Introduction of Logic Gates

1. AND Gate

    Logic Diagram :

AND Gate

• The AND gate is an electronic circuit that gives a high output (1) only if all its inputs are high. 
• A dot (.) is used to show the AND operation.

     AND Gate Truth Table : 

Inputs		Output
A	B
0	0	0
0	1	0
1	0	0
1	1	1

2. OR Gate

    Logic Diagram :

OR Gate

• The OR gate is an electronic circuit that gives a high output (1) if one or more of its inputs are high. 
• A plus (+) is used to show the OR operation.

    OR Gate Truth Table : 

Inputs		Output
A	B
0	0	0
0	1	1
1	0	1
1	1	1

3. NOT Gate

    Logic Diagram :

NOT Gate

• The NOT gate is an electronic circuit that produces an inverted version of the input at its output.  
•  It is also known as an inverter gate.

    NOT Gate Truth Table :

Inputs	Output
A
0	1
1	0

4. NAND Gate

    Logic Diagram :

NAND Gate

• This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate. 
• The outputs of all NAND gates are high if any of the inputs are low. 
• The symbol is an AND gate with a small circle on the output. 
• The small circle represents inversion.

     NAND Gate Truth Table : 

Inputs		Output
A	B
0	0	1
0	1	1
1	0	1
1	1	0

5. NOR Gate

    Logic Diagram :

NOR Gate

• This is a NOT-OR gate which is equal to an OR gate followed by a NOT gate.  
• The outputs of all NOR gates are low if any of the inputs are high.
• The symbol is an OR gate with a small circle on the output.  
• The small circle represents inversion.

    NOR Gate Truth Table : 

Inputs		Output
A	B
0	0	1
0	1	0
1	0	0
1	1	0

6. EXCLUSIVE-OR Gate

    Logic Diagram :

Exclusive-OR Gate

• The 'Exclusive-OR' gate is a circuit which will give a high output if either, but not both, of its two inputs are high. 
• An encircled plus sign () is used to show the Exclusive-OR operation.

   Exclusive-OR Gate Truth Table : 

Inputs		Output
A	B
0	0	0
0	1	1
1	0	1
1	1	0

7. EXCLUSIVE-NOR Gate

    Logic Diagram :

Exclusive-NOR Gate

• The 'Exclusive-NOR' gate circuit does the opposite to the Exclusive-OR gate. 
• It will give a low output if either, but not both, of its two inputs are high.
• The symbol is an Exclusive-OR gate with a small circle on the output. 
• The small circle represents inversion.

   Exclusive-NOR Gate Truth Table : 

Inputs		Output
A	B
0	0	1
0	1	0
1	0	0
1	1	1