Multiple choice

The digital logic shown in the figure satisfies the given state diagram when Q1 is connected to input A of the XOR gate.

Suppose the XOR gate is replaced by an XNOR gate. Which one of the following options preserves the state diagram?

  1. Input A is connected to $\overline{Q_2}$
  2. Input A is connected to $\overline{Q_2}$
  3. Input A is connected to $\overline{Q_1}$ and S is complemented
  4. Input A is connected to $\overline{Q_1}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\text{When $Q_1$, is connectede to input A, then we have the input $D_2$ as} \\ D_2 = A \oplus S \\ \hspace{0.6cm} = Q-1 \oplus S = Q_1 \bar{S} + \bar{Q_1}S$