Introduction to Multiplexer(MUX)


1. It is a combinational circuit. 

The basic design unit of MUX is  : 2^{n} \rightarrow 1


  It means in a 2^{n} \rightarrow 1  MUX, there are

  •  2^{n} input lines
  • n select lines      // Select lines are used to select the inputs.
  • 1 output

2. A multiplexor is a  functionally complete combinational circuit. for example, a 4*1 MUX can represent any Boolean function of two variable.

3. To implement an n variable boolean function you need  2^{n}\rightarrow 1 MUX, in normal case.


Implementing 4*1 MUX



                       {\color{Red} f= S_{1}'S_{0}'I_{0} +S_{1}'S_{0}I_{1} +S_{1}S_{1}'I_{2}+ S_{1}S_{0}I_{3}}


Sometimes you need 2^{n-1}\rightarrow 1  to implement an n variable boolean function, but you need some additional circuit to implement this.




A multiplexer is a combinational circuit that selects one of several input signals and forwards the selected input into a single output line.
A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output.
The block diagram of a 4x1 multiplexer is as below: