Question

The logic performed by the circuit shown in the figure is equivalent to:

• A. AND gate
• B. OR gate
• C. NOR gate
• D. NAND gate

Answer 1

The Correct Option is A

The given circuit consists of two NOT gates followed by an OR gate with a NOT gate at the output. Let's analyze the circuit step-by-step:

1. The inputs to the circuit are A and B.
2. Both inputs A and B pass through NOT gates first. This inverts the inputs:
   • If A = 0, then NOT A = 1.
   • If A = 1, then NOT A = 0.
   • If B = 0, then NOT B = 1.
   • If B = 1, then NOT B = 0.
3. The outputs of the NOT gates, i.e., NOT A and NOT B, are then fed into an OR gate. The OR gate performs the operation:
   • OR Gate Output = (NOT A) + (NOT B)
   • Using logical OR: (NOT A) + (NOT B) = 1 if either NOT A = 1 or NOT B = 1
4. The output of the OR gate is then inverted by the final NOT gate:
   • The final output Y is the inverse of the OR gate output: Y = NOT((NOT A) + (NOT B))
5. This final expression Y is equivalent to the AND operation by De Morgan's theorem:
   • Y = A AND B (as NOT((NOT A) + (NOT B)) = A AND B)

Therefore, the logic performed by the given circuit is equivalent to an AND gate, as confirmed by the analysis above.