77_pdfsam_VLSI TEST PRINCIPLES & ARCHITECTURES

77_pdfsam_VLSI TEST PRINCIPLES & ARCHITECTURES - 46...

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Unformatted text preview: 46 VLSI Test Principles and Architectures Many methods have been developed to calculate the probability-based testability measures. A simple method is given below, whose basic procedure is similar to the one used for calculating combinational testability measures in SCOAP except that different calculation rules are used. The rules for probability-based controllability and observability calculation are summarized in Tables 2.3 and 2.4, respectively. In Table 2.3, p is the initial 0-controllability chosen for a primary input, where < p < 1. Compared to SCOAP testability measures, where non-negative integers are used, probability-based testability measures range between 0 and 1. The smaller a probability-based testability measure of a signal, the more difficult it is to control or observe the signal. Figure 2.3 illustrates the difference between SCOAP testability TABLE 2.3 Probability-Based Controllability Calculation Rules 0-Controllability (Primary Input, Output, Branch) 1-Controllability (Primary Input,...
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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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