Identify the gate from the truth table

Input		Output
A	B
0	0	1
0	1	0
1	0	0
1	1	1

XNOR Gate:

Symbol:

Truth Table:

Output Equation: \(Y={\overline{A\oplus B}}\)

Key Points: 

1) If B is always Low, the output is the inverted value of the other input A, i.e. A̅.

2) The output is low when both the inputs are different.

3) The output is high when both the inputs are the same.

4) XNOR gate produces an output only when the two inputs are the same.

XOR GATE

Symbol:

Truth Table:

Output Equation: \(Y = {\bf{A}} \oplus {\bf{B}} = \bar AB + A\bar B\)

Key Points: 

1) If B is always High, the output is the inverted value of the other input A, i.e. A̅.

1) The output is low when both the inputs are the same. 

2) The output is high when both the inputs are different.

NOT GATE

Symbol:

Truth Table:

Output Equation: Y = A̅

Key Points: The output of NOT gate is an invert of the input

AND GATE

Symbol:

Truth Table:

Output Equation: Y = A.B

Key Points: The output is high only when both the inputs are high

OR GATE

Symbol:

Truth Table:

Output Equation: Y = A + B

Key Points: The output is low only when both the inputs are low

NAND GATE

Symbol:

Truth Table:

Output Equation: \(Y = \overline {A.B} = \bar A + \bar B\)

Key Points:

1) The output is low only when both the inputs are high

2) It is a universal gate