Logic Gates

LOGIC GATES

A logic gate is an elementary building block perform a basic logic function of a digital integrated circuit. Mostly logic gates take two binary inputs( 0 or 1 ) and give one output in 0 or 1. Boolean functions may be practically implemented by using electronic gates. 

Truth Table:

Truth table help us to understand the function of logic gate, it shows the behavior and inputs of logic gate relate to its output.

This is the way to understand how to make a truth table.

TYPES OF GATES:

There are seven types of logic gates which are listed below.

• AND
• OR
• NOR
• NAND
• XOR
• XNOR
• NOT

AND:

The AND gate is like a binary multiplication, if we say 0 is false and 1 is true then the gate acts as a logical AND operator.
AND gate is an electronic logical gates that give output high only when both k inputs are high. A dot(.) is used to show AND operator. (input 1 . input 2)

Here is a symbol and truth diagram of AND gate which helps us to understand easily.

Input 1	Input 2	Output
0	0	0
0	1	0
1	0	0
1	1	1

OR

OR gate is simply the addition of binary numbers (0 and 1) .

The OR gate is an electronic logical gate that gives a high output (1) if one or more of its inputs are high.  A plus (+) is used to show the OR operation. (input 1 + input 2)

Input 1	Input 2	Output
0	0	0
0	1	1
1	0	1
1	1	1

NOR

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.

Input 1	Input 2	Output
0	0	1
0	1	0
1	0	0
1	1	0

NAND

This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate.  The outputs of NAND gates are low if both the inputs are high.
NAND gate is known as universal gate; from this gate we can make other gates. 

The symbol is an NAND gate with a small circle on the output. The small circle represents inversion.

Input 1	Input 2	Output
0	0	1
0	1	1
1	0	1
1	1	0

XOR

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 EOR operation.

Input 1	Input 2	Output
0	0	0
0	1	1
1	0	1
1	1	0

XNOR

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

Input 1	Input 2	Output
0	0	1
0	1	0
1	0	0
1	1	1

NOT

Not gate is also known as invertor gate. It inverse the binary input as 0 is OFF then it give 1 as ON from output.

This is only a logical gate that have only one input.

Input	Output
1	0
0	1