The document presents a detailed overview of multiplexers and demultiplexers, including their definitions, types, applications, and the advantages and disadvantages associated with them. Multiplexers select data from multiple inputs and direct it to a single output, while demultiplexers reverse this process by taking a single input and distributing it to multiple outputs. Several types such as 4-to-1, 8-to-1, and 16-to-1 multiplexers along with their applications in communication systems, computer memory, and control systems are also discussed.

1. Presentation of
SUBMITTED BY SUBMITTED TO
NAME - SALEEM ANSARI Dr. SABBIR AHMAD SIR
CLASS - DEE - 3RD
SEMESTER
ROLL NO - 21DEE056
Topic - Multiplexers & Demultiplexers

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TABLE OF CONTENT
1.MULTIPLEXERS
1.1 Introduction
1.2 4 to 1 Multiplexer
1.3 8 to 1 Multiplexer
1.4 16 to 1 Multiplexers
1.5 Application of multiplexer
1.5.1- Communication System
1.5.2-Telephone network
1.5.3-Computer memory
1.5.4-Transmission from the computer system of a satellite
2. DEMULTIPLEXES
2.1 Introduction
2.2 What is Demultiplexer
2.3 1 to 2 Demultiplexer
2.4 1 to 4 Demultiplexer
2.5 2.5 Application of Demultiplexer
3. Advantages and disadvantages of Multiplexers and
Demultiplexers

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1-MULTIPLEXER (FROM R.K. GAUR)
1.1 -Introduction
A multiplexers is circuit which has a number of input but only 1 output or we
can say multiplexers is circuit which transmits a large number of information
signals(inputs) over a small number of signal lines(output) . Digital multiplexers
is a combinational logic circuit and its function is to select information in
binary from one of many inputs and outputs the information along a single
selected Output.
Let us have four input lines having signals as I0 , I1, I2and I3 . for selecting one of
the four input signals we requires address which can be 2 bit word. The address
lines are designated as S0 and S1 . for each combination of selection signals(S0 and
S1) one of the inputs is

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outputted .The truth table for having out as function of S0 and S1 .
S0 S1 I0 I1 I2 I3
0 0 1 0 0 0
0 1 0 1 0 0
1 0 0 0 1 0
1 1 0 0 0 1
Y = S0
’
S1
’
I0 + S0
’
S1I1 + S0 S1
’
I2 + S0 S1I3
4 to 1 Multiplexer

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1.3- 8 to 1 multiplexer (R.K GAUR BOOKS)
we can also designed an eight input multiplexers using three control signals the
truth table for such multiplexers is shown in below ..the bit selected for utput is
determined by appropriate input address line S0 S1 S2 out of the eight lines the
output enable is a high or 1. The circuit realisation of the above the truth table
FROM___(https://www.electronicshub.org/multiplexerandmultiplexing/)

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S0 S1 S2 I0 I1 I2 I3 I4 I5 I6 I7
0 0 0 1 0 0 0 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0
0 1 0 0 0 1 0 0 0 0 0
0 1 1 0 0 0 1 0 0 0 0
1 0 0 0 0 0 0 1 0 0 0
1 0 1 0 0 0 0 0 1 0 0
1 1 0 0 0 0 0 0 0 1 0
1 1 1 0 0 0 0 0 0 0 1
From the above truth table, the Boolean equation for the output is given as:
Y = S0’S1’S 2’D 0 + S0’S1’S2 D1 + S0’S1S2’D2 + S0’S1
S2D3 + S0S1’S2’D4 + S0 S1’S2 D5 + S0 S1 S2’D6 + S0
S1S2D7

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(8 TO 1 MUX DIAGRAM)

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1.4 - 16-to-1 Multiplexer
All the higher order Multiplexers like 8-to-1, 16-to-1, etc. can be implemented
using lower order multiplexers. But none-the-less, let us take a quick look at 16-to-
1 Multiplexer. 16-to-1 Multiplexer IC. The inputs to a 16-to-1 MUX are D0, D1,
D2 and so on up tp D15. Since it has 16 input lines, there will be 4 select lines
namely S0, S1, S2 and S3.
The following image shows the block diagram of a typical 16-to-1 Multiplexer.
FROM ---(https://www.electronicshub.org/multiplexerandmultiplexing/)
OR

