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Unformatted text preview: pseudo-exhaustive vectors is simply at most 2 n 1 + 2 n 2 + 2 n 3 . 4.3 THEORETICAL BACKGROUND: BOOLEAN DIFFERENCE Consider the circuit shown in Figure 4.5. Let the target fault be the stuck-at-0 fault on primary input y . Recall the high-level concept of test generation illustrated in Figure 4.1, where the objective is to distinguish the fault-free circuit from the faulty circuit. In the example circuit shown in Figure 4.5, the faulty circuit is the circuit with y stuck at 0. Note that the circuit output can be expressed as a Boolean formula: f = xy + yz Let f ± be the faulty circuit with the fault y/ 0 present. In other words, f ± = f²y = ³´ In order to distinguish the faulty circuit f ± from the fault-free counterpart f , any input vector that can make f ⊕ f ± = 1 would suffice. Furthermore, as the aim is test y f w x z ± FIGURE 4.5 Example circuit to illustrate the concept of Boolean difference....
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- Spring '08