VLSI Built-in Self Test MCQ Quiz – Objective Question with Answer for Built-in Self Test for VLSI

21. ______ determines the position of the EX-OR gate with respect to flip-flops.

A. maximal length sequence
B. value of n
C. number of flip-flops
D. characteristic equation

Answer: D

The placement of EX-OR gates with respect to the flip-flops in LFSR is determined using the characteristic polynomial equation.

 

22. The zero coefficient terms determine the number of EX-OR gates to be used.

A. true
B. false

Answer: B

The non-zero coefficient in the characteristic polynomial expresses the EX-OR gate in the feedback network.

 

23. LFSR has ______

A. EX-OR gates
B. AND gates
C. OR gates
D. EX-OR and AND gates

Answer: A

LFSR has flip-flops and EX-OR gates and counters have one EX-OR gate and AND gate per flip-flop.

 

24. Primitive polynomials are those

A. which has initial state of zero
B. which gives maximal length sequence
C. which does not give maximal length sequence
D. which has AND gate per flip-flop

Answer: B

Primitive polynomials are those which give maximal length sequence and those which do not give maximal length sequence are called a non-primitive polynomials.

 

25. In LFSR, the test patterns are repeatable.

A. true
B. false

Answer: A

In the linear feedback shift register used to produce pseudo-random patterns, the patterns are deterministically generated and are repeatable.

 

26. Primitive polynomial should have a minimum number of zero coefficients.

A. true
B. false

Answer: A

Primitive polynomials with a minimum number of zero coefficients are the desired characteristic polynomial for the LFSR.

 

27. The minimum number of EX-OR gates used is in between

A. 0 to 2
B. 1 to 3
C. 2 to 5
D. 3 to 7

Answer: B

The minimum number of EX-OR gates used for the linear feedback shift register is between 1 and 3.

 

28. The LFSR takes reasonable time if the n value is

A. below 50
B. below 100
C. below 10
D. below 25

Answer: D

The LFSR’s degree value is limited to 22 to 25 for producing maximal length sequence in a reasonable amount of time.

 

29. Which is used to initialize the LFSRs?

A. zeroes
B. ones
C. preset of flip-flop
D. EX-OR gate

Answer: C

The preset of each flip-flop in LFSR to used to initialize the LFSRs and the initial non-zero coefficient or state ensures maximal length sequence is obtained.

 

30. The beginning and end of the maximal length sequence can be determined using

A. AND gate
B. NAND gate
C. AND or NAND gate
D. Both AND and NAND gate

Answer: C

The beginning and end of the maximal length sequence of the LFSR can be determined using AND gate or NAND gate.

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