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Unformatted text preview: is detectable, it must be excited and propagated to at least one primary output, as illustrated in Figure 4.4. It is clear that all the primary inputs necessary to excite f and propagate the fault-effect must reside in the cone of the output to which f is detected. Thus, the detection probability for f is at least ± ³ 5 ² m , where m is the number of primary inputs in the cone of the corresponding primary output. Taking this concept a step further, the detection probability of the most difficult fault can be obtained with the following lemma [David 1976] [Shedletsky 1977]. Lemma 1 In a combinational circuit with multiple outputs, let n max be the number of primary inputs that can lead to a primary output. Then, the detection probability for the most difficult detectable fault, d min , is: d min ≥ ± ³ 5 ² n max Proof The proof follows from the preceding discussion....
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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.
- Spring '08