Code360 powered by Coding Ninjas X Naukri.com. Code360 powered by Coding Ninjas X Naukri.com
Last Updated: Mar 27, 2024
Difficulty: Easy
Leveraging ChatGPT - GenAI as a Microsoft Data Expert
Speaker
Prerita Agarwal
Data Specialist @
23 Jul, 2024 @ 01:30 PM

Introduction

XNOR gates are a basic part of digital electronics, kind of like building blocks for more complex stuff. Imagine them as simple switches that decide if a light should be on or off, based on certain rules. In this article, we're going to explore what XNOR gates are, how they look, and how they work. 

XNOR Gate

We'll start with the very basics, like their definition and symbols, and then move on to see them in action through examples and real-life uses. This way, you'll get a clear picture of their role and why they're important in electronics.

Definition

An XNOR gate is like a simple rule checker in the world of electronics. It's similar to agreeing with a friend on what to eat: if both of you want the same thing, it's a green light; if not, plans are off. In technical speak, when the two inputs to the XNOR gate are either both "on" or both "off," it happily outputs a "1," signaling agreement. But if one input says "yes" and the other "no," the gate outputs a "0," indicating disagreement. This straightforward principle is crucial for ensuring that electronic circuits perform their tasks correctly.

Get the tech career you deserve, faster!
Connect with our expert counsellors to understand how to hack your way to success
User rating 4.7/5
1:1 doubt support
95% placement record
Akash Pal
Senior Software Engineer
326% Hike After Job Bootcamp
Himanshu Gusain
Programmer Analyst
32 LPA After Job Bootcamp
After Job
Bootcamp

Symbol

Every electronic component has a special symbol, & the XNOR gate is no different. Picture this: a simple shape that stands for the gate's function in circuit diagrams. It looks like the standard symbol for an XOR gate but with an added circle at the output. It looks like this : ⊕. 

 XNOR gate

It tells us that the gate needs both inputs to be the same for a positive output. It's a way of keeping things clear & straightforward when building or understanding circuits, making sure everyone knows what part does what without any mix-ups.

Truth Table

Think of a truth table like a cheat sheet that shows how an XNOR gate decides its output. It's a simple chart with columns for every possible input combination and the resulting output. For an XNOR gate, the table has four main rows, representing all the ways you can flip two switches (inputs). When both switches are either ON or OFF together, the gate says, "Alright, that's a match," and gives a "1" as the output. But if one switch is ON and the other is OFF, it's a mismatch, and the gate responds with a "0." This table is super handy for quickly figuring out what an XNOR gate will do in any situation, making it easier to understand and predict the behavior of more complex circuits.

To illustrate the XNOR gate's operation more clearly, here's a simple truth table:

Input A Input B Output
0 0 1
0 1 0
1 0 0
1 1 1

In this table:

  • "0" represents OFF or false,
     
  • "1" represents ON or true.
     

The table shows that the XNOR gate's output is "1" (true) when both inputs are the same (both "0" or both "1") & "0" (false) when the inputs are different. It's a neat way to visualize the gate's rule: agreement leads to a positive output, disagreement leads to a negative one.

Boolean Expression

The Boolean expression for an XNOR gate might sound a bit like a math problem, but it's actually pretty straightforward. It's a way to write down the rule that the gate follows using letters and symbols. For an XNOR gate, this rule is like saying, "I'll give a positive output (1) if both my inputs are the same." In math language, this is written as A⊕B= A⊕B or A⋅B+ A . B

Here A and B are the inputs, ⊕ means 'OR', ⋅ means 'AND', and the line on top means 'NOT'. So, this expression is just a fancy way of saying, "Either both ON or both OFF equals a thumbs-up from me."

XNOR Gate Using Basic Logic Gates

Building an XNOR gate from simpler gates is like putting together a small puzzle. You start with basic pieces - the AND, OR, and NOT gates - & combine them in a specific way to get the XNOR function. Here’s a simple way to think about it:

AND Gate

It’s like a security check. Both inputs need to be "1" (or true) for the output to be "1".

OR Gate

This one is more lenient. If at least one input is "1", the output will be "1".

NOT Gate

Think of it as the opposite day. Whatever you input, you get the opposite output. If you put in "1", you get "0", and vice versa.

To create an XNOR gate, you take two inputs and send them through these gates in a special order. First, you make two paths:

  • Path 1: Put both inputs through an AND gate.
     
  • Path 2: Invert both inputs using NOT gates, then put them through another AND gate.
     

Then, you merge these paths using an OR gate. The result? An XNOR gate made from scratch. It will only give you a "1" when both inputs match, just like a standalone XNOR gate.

