Introduction to Logic Gates and Boolean Expressions
We are living in an electronic era.
Where electronic devices/machines can do the work with more efficiency and more easily than a human being.
And that electronic devices are as calculators, smartphones, etc.
Each and every electronic device are having several types of electronic circuits.
When an engineer designs a circuit, they need to explain the behavior of the circuit.
For example, if we design a circuit to calculate the addition of two values.
Now, when we give the input as
$4$
and
$5$
then we expect to get the number
$9$
.
After that, when we give the input as
$3$
and
$4$
then we expect to get the number
$7$
.
So, this is the behavior of a circuit and it can be only described by using logic gates.
The logic gates are only worked on the boolean values.
Let's discuss the logic gates and boolean expressions.
Boolean algebra is the special kind of algebra which is based on some logical statement and consist of two variables.
Hence, the boolean algebra is of two types. It can be high and low or ON and OFF or true and false, etc.
The variables used in boolean algebra are binary and it's represented by
$0$
and
$1$
.
The boolean expressions are a combination of two or more boolean variables with some logical statements.
And the output we get in another boolean variable.
Now, the logic gates are the digital circuits which work under the logical expressions with the help of boolean algebra.
There are three basic types of logic gates.
OR gate is a logic gate that produces inclusive disjunction. Its function is to find the maximum between the inputs.
This is the symbol of the OR gate.
$A$
and
$B$
are the inputs and we get the output as
$Y$
.
Now, the boolean expression of this OR gate is written as,
The representation of the behavior of logic gates by a table is called a truth table.
So, the truth table of this OR gate is as,
Now, AND gate is an electronic circuit which gives the high input only if all inputs are high.
This is the symbol of the AND gate.
Now, the boolean expression of this AND gate will be as,
The truth table of this AND gate is as,
Now, NOT gate is complementary of input variables.
This is the symbol of NOT gate.
So, its boolean expression is as,
This is the truth table of the NOT gate.
This is all about the three basic types of the logic gate.
Revision
There are three basic types of logic gates.
OR gate is represented as,
AND gate is represented as,
NOT gate is represented as,
The End