Testable Design for Stuck-Open Faults with the Robustness


IEICE TRANSACTIONS (1976-1990)   Vol.E73   No.8   pp.1294-1300
Publication Date: 1990/08/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: Special Section PAPER (Special Issue on Fault-Tolerant Systems)

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Robust test has been proposed to overcome the potential invalidation of the two-patten test due to hazards. However, it is difficult to generate robust test patterns and they may not exist for some stuck-open faults. In this paper, to overcome this difficulty, we propose a new testable design method with the robustness. Since a faulty gate is regarded as a tri-state element, the gate output node can be set to arbitrary logic value from the outside of a circuit. In the proposed method, on the basis of this idea, each output of the gate can be set to any logic value by an extra driver. Then, it is checked what value the output gives. Any stuck-open fault can be detected by one test pattern by this method which can be implemented relatively easily. To reduce the number of observalbe points, we also consider a method for selecting internal observable points without losing the property of the robustness. As a result, output nodes of reconvergent gates are used as internal observable points. Experimental results of the pattern generation for some benchmark circuits are given.