Test Sequence Generation for Sequential Circuits with Distinguishing Sequences


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E76-A    No.10    pp.1730-1737
Publication Date: 1993/10/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
distinguishing sequence,  stuck-at fault,  sequential circuit,  test sequence generation,  design rechnique,  

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In this paper we present a method to generate test sequences for stuck-at faults in sequential circuits which have distinguishing sequences. Since the circuit may have no distinguishing sequence, we use two design techniques for circuits which have distinguishing sequences. One is at state transition level and the other is at gate level. In our proposed method complete test sequence can be generated. The sequence consists of test vectors for the combinational part of the circuit, distinguishing sequences and transition sequences. The test vectors, which are generated by a combinational test generator, cause faulty staes or faulty output responses for a fault, and disinguishing sequences identify the differences between faulty states and fault free states. Transition sequences are necessary to make the state in the combinational vectors. And the distinguishing sequence and the transition sequence are used in the initializing sequence. Some techniques for shortening the test sequence is also proposed. The basic ideas of the techniques are to use a short initializing sequence and to find the order in concatenating sequences. But fault simulation is conducted so as not to miss any faults. The initializing sequence is obtained by using a distinguishing sequence. The efficiency of our method is shown in the experimental results for benchmark circuits.