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Unformatted text preview: 1 ECE52 Spring 11 Lecture 40 4/22/11 Final: Thursday 5/5/11 912AM: Open book, open notes, a few copies of open PowerPoint, closed internet Billionth digit of pi… 2 Path sensitization: example • Sensitize path from input w 1 to output f • i.e. set other inputs such that changing w 1 changes f. The circuit is now sensitized to w 1 at f. w 1 =1 → f=0; w 1 =0 → f=1. • AND/NAND: other inputs 1; OR/NOR: other intputs 0. f a b c w 1 w 2 1 = w 3 0 = w 4 1 = 3 Faults along the path will be detected • a/0 will cause f=1 when w 1 =1 • similarly b/0 and c/1 • a/1, b/1, c/0 all detected by w 1 =0 • Number of paths is typically much less than number of wires, so useful start to an algorithm f a b c w 1 w 2 1 = w 3 0 = w 4 1 = 4 Path analysis • 5 paths: w 1 , w 3 , and w 4 each have one way to reach f; w 2 can reach f via c or bd. • w 1cf: w 2 =1, w 4 =0 (w 3 =x). Tests 01x0, 11x0 • w 2cf: Tests 1000, 1100 • w 2bdf: 0010, 0110 • w 3df: x000, x010 • w 4f: 0x00,0x01 • 10 tests, exploit repeats and dont’ cares to get list down to 6 f b c d w 1 w 2 w 3 w 4 5 Path analysis • 5 paths: w 1 , w 3 , and w 4 each have one way to reach f; w 2 can reach f via c or bd....
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 Spring '11
 Dr.JonathanBoard
 Linear feedback shift register, Path Sensitization, high fanin gates

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