270_pdfsam_VLSI TEST PRINCIPLES & ARCHITECTURES

270_pdfsam_VLSI TEST PRINCIPLES & ARCHITECTURES -...

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Test Generation 239 Steady 1 ± FIGURE 4.52 Slow-to-rise transition at the input of an OR gate. Steady 1 a b ± FIGURE 4.53 Slow-to-fall transition propagation example. Proof Consider the circuit shown in Figure 4.53. A slow-to-fall transition fault at a is propagated to the primary output and hence detected, but neither path from a to b is robustly or nonrobustly testable due to off-path inputs at gate b . The two above lemmas conclude that both the launching and propagation of a transition fault can be done through multiple paths and none of the paths may be tested robustly or nonrobustly [Gupta 2004]. Hence, there are some faults that can be missed by the path-delay fault model and can only be captured by the transition
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Unformatted text preview: fault model. But, for small delay defects, an enhanced transition fault model is needed to properly address the aforementioned issues. Transition tests can also be applied in three different ways as for the other delay fault models discussed earlier: launch-on-capture , launch-on-shift , and enhanced-scan . As with path-delay tests, because both launch-on-capture and launch-on-shift place constraints on what the second vector can be, they will achieve lower transition fault coverage when compared with enhanced-scan....
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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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