GATE 2014 EC (EC4) – Question 25

Digital Circuits · Combinatorial Circuits · 1 mark · Multiple choice

For C = 0 in the circuit shown, find Y.

Diagram for GATE 2014 EC (EC4) question 25

$A\overline B+\overline AB$
$A+B$
$\overline A+\overline B$
$AB$

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Correct answer: (A) $A\overline B+\overline AB$

Explanation

With C=0the inverted C input to the final NAND is1. Its other input becomes(A+B)̄+AB=ĀB̄+AB, the XNOR function. The final NAND complements it, giving **Y=AB̄+ĀB,A**, an XOR.