1. Linear feedback shift register occupies more area.
A. true
B. false
Answer: B
The linear feedback shift register method is more area efficient than counters and other methods and requires less combinational logic.
2. In external feedback LFSR, shift registers and feedback paths are combined using
A. OR gates
B. AND gates
C. EX-OR gates
D. NAND gates
Answer: C
In the external feedback linear feedback shift register method, the shift registers, and the feedback path are linearly combined via EX-OR gates.
3. Which uses the highest operating frequency?
A. internal feedback LFSR
B. external feedback LFSR
C. both internal and external LFSR
D. counters
Answer: A
Internal feedback LFSR provides implementation with the highest operating frequency for use in a high-performance applications.
4. Which method has more uniformity?
A. internal feedback LFSR
B. external feedback LFSR
C. all of the mentioned
D. none of the mentioned
Answer: B
External feedback LFSR has more uniformity of the shift register and this is its main advantage.
5. The initial state in LFSR must be initialized to zero.
A. true
B. false
Answer: B
The initial state in LFSR must be initialized to any state other than zero so that it goes through all possible states except all 0’s before repeating the sequence.
6. For n-bit LFSR, the longest possible sequence is given by
A. 2n
B. 2n + 1
C. 2n – 1
D. 1/2n
Answer: C
For n-bit LFSR, the longest possible sequence of patterns is given by 2n-1.
7. ______ 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.
8. 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.
9. 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.
10. 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.
