Construct 4 to 1 Multiplexer Using Logic Gates

Share

A multiplexer is a Combinational circuit (it is a type of circuit whose output rely on the given inputs using various logic gates ) that takes multiple inputs and delivers only a single output. It consists input data lines, selection lines and a single output.

To construct a 4 to 1 multiplexer, we need to know how many selection lines we required to create a MUX?

We require  n selection lines, where 2n represents total input lines and  n represents selection lines. (In this case, 22 that gives 4 input lines and 2 selection lines).

A multiplexer is often abbreviated as MUX or many to one circuit or parallel to serial circuit.

It is a data selector that provides the mechanism to select single binary information from many input lines and passes it to output line

Advantages of Multiplexer:

  • It is less costly and reduces transmission circuit complexity
  • It can be used to implement many combinational circuits
  • It reduces number of wires

Applications of Multiplexer:

  • It is used in communication system i.e Satellite systems, telephone networks
  • It is used to read data from memory locations in computer memory

Types of Multiplexer
There are various types of multiplexers and few are given below:

  • 2:1 MUX
  • 4:1 MUX
  • 8:1 MUX
  • 16:1 MUX
  • 32:1 MUX

In this article, we’ll be discussion 4:1 MUX.

Here are the steps to design or construct 4 to 1 Multiplexer or 4:1 MUX using Logic Gates :

1) Now, make a diagram of multiplexer with 4 input lines, 2 selection lines and 1 output. In below diagram, A0 , A1 , A2 and A3 are input data lines, S0 and S1 are Selection lines and lastly one output line named Y.

 

2) This is how a truth table for 4 to 1 MUX looks like . According to the truth table, the output of the multiplexer fully depends on selection lines (binary data , 00,01,10 & 11) and one input would be selected from all the input data lines as the output.


Truth table

 Selection Lines   Output
S0S1Output
00A0
01A1
10A2
11A3

Above  table is created as per follow :

When S0 =0 and S1=0 , then A0 would be the output.
Similarly When S0 =0 and S1=1 , then A1 would be the output.

We can represent this by an expression.
Output = S0‘.S1‘A+ S0‘.S1A1+ S0.S1‘A2 + S0.S1 A3

3) In last step, design 4 to 1 multiplexer by using 4 AND gates and a single OR gate.

Explanation:

In above diagram, there were two selection lines along with their respective complements using Inverters. Each and every AND gate were holding three inputs from S1, S0 and a particular input A. lastly, outputs of all AND gates became the input for OR gate and providing a single output.

This post was last modified on July 4, 2022

Sandeep Verma

Published by
Sandeep Verma
Tags: 4 to 1 multiplexer Computer organisation de Digital Electronic logic gates Multiplexer