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Unformatted text preview: to be very difficult and is vulnerable to many backtracks, leading to excessive exe-cution times. Therefore, it makes sense to include the deterministic algorithm for fault excitation and propagation, while the GA is used for state justification. Note that this approach cannot identify some untestable faults. In GA-HITEC, a fault is taken as a target. Then, the fault is excited by the deterministic engine, followed by propagation to a primary output, perhaps through several time frames, also by the deterministic engine. Through this process, several primary inputs and flip-flop variables at time frame 0 would have been chosen as decision points, as illustrated in Figure 4.46. The decisions made on the flip-flops x 1 x x x 1 x x 10101 00111 11010 Step 1: Deterministic ATPG in time-frame zero to derive a combinational vector Step 2: GA to derive the justification sequence Target State 1 1/0 s-a-0 1 s-a-0 s-a-0 s-a-0 ± FIGURE 4.46 Test generation using GA for state justiFcation....
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- Spring '08