NOT GATE
Symbol:
Truth Table:
Input (A) |
Output (A̅) |
0 (Low) |
1 (High) |
1 (High) |
0 (low) |
Output Equation: Y = A̅
Key Points: The output of NOT gate is an invert of the input
AND GATE
Symbol:
Truth Table:
Input A |
Input B |
Output Y = A.B |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
1 |
Output Equation: Y = A.B
Key Points: The output is high only when both the inputs are high
OR GATE
Symbol:
Truth Table:
Input A |
Input B |
Output Y = A + B |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
1 |
Output Equation: Y = A + B
Key Points: The output is low only when both the inputs are low
NAND GATE
Symbol:
Truth Table:
Input A |
Input B |
Output \(Y = \overline {AB}\) |
0 |
0 |
1 |
0 |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
0 |
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
NOR GATE
Symbol:
Truth Table:
Input A |
Input B |
Output \(Y = \overline {\left( {A + B} \right)}\) |
0 |
0 |
1 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
Output Equation: \(Y = \overline {A + B} = \bar A.\bar B\)
Key Points:
1) The output is high only when both the inputs are low
2) It is a universal gate
XOR GATE
Symbol:
Truth Table:
Input A |
Input B |
Output Y = A ⊕ B |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
0 |
Output Equation: \(Y = {\bf{A}} \oplus {\bf{B}} = \bar AB + A\bar B\)
Key Points:
1) The output is low when both the inputs are the same
2) The output is high when both the inputs are different
XNOR GATE
Symbol:
Truth Table:
Input A |
Input B |
Output Y = AB |
0 |
0 |
1 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
1 |
Output Equation: \(Y = \overline {{\bf{A}} \oplus {\bf{B}}} = A \odot B = AB + \bar A\bar B\)
Key Points:
1) The output is high when both the inputs are the same
2) The output is low when both the inputs are different
∴ The correct answer is option 1.