A logic gate is an digital circuit which follows logical relationship between input and output voltages
It has one output and one or more inputs
They are the basic building blocks from which most of the digital systems are build up
They are called logic gates as they control the flow of information
The five common logic gates used are NOT, AND, OR, NAND, NOR.
Each logic gate is indicated by a symbol and its function is defined by a truth table that shows all the possible input logic level
combinations with their respective output logic levels.
Truth tables help understand the behaviour of logic gates.
AND gate
This gates has two or more input and one output. The output Y of AND gate is 1 only when both the input A and B are 1.
Here is the logical symbol of AND gate
Truth Table is given below as
NOT gate
This gates has one input and one output. This is most simplest gate. It produces a '1' output if the input is '0' and vice-versa.
It is also called inverter
Here is the logical symbol of NOT gate
Truth Table is given below as
OR gate
This gates has two or more input and one output. The output Y of OR gate is 1 when either input A or input B or both are 1s
Here is the logical symbol of OR gate
Truth Table is given below as
NAND gate
This is AND gate followed by NOT gate. If inputs A and B are both '1', the output Y is not '1'.
The gate gets its name from this NOT AND behaviour
This is also called universal gate as all other gates can be created from it
Truth Table is given below as
NOR gate
This is OR gate followed by NOT gate. Its output Y is '1' only when both inputs A and B are '0'
The gate gets its name from this NOT OR behaviour
This is also called universal gate as all other gates can be created from it
