108VLSI Test Principles and Architecturesand should be caught prior to physical implementation. Fault simulation, on theother hand, is concerned with the behavior of fabricated circuits as a consequenceof inevitable fabrication process imperfections. Manufacturing defects (e.g., wireshorts and opens), if present, may cause the circuits to behave differently from theexpected behavior. Fault simulation generally assumes that the design is function-ally correct.The capability of fault simulation to predict the faulty circuit behavior is of greatimportance for test and diagnosis. First, fault simulation rates the effectiveness ofa set of test patterns in detecting manufacturing defects. The quality of a test set isexpressed in terms offault coverage, the percentage of modeled faults that causesthe design to exhibit observable erroneous responses if the test set is applied. Inpractice, the designer employs thefault simulatorto evaluate the fault coverage
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The Circuit, Electronic design automation, Electronic design, Fault coverage