# Logic gates – Logic diagram, Truth Table

## Logic gates

Logic gates are the key elements of any digital system. It is an electronic circuit with one or more inputs and one output only. The input output relationship is based on a certain logic. Logic gates are named AND gate, OR gate, NOT gate, etc. based on this.

## AND Gate

The figure shows a circuit that performs an AND operation. It has one output and n input (n > = 2).

Logic diagram

Truth Table

## OR Gate

The figure shows a circuit conducting an OR operation. It has n (n > = 2) input and one output.

Logic diagram

Truth Table

## NOT Gate

NOT gate,This is also known as Inverter. It has an input A and an output Y.

Logic diagram

Truth Table

## NAND Gate

A NOT-AND operation is referred to as the NAND operation. It has n input (n>=2) and one output.

Logic diagram

Truth Table

## NOR Gate

The operation of NOT-OR is known as an operation of NOR. It has one output and n input (n >= 2).

Logic diagram

Truth Table

## XOR Gate

XOR or Ex-OR gate is a particular gate type. In the half adder, full adder, and subtractor, it can be used. The exclusive-OR gate is abbreviated either as an EX-OR gate or as an X-OR gate sometime. It has n (n > = 2) input and one output.

Logic diagram

Truth Table

## XNOR Gate

XNOR gate is a particular type of gate. In the half adder, full adder and subtractor it can be used. The exclusive-NOR gate is abbreviated either as an EX-NOR gate or as a X-NOR gate sometimes. It has n (n > = 2) input and one output.

Logic diagram

Truth Table

The NAND and NOR gates are referred to as universal functions as the AND and OR functions can be generated with either and NOT.

Using NAND gates, a sum of products function can be implemented by replacing all AND and OR gates with NAND gates.

Using NOR gates, a function in the product of sums can be implemented by replacing all AND and OR gates with NOR gates.

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