Estimating testing effectiveness of the circular self-test path technique

The effectiveness of a random built-in self-test technique for VLSI circuits is studied. This technique, called the circular self-test path (CSTP), is applicable to circuits that consist of combinational blocks and registers. In particular, the effectiveness of test pattern generation, the effectiveness of test response compaction and fault coverage are examined. The test generation effectiveness is evaluated by the fraction of all possible test patterns applied during a testing session to the circuit under test. The compaction effectiveness of the CSTP technique is measured by the probability of aliasing, and fault coverage by the fraction of all permanent faults that are detected. For all these measures, simple formulas are developed, which give very accurate estimations without detailed circuit simulation. To demonstrate their accuracy, the estimates obtained by the formulas are compared to the results obtained by extensive simulation experiments