What is a Multiplexer?

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  • Originally Written By: Damir Wallener
  • Revised By: A. Joseph
  • Edited By: L. S. Wynn
  • Last Modified Date: 07 October 2015
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A multiplexer, sometimes referred to as a multiplexor or simply a mux, is an electronic device that selects from several input signals and transmits one or more output signals. In its simplest form, a multiplexer will have two signal inputs, one control input and one output. One example of an analog multiplexer is the source control on a home stereo unit that allows the user to choose between the audio from a compact disc (CD) player, digital versatile disc (DVD) player and cable television line, for example.

Multiplexers also are used in building digital semiconductors such as central processing units (CPUs) and graphics controllers. In these applications, the number of inputs is generally a multiple of two, the number of outputs is either one or relatively small multiple of two, and the number of control signals is related to the combined number of inputs and outputs. For example, a two-input, one-output multiplexer requires only one control signal to select the input, and a 16-input, four-output multiplexer requires four control signals to select the input and two to select the output.


Types of multiplexers also are used in communications. A telephone network is an example of a very large virtual multiplexer that is built from many smaller, discrete ones. Instead of having a direct connection from every telephone to every other telephone — which would be physically impossible — the network muxes individual telephone lines onto a small number of wires as calls are placed. At the receiving end, a demultiplexer, or demux, chooses the correct destination from the many possible destinations by applying the same principle in reverse.

There are more complex forms of multiplexers. Time-division multiplexers, for example, have the same input/output characteristics as other multiplexers, but instead of having control signals, they alternate between all possible inputs at precise time intervals. By taking turns in this manner, many inputs can share one output. This technique is commonly used on long-distance phone lines, allowing many individual phone calls to be spliced together without affecting the speed or quality of any individual call. Time-division multiplexers generally are built as semiconductor devices, or chips, but they also can be built as optical devices for fiber optic applications.

Even more complex are code-division multiplexers. Using mathematical techniques developed during World War II for cryptographic purposes, they have since found application in modern code division multiple access (CDMA) cellular networks. These semiconductor devices work by assigning each input a unique complex mathematical code. Each input applies its code to the signal that it receives, and all signals are simultaneously sent to the output. At the receiving end, a demux performs the inverse mathematical operation to extract the original signals.


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Post 60

How can I make a multiplexer 3x4 using a 4x4 multiplexer?

Post 59

What is the use of multiplexer in launch vehicle structure and also in vibro-acoustic structures?

Post 58

Please tell me how I can get an 8:1 multiplex using a 2:1 multiplex.

Post 55

Simple and good, but I need more details about TDM, FDM and CDM.

Post 54

How do you get a 2:1 Mux from a 8:1 Mux?

Post 51

How can I make a 16 bit multiplexer using an 8 bit multiplexer? Please tell me.

Post 50

How do i get a 16:1 multiplexer using two 4:1 multiplexers?

Post 49

How can i make a 64 bit multiplexer by using 16:1 multiplexer?

Post 48

what kind of multiplexer do i use with a satellite decoder that will show at least 10 channels in a room or flat? --Ebere.

Post 47

I get it. A multiplexer takes multiple "in" signals and creates a means for a single "out". A practical application (because I see questions for it) would be a TV. You have multiple sources, such as 'Line in','VGA','HDMI','Tuner','AVI','component1','component2', etc. These are the "in" channels. The controller is the board or chip in the TV in conjunction with the TV remote (controller). The "out" is your TV screen. Make sense?

Post 45

what are the real life applications of a multiplexer? --john

Post 43

how we can construct an 8-1 line mux with two 4-1 multiplexer? please help me.

Post 41

how does a 16:1,4:1,8:1 multiplexer work?

Post 40

i am not familiar with MUX.

Post 39

i know well about the definition of mux but i want to see its practical shape.

Post 38

how we make logic diagram 8:1 mux bu using and or gate?

Post 37

how can i made 16x1 multiplexer Block Diagram by using two 8x1 multiplexer.

Post 35

how to get a bcd to 7-segment decoder using a 4:1 mux?

Post 34

Please advise me how to make a device that connects with the camera 2cctv 1 vhs recorder. Thank you.

Post 32

how can i made 8x2 multiplexer using 4x1.

Post 31

who discovered the multiplexer?

Post 30

I want the clear definition for multiplexer -- and explain it.

Post 29

return for 16 to one using two 8 to 1, you use an and gate to choose which multiplexer(the forth control input besides the 3 control input in the 8 to 1 mux), then connect the two 8 to 1 multiplexer output to an or gate output.

Post 28

what is guard band and what is bandwidth?

Post 27

i need your help. just answer this question as soon as possible because i have an exam: what is the application of a multiplexer in combinational logic design?

Post 26

Please I need a help on this question!

Construct a quad 9-to-1-line multiplexer with four 8-to-1-line multiplexers and one quadruple 2-to-1-line multiplexer. The multiplexers should be interconnected and inputs labeled such so that the selection codes 0000 through 1000 can be directly applied to the multiplexer selection inputs without added logic. (Use block diagrams)

Help needed now, please!

Post 25

Can someone please help me out here :

How can i design a digital multiplexer by modifying a decoder? Thanks

Post 23

how do i construct a 16:1 line multiplexer?

Post 22

what is the application of a multiplexer?

Post 21

prove that multiplexer is a universally complete logic module.

Post 20

whatis purpose behind making a multiplexer?

Post 19

will you please tell me how to design and set up a 4:1 & 1:4 multiplexer?

Post 18

how to get 2:1 and 4:1 multiplexer?

Post 17

How do i get a 16:1 multiplexer using two 4:1 multiplexers?

Post 16

how do we know how much control signals are needed like in a 8x1 mux, we need 3 control signals? so how we will come to that we need 3 control signals?

Post 14

how to construct 16-to-1 multiplexer with two 8-t-o1 multiplexers and one 2-to-1 multiplexer

Post 13

What is the basic principle behind the multiplexer?

Post 12

I'm looking at this because I am going to set up data collection at my job and multiplexers from companies like Mitutoyo cost over a thousand dollars each. But this article makes it sound like a very simple device that should be relatively inexpensive. So could I purchase a "generic" multiplexer to receive the RS-232 outputs from devices instead of buying the proprietary ones with the company logos on them for a thousand bucks? I'd be a hero if I could do that.

Post 11


How is output made in a truth table multiplexer?

Post 10


my question is what is meant by mux k

now answer it

Post 9

A multiplexer is a device which takes one input line and gives two or more output lines.

On account of it, we don't need to take separate lines for separate devices, like a pc or analog phone. With one line we can connect our phone and pc for internet use. -sonu chaudhary

Post 7

how can i make a 3x16 bit multiplexer using 4x1 bit multiplexer?

Post 4

please define and explain encoder

Post 3


my question is, what is the purpose of a bus multiplexer?

can you reply to me as soon as possible..

thank you

Post 2

how to get 16:1 multiplexer using two 8:1 multiplexer

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