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From ( https://www.electronicshub.org/multiplexerandmultiplexing/)
1.5- Applications of Multiplexer:-
Multiplexer are used in various fields where multiple data need to be transmitted
using a single line. Following are some of the applications of multiplexers –
1.5.1- Communication system – Communication system is a set of system that
enable communication like transmission system, relay and tributary station, and
communication network. The efficiency of communication system can be
increased considerably using multiplexer. Multiplexer allow the process of

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transmitting different type of data such as audio, video at the same time using a
single transmission line.
1.5.2. Telephone network – In telephone network, multiple audio signals are
integrated on a single line for transmission with the help of multiplexers. In this
way, multiple audio signals can be isolated and eventually, the desire audio signals
reach the intended recipients.
1.5.3. Computer memory - Multiplexers are used to implement huge amount of
memory into the computer, at the same time reduces the number of copper lines
required to connect the memory to other parts of the computer circuit. 4.
Transmission from the computer system of a satellite – Multiplexer can be used for
the transmission of data signals from the computer system of a satellite or
spacecraft to the ground system using the GPS (Global Positioning System)
satellites.
1.5.4. Transmission from the Computer System of a Satellite
The multiplexer is used to transmit the data signals from the computer system of a
spacecraft or a satellite to the ground system by using a GSM satellite
8-to-1 Mux Circuit
2- DEMULTIPLEXERS ( FROM R.K. GAUR BOOK)
2.1 Introduction
In the previous tutorial, we learned about Multiplexers or simply MUX.
Multiplexers are simple combinational logic circuit, which selects one of many
inputs and passes it through the single output. MUX is the device responsible for
Multiplexing.
The action or operation of a Demultiplexer is exactly the opposite to that of a
Multiplexer. As an inverse to the MUX, Demux has one input and many output .
From -- (https://www.electronicshub.org/multiplexerandmultiplexing/)

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2.2- What is a Demultiplexer?
The process of getting information from one input and transmitting the same over
one of many outputs is called Demultiplexing. Demultiplexing is just the opposite
of Multiplexing.
Input
A Demultiplexer is a combinational logic circuit that receives the information on a
single input line and transmits the same information over one of ‘n’ possible output
lines.
NOTE: The Demultiplexer ICs are also called as Decoder ICs. For example,
74159 is a 4-line to 16-line Decoder IC. (From -- (https://www.electronicshub.org/multiplexerandmultiplexing/)
2.3 - 1-to-2 Demultiplexer (R.K. GAUR
BOOK)
Example- A 1-to-4 demultiplexer requires 2 (22
= 4) select lines to control the 4
output lines.
A 1-to-2 demultiplexer consists of one input line, two output lines and one select
line. The signal on the select line helps to switch the input to one of the two
outputs. The figure below shows the block diagram of a 1-to-2 demultiplexer with
additional enable input.
In the figure, there are only two possible ways to connect the input to output lines,
thus only one select signal is enough to do the demultiplexing operation. When the
select input is LOW, then the input will be passed to Y0 and if the select input is
HIGH, then the input will be passed to Y1.
1: 2n
DE-MUX

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I
Truth Table.
S D X1 X0
0 0 0 0
0 1 0 1
1 0 0 0
1 1 1 0
(https://electricalfundablog.com/multiplexer-mux-types/)
2.4 - 1-to-4 Demultiplexer
1:2d emultiplexer

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A 1-4 Demux includes a single input like D, 2-selection lines like S1 & S0 & 4
outputs like X0, X1, X2 & X3. The data at input transmits to any one of the
outputs in a specified time for a specific arrangement of select lines. The 1:4
Demux block diagram and its truth table are shown below.
1 to 4 Demultiplexer Block Diagram-From the below truth table, we can
conclude that once both the select inputs are 0 & 1, the data input can be connected
to output X0. Similarly, once selection lines S0 & S1 are 0 & 1, then data input can
be connected to X1 output.
S1 S0 D X3 X2 X1 X0
0 0 0 0 0 0 0
0 0 1 0 0 0 1
0 1 0 0 0 0 0
0 1 1 0 0 1 0
1 0 0 0 0 0 0
1 0 1 0 1 0 0
1 1 0 0 0 0 0
1 1 1 1 0 0 0

