GATE CSE 2011 | Question: 13

Question

Which one of the following circuits is NOT equivalent to a $2$-input $XNOR$ (exclusive $NOR$) gate?

• A.
• B.
• C.
• D.

Answer 1

• A. $(AB'+A'B)'=A\odot B$
• B. $(A'(B')'+(A')'B')'=(A\oplus B)'=A\odot B$
• C. $A'B'+(A')'B=A\odot B$
• D. $((AB')'.(A+B'))'=(AB')+(A+B')'=AB'+A'B=A\oplus B$

So, Answer is (D)

Comments

$((A.B')'.(A+B'))' = A.B' + (A+B')' = A.B' + A'.B = A \oplus B$

I think this should be the expression.  Please re-check your option D)
@ srestha

Answer 2

All options except D produce XNOR. See following image (Source: http://clweb.csa.iisc.ernet.in/rahulsharma/gate2011key.html)

 

 

 

Source :GeeksforGeeks

Comments

Correction : All options except D produce XNOR.

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Corrected, thank you.