BEE BEE Bachelor of Electrical Engineering Digital Logic and Design Questions and Answers 2 — Questions and Answers
Question 1: What is the minimum number of two-input NAND gates required to implement an XOR function?
- 3
- 4 (Correct answer)
- 5
- 2
Correct answer: 4
An XOR gate can be constructed using exactly four two-input NAND gates.
Question 2: In a Karnaugh map for four variables, how many cells does each group of adjacent cells must contain?
- Any even number
- A power of 2 (Correct answer)
- A prime number
- A multiple of 3
Correct answer: A power of 2
Valid groupings in a K-map must contain 1, 2, 4, 8, or 16 cells, all powers of 2.
Question 3: Which flip-flop is known as a delay flip-flop because its output follows the input after one clock cycle?
- SR flip-flop
- JK flip-flop
- D flip-flop (Correct answer)
- T flip-flop
Correct answer: D flip-flop
The D flip-flop transfers its input to the output on the active clock edge, creating a one-cycle delay.
Question 4: What is the maximum number of states in a 4-bit Johnson counter?
- 4
- 8 (Correct answer)
- 16
- 32
Correct answer: 8
A 4-bit Johnson counter cycles through 2n = 8 unique states before repeating.
Question 5: In Boolean algebra, what does the consensus theorem state about the term AB + A'C + BC?
- It equals AB + A'C (Correct answer)
- It equals BC
- It equals AB + BC
- It equals A'C + BC
Correct answer: It equals AB + A'C
The consensus theorem states that BC is redundant when both AB and A'C are present, so AB + A'C + BC = AB + A'C.
Question 6: Which hazard in combinational circuits causes a momentary output of 1 when the expected output should remain 0?
- Static-1 hazard
- Static-0 hazard (Correct answer)
- Dynamic hazard
- Essential hazard
Correct answer: Static-0 hazard
A static-0 hazard produces a momentary glitch to 1 when the output should stay at a constant 0.
BEE BEE Bachelor of Electrical Engineering Digital Logic and Design Questions and Answers 2
What is the minimum number of two-input NAND gates required to implement an XOR function?