Multiplexer - MUX For ISC Students

A Multiplexer (MUX) can be described as a combinational logic circuit used to select only one input among several inputs based on selection lines

This can act as a digital switch

This is also called as data selector

In a MUX, there can be 2^n inputs, n selection lines and 1 output

‘n’ must be atleast 1

 

Diagram of a 2^n MUX 

When we are designing the truth table of a MUX, we have to consider only the selection lines, not inputs as out is dependent on selection lines and not on inputs.

 

Design of a 2 X 1 MUX

 2 X 1 MUX means 2 inputs and 1 output

2 ^ n=1

2^1=1^1

So n=1

 

Truth Table of 2X1 MUX

Selection line may have either 0 or 1. If it is 0, output will be input at 0 port, means D0 and D1 for selection line 1.

So, Y=D0S’ + D1S

 

Logic Circuit

In all MUX logic circuit, there will be an OR gate at the end.

 

 4 X 1 MUX

2^n=4

2^2=2^2

N=2

So, 2 selection lines and 4 inputs

Truth Table of 4 X 1 MUX

Boolean expression of this truth table is as follows:

Y=D0S0’S1’ + D1S0’S1 + D2S0S1’ + D3S0S1

 

Logic Circuit