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# What is Demultiplexer in Digital Circuit?

Last Updated on March 13, 2023 by Prepbytes

A demultiplexer is a digital circuit that takes a single input signal and chooses one of several output lines based on a set of control signals (also known as a demux or data selector). It essentially serves the opposite purpose from a multiplexer, which selects one output from a multiple of inputs.

## What is Demultiplexer?

The typical component of a demultiplexer is a binary decoder, which uses the control signals to decide which output line to activate. A 1-to-4 demultiplexer, as an illustration, has one input line and four output lines. Data from the input lines are forwarded to the chosen output line after one of the four output lines has been chosen using the control signals.

Demultiplexers are used in a variety of digital applications, including memory address decoding, communication systems, and digital signal processing. They can also be used to distribute a single input signal to numerous outputs or to connect multiple devices to a single output line.

In the above demultiplexer, one input A is given and one select S is also given. 1 x 2 demultiplexer give two output y1 and y2. Let’s see the truth table for 1 x 2 demultiplexer.

Truth Table:

### 1 x 4 Demultiplexer:

There are a total of four outputs in the 1 x 4 De-multiplexer, namely Y0, Y1, Y2, and Y3, two selection lines, namely S0 and S1, and a single input, namely A. A connection between an input and an output is made based on the combination of inputs that are present at the selection lines S0 and S1. Following are the 1 x 4 demultiplexer’s block diagram and truth table.

Truth Table of 1 x 4 Demultiplexer:
The truth table of 1 x 4 demultiplexer is given below.

Logic Circuit of 1 x 4 Demultiplexer:
The logical circuit of 1 x 4 demultiplexer is given below.

### 1 x 8 Demultiplexer:

Eight outputs, or Y0 through Y7, three selection lines, or S0 through S1, and a single input, or A, make up the 1 to 8 De-multiplexer. The input will be connected to one of these outputs based on the combination of inputs that are present at the selection lines S0, S1, and S2. The 18 de-block multiplexer’s diagram and truth table are provided below.

Truth Table of 1 x 8 Demultiplexer:
The truth table of 1 x 8 demultiplexer is given below.

How to build 1 x 8 Demultiplexer using 1 x 4 and 1 x 2 Demultiplexer?
With the help of two 1 x 4 demultiplexers and one 1 x 2 demultiplexer, we can build higher-order 1 x 8 demultiplexers. Two selection lines S0 and S1 are connected with two 1 x 4 demultiplexers while one selection line is connected with one 1 x 2 demultiplexer.

We require two 1 x 4 demultiplexers to obtain 8 data outputs. Two outputs are produced by the 1 x 2 demultiplexer. Therefore, the outputs of the 1 x 2 demultiplexer must be input to the 1 x 4 demultiplexer in order to obtain the final output. Below is a block diagram of a 1 x 8 demultiplexer using a 1 x 4 and 1 x 2 demultiplexer.

Conclusion
In conclusion, this article will help you to understand what is demultiplexer and the various types of the demultiplexer with its truth table and logical circuit of the particular demultiplexer.

1. What is the purpose of a demultiplexer?
The purpose of a demultiplexer is to enable a single input signal to be distributed to multiple output lines, based on the value of the control signals. This can be useful in various digital applications, such as data transmission and signal processing.

2. What is the difference between a demultiplexer and a decoder?
A demultiplexer takes a single input and distributes it to one of several outputs, while a decoder takes a binary input and generates an output code. Demultiplexers and decoders can be used together to implement complex digital circuits.

3. What is the difference between a demultiplexer and a multiplexer?
A demultiplexer takes a single input and distributes it to one of several outputs, while a multiplexer takes multiple inputs and selects one of them to output. Demultiplexers and multiplexers are complementary circuits and can be used together to implement complex digital systems.

4. What is the maximum number of output lines that a demultiplexer can have?
The maximum number of output lines that a demultiplexer can have depends on the specific implementation and the capabilities of the digital circuit design tools. However, demultiplexers with up to 16 output lines are commonly used in digital circuits.

5. What is the difference between a passive and an active demultiplexer?
A passive demultiplexer uses passive components, such as resistors and capacitors, to distribute the input signal to the output lines. An active demultiplexer uses active components, such as transistors and logic gates, to perform the demultiplexing function. Active demultiplexers are more common in digital circuit design, as they are typically faster and more efficient than passive demultiplexers.

6. What is a "de-muxing circuit"?
A de-muxing circuit is a circuit that uses one or more demultiplexers to distribute a single input signal to multiple output lines. De-muxing circuits can be used in various digital applications, such as signal processing and memory addressing.