Demultiplexer in Digital Electronics

In this lecture, we are going to cover another combinational circuit called Demultiplexer in Digital Electronics. We will cover what a is Demultiplexer, the block diagram of the Demultiplexer, the types of Demultiplexer, the need for Demultiplexer, and the advantages of Demultiplexer and in the end, we will see the application of Demultiplexer.

Also Read: Multiplexer in Digital Electronics

What is Demultiplexer

The block diagram of Demultiplexer is shown in the below figure. It has only one input, n0outputs, and m-select inputs.

A demultiplexer performs the reverse operation of a multiplexer i.e. it receives one input and distributes it over several outputs.

At a time only one output line is selected by the select lines and the input is transmitted to the selected output line.

Hence a demultiplexer is equivalent to a single pole multiple-way switch.

The enabled input will enable the demultiplexer. The relation between the n output lines and m select lines is as follows:

n = 2^m

Types Of Demultiplexer

Sure! Here is a table showcasing the different types of demultiplexers:

Types Of Demultiplexer	Input Lines	Output Lines	Select Inputs
1 to 2 Demultiplexer	1	2	1
1 to 4 Demultiplexer	1	4	2
1 to 8 Demultiplexer	1	8	3
1 to 16 Demultiplexer	1	16	4
1 to n Demultiplexer	1	n	m

Each demultiplexer type allows you to select one of the output lines based on the combination of input values for the given number of input lines and select inputs.

So, now we are going to learn about each type of demultiplexer in detail.

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1 To 2 Demultiplexer

• The block diagram of 1 to 2 demultiplexer is shown in the figure below. It has one data input D_in, one select input S₀, one enable (E) input, and two outputs Y₀ and Y₁.

1 to 2 Demultiplexer Truth Table

• The 1 to 2 demultiplexer truth table is shown in the below figure.

• If E = 0 then both the outputs will be 0 irrespective of the inputs.

Realization of 1 to 2 Demultiplexer

• Step 1: To realize the 1 to 2 demultiplexer using the gates, we have to write the truth table as given in the below image.

• Step 2: Write the K-map.

Thus the expressions for Y0 and Y1 are as follows:

\mathbf{Y_0 = ED_{in}\bar S_0} and \mathbf{Y_1 = ED_{in} S_0}

1 to 2 Demultiplexer Circuit Diagram

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1 To 4 Demultiplexer

• The block diagram of 1 to 4 demultiplexer is shown in the figure below.

• D_in is connected to Y₀ when S₁S₀ = 00, it is connected to Y₁ when S₁S₀ = 01, and so on. The other outputs will remain zero.

• The enable inputs need to be high in order to enable the demux. If E = 0 then all the outputs will be low irrespective of everything.

1 to 4 Demultiplexer Truth Table

• The 1 to 4 demultiplexer truth table is shown in the below figure.

1 to 4 Demultiplexer K-map

• The K-maps for the four outputs are shown in the figure below.

1 to 4 Demultiplexer Circuit Diagram

• The 1 to 4 Demultiplexer Circuit Diagram is shown in the below figure.

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1 to 8 Demultiplexer

• The block diagram of 1 to 8 demultiplexer is shown in the figure below.

• It has one data input, eight outputs, three select inputs, and an enable input E.

• Depending on the combination of the select inputs S₂ S₁ S₀, the data input D_in is connected to one of the eight outputs.

• For example if S₂ S₁ S₀ = 1 1 0 then D_in is connected to Y₆.

1 to 8 Demultiplexer Truth Table

• The 1 to 8 Demultiplexer Truth Table is shown in the below figure.

1 to 8 Demultiplexer Circuit Diagram

• The 1 to 8 Demultiplexer Circuit Diagram is shown in the below figure.

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Application of Demultiplexer

Demultiplexers, often abbreviated as “demux,” have various practical applications in electronics and digital systems. Their primary function is to take a single input signal and distribute it to one of several output lines based on a control signal. Here are some common application of demultiplexer:

1. Data routing within digital systems
2. Display multiplexing in LED or LCD displays
3. Address decoding in microprocessor systems
4. Selecting analog input channels in analog-to-digital converters (ADCs)
5. Separating channels in communication systems
6. LED matrix scanning for displays
7. Controlling print head elements in printers
8. Routing signals in programmable logic devices (PLDs) and FPGAs
9. Instrumentation and test equipment for signal distribution
10. Channel selection in digital signal processing (DSP) applications

FAQs on Demultiplexer

Also Read

• Half Adder in Digital Electronics
• Full Adder in Digital Electronics
• Half Subtractor in Digital Electronics
• Full Subtractor in Digital Electronics