44_pdfsam_VLSI TEST PRINCIPLES & ARCHITECTURES

44_pdfsam_VLSI TEST PRINCIPLES & ARCHITECTURES - of ten...

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Introduction 13 TABLE 1.1 ± Truth Tables for Fault-Free and Faulty Circuits of Figure 1.7 x 1 x 2 x 3 000 001 010 011 100 101 110 111 y 0 1 0 0 0 1 1 1 a SA0 0 1 0 0 0 1 0 0 a SA1 0 1 1 1 0 1 1 1 b SA0 0 1 0 1 0 1 0 1 b SA1 0 0 0 0 1 1 1 1 c SA0 0 0 0 0 0 0 1 1 c SA1 1 1 0 0 1 1 1 1 d SA0 0 1 0 0 0 1 0 0 d SA1 0 1 0 0 1 1 1 1 e SA0 0 1 0 1 0 1 1 1 e SA1 0 0 0 0 0 0 1 1 f SA0 0 0 0 0 0 0 1 1 f SA1 0 1 0 1 0 1 1 1 g SA0 0 1 0 0 0 1 0 0 g SA1 1 1 1 1 1 1 1 1 h SA0 0 0 0 0 0 0 1 1 h SA1 1 1 1 1 1 1 1 1 i SA0 0 0 0 0 0 0 0 0 i SA1 1 1 1 1 1 1 1 1 The truth table entries where the faulty circuit produces an output response different from that of the fault-free circuit are highlighted in gray. As a result, the input values for the highlighted truth table entries represent valid test vectors to detect the associated stuck-at faults. With the exception of line d SA1, line e SA0, and line f SA1, all other faults can be detected with two or more test vectors; therefore, test vectors 011 and 100 must be included in any set of test vectors that will obtain 100% fault coverage for this circuit. These two test vectors detect a total
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Unformatted text preview: of ten faults, and the remaining eight faults can be detected with test vectors 001 and 110; therefore, this set of four test vectors obtains 100% single stuck-at fault coverage for this circuit. Four sets of equivalent faults can be observed in Table 1.1. One fault from each set can be used to represent all of the equivalent faults in that set. Because there is a total of ten unique faulty responses to the complete set of input test patterns, then ten faults constitute the set of collapsed faults for the circuit. Stuck-at fault...
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This note was uploaded on 05/16/2011 for the course ENGINEERIN mp108 taught by Professor Elbarki during the Spring '08 term at Alexandria University.

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