251. The primitive polynomial has a property according to which the runs of 1s ______ to runs of 0s.
A. equal
B. greater
C. lesser
D. not related
Answer: A
The primitive polynomial has a property of randomness according to which the runs are equal to runs of 0s.
252. The total number of runs is given mathematically as
A. 2n
B. 2(n-1)
C. 2(n+1)
D. 2n-1
Answer: B
The total number of runs is given as 2(n-1) which is the total number of transitions from 1 to 0 or from 0 to 1.
253. ______ of the runs will have a length of 1.
A. one third
B. one fourth
C. half
D. one eight
Answer: C
The length of the runs is distributed as – half of the runs have length 1, a quarter with length 2, an eight-length 3 and a sixteenth length 4, and so on.
254. The length of the runs is dependent on whether the LFSR is internal or external feedback.
A. true
B. false
Answer: B
The length of the run is independent of whether the LFSR is internal or external feedback and LFSR is also known as a pseudo-random pattern generator.
255. Which process is used to develop the LFSR method?
A. random method
B. gaussian method
C. deterministic method
D. Bernoulli method
Answer: D
Bernoulli method is used in modeling the linear feedback shift register testing method and this is called as random pattern generation method.
256. Cellular automata produce
A. exhaustive patterns
B. exhaustive pseudo-random patterns
C. random patterns
D. pseudo-random patterns
Answer: D
Cellular automata are similar to the linear feedback shift register and it generates pseudo-random patterns.
257. In which method the effect of bit shifting is not observed or visible?
A. internal feedback LFSR
B. external feedback LFSR
C. cellular automata
D. counters
Answer: C
The effect of bit shifting is not observed in cellular automata as it is done in the linear feedback shift register.
258. The patterns produced using ______ is less random.
A. LFSR
B. Cellular automata
C. NAND gates
D. Shift registers
Answer: A
The patterns produced by cellular automata are more random in nature than those produced using LFSR.
260. Which method needs more number of EX-OR gates?
A. internal feedback LFSR
B. counters
C. external feedback LFSR
D. cellular automata
Answer: D
The construction of cellular automata is not as simple as LFSR and thus cellular automata need more EX-OR gates.
261. The construction of the CA register is based on
A. logical relationship of flip-flop
B. EX-OR gate
C. primitive polynomial
D. degree of the polynomial
Answer: A
The construction of cellular automata is based on the logical relationship of each flip-flop to its two neighbors.
262. The next state for rule 150 is obtained by
A. x(t)
B. x(t+1)+x(t)+x(t-1)
C. x(t+1)+x(t-1)
D. x(t)+x(t-1)
Answer: B
The next state for rule 150 is obtained by exploring three current state values – itself, previous flip-flop, and next flip-flop.
263. The next state for rule 90 is obtained by
A. x(t)
B. x(t+1)+x(t)+x(t-1)
C. x(t+1)+x(t-1)
D. x(t)+x(t-1)
Answer: C
The next state for rule 90 is obtained by exploring two current values – the state value of the previous and the next flip-flop.
264. Which occupies a lesser area?
A. internal feedback LFSR
B. external feedback LFSR
C. null condition CA
D. cyclic boundary CA
Answer: D
The area occupied by null boundary cellular automata is comparatively lesser than that used by cyclic boundary CA.
265. The maximal length sequence is given by
A. 2n
B. 2n + 1
C. 2n – 1
D. 2n
Answer: C
The maximal length sequence is given by 2n – 1 in null condition boundary cellular automata.
266. Rule 90 CA minimizes area when compared to rule 150.
A. true
B. false
Answer: A
Maximizing the use of rule 90 cellular automata minimizes area overhead when compared to using rule 150 cellular automata.
267. Which method is used to determine structural defects?
A. deterministic test pattern
B. algorithmic test pattern
C. random test pattern
D. exhaustive test pattern
Answer: A
Deterministic test patterns are used to detect specific faults or structural faults for a circuit under test.
268. 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
Answer: A
The deterministic test pattern method is also known as the stored test pattern method in the context of BIST applications.
269. Which method uses a finite state machine for developing the test pattern?
A. deterministic test pattern
B. algorithmic test pattern
C. random test pattern
D. exhaustive test pattern
Answer: B
The algorithmic test pattern method uses the hardware finite state machine for generating algorithmic test vectors for the circuit under test.
270. An n-bit counter produces ______ number of total input combinations.
A. 2(n-1)
B. 2(n+1)
C. 2n
D. 2n
Answer: C
An n-bit counter produces a total of 2n number of all possible input combinations for testing the circuit under test and it is called an exhaustive test pattern method.
271. Exhaustive test pattern determines
A. gate-level faults
B. logic level faults
C. functional faults
D. structural faults
Answer: A
The exhaustive test pattern method detects all gate level struck-at fault and also bridging fault.
272. An exhaustive test pattern also detects delay faults.
A. true
B. false
Answer: B
The exhaustive test pattern method does not detect all transistor-level faults or delay faults since those faults need specific ordering.
273. 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
Answer: A
The exhaustive test pattern method is not suitable for circuits having large N values since there is a limit for fault coverage.
274. 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
Answer: A
The exhaustive test pattern method needs fault simulation for determining fault coverage whereas the pseudo-exhaustive test pattern method does not need fault simulation.
275. 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
Answer: D
Pseudo-random test pattern method has properties similar to a random pattern sequence but the sequence is repeatable.
276. 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
Answer: C
The random test pattern method is used for external functional testing of microprocessors as well as in ATPG software.
277. Counters detect only bridging faults.
A. true
B. false
Answer: B
Counters detect gate-level struck-at faults and bridging faults of the circuit under test.
278. How many test patterns are required to test the circuit using counters?
A. 2n
B. 2(n-1)
C. 2n – 1
D. 2n + 1
Answer: A
An n-bit counter generates 2 n possible test patterns which are sufficient to completely test the n-bit combinational logic circuit with no feedback.
279. The desired N value for counters is
A. less than 50
B. less than 10
C. less than 25
D. less than 70
Answer: C
The testing using the counter method is practical for the lesser values of N such as within 22 to 25 since for higher values of N more number of clock cycles are necessary.
280. The least significant bit toggles for
A. every clock cycle
B. every alternate clock cycle
C. every two clock cycles
D. every four clock cycles
Answer: A
The least significant bit toggles every clock cycle and the most significant bit toggles every halfway through and at the end of the count sequence.
