Robust tests for parity trees

Tests to detect line stuck-at and transistor stuck-open faults in CMOS binary parity trees are considered. The main objective was to derive bounds on test sequences and test sequences that detect all single faults, even in the presence of circuit delays. It is shown that the desired robustness of test requires tests whose lengths are proportional to the depth of the trees under test, in contrast to earlier used tests of constant length, in which robustness was not required. The results derived give exact bounds for complete trees, but similar results for incomplete trees need further investigations