We investigate the benefit of inserting observation points in a circuit in order to improve its diagnostic resolution. The insertion of the points is done so that each fault has a unique signature on these points under at least one of the applied test patterns. The observation points are scan-like elements that serve as test-phase outputs and can be organized in and observed through one or multiple chains. Experimental results show good tradeoffs between number of observation points that need to be inserted and diagnostic resolution achieved.

We propose an innovative scheme for LFSR reseeding based on the efficient generation of the seeds of any non-primitive irreducible polynomial. The scheme has very small hardware overhead irrespective of the number of seeds and guarantees that the generation of the pattern subsequence from each seed is disjoint. Experimental results demonstrate the potential of the mechanism for pseudorandom test pattern generation in a parallel chain test-per-scan environment.