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Likewise, the remaining outputs will be connected toward the input for the other
two select lines combinations. So, the Boolean expression for the outputs can be
derived by using the above truth table.
X0 = S0’ S1’ D
X1 = S1’ S0 D
X2 = S1 S0’ D
X3 = S1 S0 D
In the above expression, the input data is ‘D’, output lines are X0, X1, X2 & X3
and select lines are S0 & S1. By using the above Boolean expressions, the
implementation of a 1-4 Demux can be done with 4 AND gates & 2 NOT gates.
1 to 4 Demux Logic Diagram

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By using the above Boolean expressions, the implementation of a 1-4 Demux
can be done with 4 AND gates & 2 NOT gates. The two select lines like S0 & S1
will allow a specific AND logic gate at a time. In addition, there is a Strobe input
or an Enable pin which works as a universal enable input which means when the
enable bit is high then the outputs are active. So based on the combination of the
select inputs, input data can be transmitted using the selected gate toward the
associated output.
2.5 - Applications of DEMULTIPLEXERS
(https://www.electronicshub.org/multiplexerandm/ultiplexing)
The applications of Demultiplexer include the following.
1-Demultiplexers are used in control systems, microprocessors to enable or select
a single signal from a number of signals
2-Demux is used to choose several IO devices’ data routing.
Selecting different banks for memory decoding.
Implementation of a Boolean function
3-To enable various functional units
4. Used in synchronous systems for data transmission
5. Data acquisition systems
6. It enables several rows in memory chips based on the address
7. Designing of combinational circuits
8. Monitoring systems for security
9. Automatic test equipment systems
10. Demultiplexers are used within CLK data recovery solutions.
11. Applicable in wavelength routers.

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12. Used in the communication system for transmission of data
13. Used like a serial to parallel converter.
14. These are used in the broadcasting of ATM packets
15. The ALU output is stored within particular registers with the help of Demux
3 - Advantages and Disadvantages of Multiplexer
From --(https://www.electronicshub.org/multiplexerandmultiplexing/)
The advantages of multiplexer include the following.
In multiplexer, the usage of a number of wires can be decreased
It reduces the cost as well as the complexity of the circuit
2.The implementation of a number of combination circuits can be possible by
using a multiplexer
3. Mux doesn’t require K-maps & simplification
4. The multiplexer can make the transmission circuit less complex & economical
5. The dissipation of heat is less because of the analog switching current which
ranges from 10mA to 20mA.
6. The multiplexer ability can be extended to switch audio signals, video signals,
etc.
7. The digital system reliability can be improved using a MUX as it decreases the
number of exterior wired connections.
8. MUX is used to implement several combinational circuits
9. The logic design can be simplified through MUX.
 The disadvantages of multiplexer include the following.

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1. Additional delays required within switching ports & I/O signals which
propagate throughout the multiplexer.
2. The ports which can be utilized at the same time have limitations
3. Switching ports can be handled by adding the complexity of firmware
4. The controlling of multiplexer can be done by using additional I/O ports.
COMPARISON BETWEEN MULTIPLEXERS AND
DEMULTIPLEXERS
S.NO MUX DEMUX
1
2
3
4
A digital multiplexer is a combinational circuit
that chooses binary data from one of many input
lines and conducts it to a single output line.
Multiplexer contains multiple inputs and a single
output.
The multiplexer can increase the efficiency of the
communication system using transmission data
like transmission of audio and video.
The data conversion approach used in MUX is
parallel to serial and it is not complex to
understand because it uses multiple inputs.
A demultiplexer is a circuit that receives data on
a single line and transmits this data on one of
many output lines.
Demultiplexer contains single input and multiple
outputs.
Demultiplexer receives the o/p signals from the
Mux & changed them to the specific form at the
end of the receiver.
DEMUX works completely reverse to MUX
such as serial to parallel conversion. Therefore,
multiple outputs can be obtained in this case.

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