Bridging Faults vs Stuck At Faults
Manufacturing defects in dense silicon often manifest as unintended shorts between adjacent signal lines rather than clean stuck-at failures.
The schematic shows a combinational logic block where two internal wires, W1 and W2, run parallel to each other. A bridging fault exists between W1 and W2 that behaves as a wired-AND: if either wire is driven to logic 0, both wires resolve to logic 0 regardless of the other driver. Wire W1 is driven by an AND gate with inputs A and B. Wire W2 is driven by an OR gate with inputs C and D. Output Y1 is directly connected to W1, and output Y2 is directly connected to W2.
Determine the specific test vectors required to sensitize and observe this bridging fault. Identify how this physical failure mode requires different detection strategies compared to standard single stuck-at fault models.
Constraints
- Inputs
A,B,C, andDare standard boolean values. - The bridging fault strictly acts as a wired-AND, pulling the high line low.
- A test vector successfully detects a fault only if the faulty circuit output differs from the good circuit output.
Topics
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