Hello Engineers. So, today I am going to talk about a basic foundational topic of digital electronics. Logic gates and types of logic gates with detailed explanation and their applications. So, let’s start with our today’s topic about the logic gates and types of logic gates with also practical circuits using transistors. Also, I have put a PDF download option below the post if you want to download a detailed PDF for this post.
What are Logic Gates?
A logic gate is a basic foundational/basic building block in the field of digital electronics. Logic gates usually take one or more inputs as binary form and produce only one output in the form of 0s or 1s. The inputs and the output depend on the type of gate. So let’s understand different types of gates.
Basic Logical gates
An AND gate is a type of logic gate that takes two or more inputs and produces only one output after performing the AND operation. Below are the symbol and the truth table.
Logical AND expression is as follows:-
Y = A AND B
Y = A * B
Y = AB
|INPUT A||INPUT B||OUTPUT Y (A AND B)|
A NOT gate, also called an inverter takes 1 input and produces complement of it as output. A NOT expression is as follows:- Y = NOT A => Y = A’ (compliment of A).
TRUTH TABLE NOT GATE
|INPUT A||OUTPUT A’ OR A COMPLIMENT|
An OR Gate takes 2 or more inputs and performs logical OR operation to produce a single output.
Y = A OR B => Y= A+B
This is a gate whose output is low when inputs are the same and high when both the inputs differ.
XOR gate symbol and expression:-
|INPUT A||INPUT B||OUTPUT|
It is a gate that provides a high output on the same inputs.
|INPUT A||INPUT B||Y ( A XNOR B )|
A NOR gate is a universal gate that is made up of an OR gate followed by a NOT gate. The input is first OR and then OR gate output undergoes NOT operation.
NOR Gate symbol and expression:-
TRUTH TABLE OF NOR GATE
|INPUT A||INPUT B||OUTPUT (A+B)’|
7. NAND Gate:-
A NAND Gate is a Universal gate made by using an AND Gate followed by a NOT gate. Below is the symbol and the logical expression for a NAND gate followed by a truth table.
|INPUT A||INPUT B||OUTPUT Y(A*B)’|
Applications of Logical Gates
Logic Gates are basically used in devices where we need to perform some computation, programming or processing of some input. Input is in form of binary digits i.e, 0 and 1. There are also some other applications of logic gates. Below are listed some of the applications of logic gates.
- NAND Gate( AND & NOT) is used in inverters, Motor control systems.
- Flip-flops, counters, Memory devices.
- Alarms clocks.
- Computational and processing devices like Desktop, Laptop, Mobile phones, calculators.
- Data storage devices, CPU- Registers, RAM, ROM.
- Devices like multiplexers, Demultiplexers, Encoders, Decoders.
- Micro-controllers and micro-processors.
- Almost every electronics device in today’s world is making use of logical circuits.
- Electronics Debugging tools and instrumentations.
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