Implementation Using Transistor

Making an XNOR gate with transistors is a bit like building a small electronic puzzle. Transistors are tiny switches that can turn a signal on or off in electronic devices. To build an XNOR gate, we use a few transistors and connect them in a special way.

Here's a simple breakdown:

  • Transistors as Switches: Each transistor can be thought of as a tiny switch. When the right condition is met, the switch turns on, letting electricity flow through.
     
  • Combining Transistors: We arrange these transistor switches in a certain pattern. Some are connected to work together (like a team), and others are set up to do the opposite of what their teammates do.
     

By arranging these transistors, we create a path for electrical signals. When both input signals are the same (both on or both off), the transistors guide the electricity through the circuit in such a way that the output is turned on. But if the inputs are different, the circuit doesn't complete, and the output stays off.

This setup is a practical way to build an XNOR gate in real-life electronic devices, allowing them to make decisions based on the "agreement" between two signals.

Implementation using NAND Gate

Creating an XNOR gate with NAND gates is like using building blocks to make a new toy. A NAND gate is a basic element in electronics that says "no" only when all its inputs say "yes." It's a bit contrary but very useful.

To build an XNOR gate, you need to connect a few NAND gates together in a clever way:

  • Start with Inputs: Imagine you have two inputs, let's call them A and B.
     
  • Make Pairs: First, you connect A and B to a NAND gate. This is your starting pair.
     
  • Split & Combine: Then, you split each input into two paths. Each path goes through its own NAND gate. So, A goes to one NAND gate, and B goes to another. But, you also mix things up a bit by sending A and B together into a third NAND gate.
     
  • Final Touch: Now, you take the outputs from these three NAND gates and feed them into one last NAND gate. This final gate combines all the previous results.
     

By arranging these NAND gates in this specific order, you make a circuit that acts just like an XNOR gate. It gives a positive output when both inputs are the same and a negative output when they're different. It's a neat trick using just NAND gates!

Applications of XNOR Gates

XNOR gates, with their unique functionality, find their way into several crucial applications in the electronics and digital world. Here's a deeper look into where and how they're making a difference:

Error Detection and Correction

In digital communication systems, XNOR gates are key players in error checking mechanisms. They're used in parity generators and checkers, comparing sent and received data bits to detect and correct errors, ensuring data integrity during transmission.

Digital Logic Circuits

They serve as fundamental components in complex logic circuits, contributing to the decision-making processes within computers, smartphones, and other digital devices. By processing binary inputs, they help execute logical operations essential for computing tasks.

Memory Devices

XNOR gates are involved in the design of certain types of memory storage devices. They are used in flip-flops and latches, which are building blocks for memory elements in computers, allowing them to store and retain binary information.

Data Encryption

In cryptographic systems, XNOR gates can be used for data encryption and decryption processes. Their ability to compare inputs and produce a specific output makes them suitable for creating secure communication channels.

Arithmetic Operations

They are also utilized in performing arithmetic operations in digital calculators and computers. XNOR gates can be part of circuits designed for addition, subtraction, and other basic mathematical functions, aiding in accurate computations.

Pattern Recognition

In more advanced applications, like pattern recognition systems, XNOR gates help compare patterns or sequences of data. This is crucial in fields like biometrics and image processing, where matching patterns accurately is key.

Control Systems

In industrial and automation control systems, XNOR gates contribute to the logic behind sensors and actuators. They can help in decision-making processes that determine the actions of machinery based on specific conditions being met or not.

Digital Signal Processing

XNOR gates play a role in the processing and filtering of digital signals in electronics. They can be part of circuits that modify or analyze digital signals for various applications, from audio processing to digital communication.

Advantages

XNOR gates are quite the handy tools in electronics, offering some cool benefits:

Power Efficiency

They're good at saving energy. When used in circuits, XNOR gates can help reduce power usage, which is great for battery-powered devices like your smartphone or laptop.

Compact Design

Because of their specific function, XNOR gates can help make electronic circuits simpler and more compact. This means devices can do more without needing a lot of space, keeping things like your gadgets sleek and lightweight.

Reliability

XNOR gates are known for being reliable. They consistently perform their function, making them a dependable choice for important tasks in electronic circuits.

Versatility

They're quite versatile, working well with other logic gates to perform complex operations. This makes them a key player in various digital circuits, from simple gadgets to complex computer systems.

Error Detection

One of their standout roles is in error detection and correction systems. They can help spot mistakes in data transmission, ensuring the information you send or receive is accurate.

Signal Processing

In the realm of digital signal processing, XNOR gates are useful in filtering and manipulating data signals, contributing to clearer audio, video, and other digital content.

