# VLSI Questions and Answers – Test Patterns

This set of VLSI Multiple Choice Questions & Answers (MCQs) focuses on “Test Patterns”.

1. Which method is used to determine structural defects?
a) deterministic test pattern
b) algorithmic test pattern
c) random test pattern
d) exhaustive test pattern

Explanation: Deterministic test patterns are used to detect specific faults or structural faults for a circuit under test.

2. Which is known as the stored test pattern method?
a) deterministic test pattern
b) algorithmic test pattern
c) random test pattern
d) exhaustive test pattern

Explanation: Deterministic test pattern method is also known as stored test pattern method in the context of BIST applications.

3. Which method uses finite state machine for developing the test pattern?
a) deterministic test pattern
b) algorithmic test pattern
c) random test pattern
d) exhaustive test pattern

Explanation: Algorithmic test pattern method uses the hardware finite state machine for generating algorithmic test vectors for the circuit under test.

4. A n-bit counter produces ______ number of total input combinations.
a) 2(n-1)
b) 2(n+1)
c) 2n
d) 2n

Explanation: A n-bit counter produces totally 2n number of all possible input combinations for testing the circuit under test and it is called as exhaustive test pattern method.

5. Exhaustive test pattern determines
a) gate level faults
b) logic level faults
c) functional faults
d) structural faults

Explanation: Exhaustive test pattern method detects all gate level struck-at fault and also bridging fault.

6. Exhaustive test pattern also detects delay faults.
a) true
b) false

Explanation: Exhaustive test pattern method does not detect all transistor level faults or delay faults since those faults needs specific ordering.

7. Which is not suitable for circuits having large N values?
a) exhaustive test pattern method
b) pseudo-exhaustive test pattern method
c) random test pattern method
d) deterministic test pattern method

Explanation: Exhaustive test pattern method is not suitable for circuit having large N values since there is a limit for fault coverage.

8. Which method needs fault simulation?
a) exhaustive test pattern method
b) pseudo-exhaustive test pattern method
c) random test pattern method
d) deterministic test pattern method

Explanation: Exhaustive test pattern method needs fault simulation for determining fault coverage where as pseudo-exhaustive test pattern method does not need fault simulation.

9. In which method sequences are repeatable?
a) exhaustive test pattern method
b) pseudo-exhaustive test pattern method
c) random test pattern method
d) pseudo-random test pattern method

Explanation: Pseudo-random test pattern method have properties similar to random pattern sequence but the sequence are repeatable.

10. Which method is used for external functional testing?
a) exhaustive test pattern method
b) pseudo-exhaustive test pattern method
c) random test pattern method
d) pseudo-random test pattern method

Explanation: Random test pattern method is used for external functional testing of microprocessors as well as in ATPG software.

Sanfoundry Global Education & Learning Series – VLSI.

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