Question

Draw the output Y in the given combination of gates.

• A.

  

• B.
• C.

  

• D.

  

Answer 1

The correct option is A

Step 1. Finding the output expression.

$y=A.\overline{B}$

Here, the first gate is a NAND gate and both inputs are the same. When the inputs are the same then it behaves like a NOT gate.

The second gate is OR gate and the third gate is NOT gate.

$\begin{array}{rcl}Y& =& \overline{\overline{A}+B}\\ & =& A·\overline{B}\end{array}$

$A=0\Rightarrow Y=0forB=0orB=1$

$A=1\Rightarrow Y=0forB=1$

$A=1\Rightarrow Y=1forB=0$

Hence, the output is $1$ only when input $A=1$ and $B=0$.

Step 2. Draw the output:

Therefore, the correct option is A.