit bus under test is split into b fragments with their width of k bits each. Next, each fragment of the bus is tested with use of a separate 2k-bit R-LFSR. This paper, suggests subdivision of the test procedure into four phases and alternate operation of odd and even registers. Such an approach eliminates effect of mutual impact between states of neighbouring R-LFSR's in case of shorts between feedback lines of these registers. These possible interactions were a drawback of previous solutions as they limited the possibility to reduce size of the diagnostic dictionary. Owing to application of this new technique to full detection, localization and identification of all the considered faults that may occur on an n-bit bus, the new solution needs much smaller dictionary, where its size is determined by the multiplicity r of faults within each k-bit fragment, even if the bus width n>>k.