VLSI testing and testability MCQ Quiz – Objective Question with Answer for VLSI testing and testability

21. D-algorithm is based on

A. existence of one fault machine
B. existence of one good machine
C. existence of one fault and one good machine
D. existence of two fault machines alone

Answer: C

D-algorithm is based on the hypothesis of the existence of two machines – one good machine and one faulty machine.

 

22. The existence of a fault in the faulty machine causes a discrepancy in the behavior of the circuit for all values on inputs.

A. true
B. false

Answer: B

The existence of a fault in a faulty machine causes a discrepancy in its behavior and that of the good machine for some particular values of inputs.

 

23. In D-algorithm, the discrepancy is driven to _____ and observed and thus detected.

A. all inputs
B. particular inputs
C. output
D. end of the circuit

Answer: C

In D-algorithm, a systematic means is provided to drive the discrepancy to output and it is observed and detected.

 

24. D-algorithm is time-intensive for large circuits.

A. true
B. false

Answer: A

D-algorithm is extremely time-intensive and computing-intensive for large circuits and many modifications and improvements are done.

 

25. Sequential circuits are represented as

A. finite state machine
B. infinite state machine
C. finite synchronous circuit
D. infinite asynchronous circuit

Answer: A

Sequential circuits are represented as finite state machine and may be modeled as combinational logic.

 

26. Sequential circuit includes

A. delays
B. feedback
C. delays and feedback from the input to output
D. delays and feedback from output to input

Answer: D

A sequential circuit includes a set of delays and feedback from output to input and it is known as a finite state machine.

 

27. Which constitutes the test vectors in sequential circuits?

A. feedback variables
B. delay factors
C. test patterns
D. all input combinations

Answer: A

The ‘m’ feedback variables constitute the state vector and determine the maximum number of finite states which may be assumed by the circuit.

 

28. Outputs are functions of

A. present state
B. previous state
C. next state
D. present and next state

Answer: A

The next state and output are both functions of the present state and the independent inputs.

 

29. Which are the delay elements for the clocked system?

A. AND gates
B. OR gates
C. Flip-flops
D. Multiplexers

Answer: C

In clocked systems, the basic delay elements are flip-flops and in asynchronous circuits, the delays may be contributed by circuit propagation delays.

 

30. Which contributes to the necessary delay element?

A. flip-flops
B. circuit propagation elements
C. negative feedback path
D. shift registers

Answer: B

The circuit propagation delays contribute to the necessary delay elements. The delay in the feedback path may be non-existence.

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