Question

The Boolean expression for the given circuit is :

• A. $\overline{A}+\overline{B}$
• B. $\overline{A}+B$
• C. $A+\overline{B}$
• D. $\overline{A.B}$

Answer 1

Answer: (A)

$\overline{A}+\overline{B}$

The inputs are $A$ and $B$.

After going to $G_1$, $NAND$ gate, the output is $\overline{A.B}$

After going to $G_2$, $NOT$ gate, the output is $\overline{A}$

After going to $G_3$, $NOR$ gate, the output is $\overline{\overline{A}+B}$

After going to $G_4$, $OR$ gate, the output is $\overline{A}.B+\overline{\overline{A}+B}$

Now, the truth table of the output will be as follows-

$1,1,1,0$

This is the truth table of $\overline{A}+\overline{B}$