What is Multiplexer and Demultiplexer?

Multiplexer and Demultiplexer
Multiplexer and Demultiplexer

Table of Contents

Multiplexer:

A multiplexer is a special type of combinational logic circuit that has many inputs, control signals, and a single output. A control signal controls which of the many inputs goes to the output. Multiplexer is abbreviated as MUX.

4×1 Multiplexer:

4×1 Multiplexer block diagram shows four inputs I0,I1,I2,I3 and one output y and two control signals S0 and S0. Which of the inputs I0,I1,I2,I3 will go as output y depends on the value of S0 and S1.

Multiplexer or 1x4 MUX block Diagram and Truth Table
Multiplexer or 1×4 MUX block Diagram and Truth Table

The truth table of a 4×1 Multiplexer with 4 input lines and one output line is shown. If we look at the truth table it will be seen that in this case S1=0 and S0=0 Output = I0 i.e. input I0 will go as output y. Again, if S0 = 0, S0=1 then output = I1, if S1 = 1, S0 = 0 then output = I2 and if S0= 1, S0 =1 then output = I3. The Boolean expression for the output y from the truth table is-

y= S1 S0I0 + S1 S0I1+S1 S0I2+ S1S0I3 [If S1 and S0 values are zero then the bar( ‾‾ ) will sit on its head]

Multiplexer or 1x4 MUX Logic Circuit
Multiplexer or 1×4 MUX Logic Circuit

Demultiplexer:

Demultiplexer is a special type of combinational logic circuit which has a single input, control and many outputs. This single input can be sent to any one of many lines and control which output line the control input goes to. Demultiplexer is the exact opposite of Multiplexer. Demultiplexer is abbreviated as De-MUX.

1×4 Demultiplexer:

A 1×4 Demultiplexer block diagram shows an Input (I) and outputs O0, O1, O2, and O3 and S0 and S1, as control lines. In this case, which of the Input (I) Outputs O0, O1, O2, and O3 depends on the control lines S0, and S1. On its quality. The truth table of a 1×4 Demultiplexer with one input line and 4 output lines is shown.

Demultiplexer or 1x4 MUX block Diagram and Truth Table
Demultiplexer or 1×4 MUX block Diagram and Truth Table

If we look at the truth table it can be seen that – if S1 = 0 and S0 = 0 then Input(I) goes to Output O0, if S1 =0 and S0 =1 then Input (I) goes to Output O1, when S1 = 1 and S0 = 0 then Input (I) goes to Output O2 goes, again S1 = 1and S0 = 1 then the Input (I) goes to the output O3. The Boolean expression of the outputs (O0, O1, O2 and O3) obtained from this truth table is-

O0 = S1 S0I,O1 = S1 S0I,O2 = S1 S0I,O3 = S1 S0I,

Demultiplexer or 1x4 MUX Logic Circuit
Demultiplexer or 1×4 MUX Logic Circuit

Frequently Asked Question (FAQs):

  • What is Multiplexer ?
  • 4×1 Multiplexer.
  • What is Demultiplexer?
  • 1×4 Demultiplexer.

Leave a Comment

Prepazu Logo

Prepare for any job exam by regularly attending PREPAZU quiz sessions. We provide competitive exam Q&A, QUIZ. Try it out now Online Quiz, Recruitment Notification, Scheme, Q&A & MCQ.

dmca