JEE Main · 2025 · 28 Jan 2025 · Shift 1 · Semiconductors

Which of the following circuits has the same output as that of the given circuit?

Answer: (A)

Solution

Let the inverter act on B to give

\overset{ˉ}{B}

. The upper AND gate produces

P = A \cdot \overset{ˉ}{B}

; the lower AND gate produces

Q = A \cdot B

. These feed a NOR gate, whose output is

Y = \overline{P + Q} = \overline{A \overset{ˉ}{B} + A B} = \overline{A (\overset{ˉ}{B} + B)} = \overline{A \cdot 1} = \overset{ˉ}{A}

The output depends only on A and equals its complement, so the circuit with matching output is a single NOT gate with A as its input.

JEE Main · 2025 · 28 Jan 2025 · Shift 1 · Single correct option