Cost-Effective

They can be a cost-effective solution in many digital circuits, contributing to lower production costs for electronic devices.

Disadvantages

Even though XNOR gates are super useful, they have a few downsides:

Complexity in Large Circuits

When you're building really big and complicated circuits, using lots of XNOR gates can make things tricky. It can get hard to keep track of everything and make sure it all works right.

Speed Limits

In some high-speed electronics, XNOR gates might not be the fastest option. This means they could slow down the operation a bit, especially when time is super important.

Limited Functions

XNOR gates have a specific job. Sometimes, you need other types of gates to do different tasks, so you can't use XNOR gates for everything.

Design Challenges

Putting together a circuit that uses a lot of XNOR gates can be a bit of a puzzle. It might take more time and effort to design and test to make sure it does what you want.

Power Consumption in Complex Uses

Even though they're generally power-efficient, in very complex or large-scale uses, they might use up more power, especially when compared to simpler gate configurations.

Solved Example

Let's walk through a simple example to see an XNOR gate in action:

Imagine you have an XNOR gate with two inputs, A and B. We'll look at what happens when we change these inputs.

Example 1

Input A is "1" (which means ON or true).

Input B is also "1".

Since both inputs are the same, the XNOR gate will give an output of "1". This is like saying, "Both inputs agree, so I'm giving a thumbs up!"

Example 2

Now, let's change it up. Input A is "1", but Input B is "0" (which means OFF or false).

This time, because the inputs are different, the XNOR gate's output will be "0". It's like the gate is saying, "The inputs don't match, so it's a no from me."

Example 3

What if both inputs are "0"?

Just like in the first example, because the inputs agree (both are "0" this time), the XNOR gate will output "1". Again, it's happy because the inputs are the same.

These examples show how the XNOR gate works like a little decision-maker, checking if its two inputs are the same or different and then giving its output based on that.

Frequently Asked Questions

Can XNOR gates be used in computers?

Yes, XNOR gates are used in computers. They help in checking data & making sure information is correct, which is key for a computer to work right.

Why are XNOR gates important in electronics?

XNOR gates are important because they help devices make decisions based on matching conditions. This is useful in many electronic systems for error checking and data processing.

How does an XNOR gate differ from an XOR gate?

An XNOR gate gives a positive output when its inputs match, either both "1" or both "0". An XOR gate is the opposite; it's positive only when the inputs are different.

Conclusion

XNOR gates, with their unique ability to check for matching input conditions, are crucial in the world of electronics. From ensuring data accuracy to simplifying complex circuits, their role is fundamental. Despite some limitations, like complexity in large systems or speed challenges, the versatility and efficiency of XNOR gates make them invaluable in various applications. Understanding these gates gives us a glimpse into the intricate workings of electronic devices, highlighting the importance of even the smallest components in achieving overall functionality and reliability.

You can refer to our guided paths on the Coding Ninjas. You can check our course to learn more about DSADBMSCompetitive ProgrammingPythonJavaJavaScript, etc. Also, check out some of the Guided Paths on topics such as Data Structure and AlgorithmsCompetitive ProgrammingOperating SystemsComputer Networks, DBMSSystem Design, etc., as well as some Contests, Test Series, and Interview Experiences curated by top Industry Experts.

Topics covered
1.
Introduction
2.
Definition
3.
Symbol
4.
Truth Table
5.
Boolean Expression
6.
XNOR Gate Using Basic Logic Gates
6.1.
AND Gate
6.2.
OR Gate
6.3.
NOT Gate
7.
Implementation Using Transistor
8.
Implementation using NAND Gate
9.
Applications of XNOR Gates
9.1.
Error Detection and Correction
9.2.
Digital Logic Circuits
9.3.
Memory Devices
9.4.
Data Encryption
9.5.
Arithmetic Operations
9.6.
Pattern Recognition
9.7.
Control Systems
9.8.
Digital Signal Processing
10.
Advantages
10.1.
Power Efficiency
10.2.
Compact Design
10.3.
Reliability
10.4.
Versatility
10.5.
Error Detection
10.6.
Signal Processing
10.7.
Cost-Effective
11.
Disadvantages
11.1.
Complexity in Large Circuits
11.2.
Speed Limits
11.3.
Limited Functions
11.4.
Design Challenges
11.5.
Power Consumption in Complex Uses
12.
Solved Example
12.1.
Example 1
12.2.
Example 2
12.3.
Example 3
13.
Frequently Asked Questions
13.1.
Can XNOR gates be used in computers?
13.2.
Why are XNOR gates important in electronics?
13.3.
How does an XNOR gate differ from an XOR gate?
14.
Conclusion