# Demultiplexer

A demultiplexer (or "demux" for short) is a digital circuit that selects one of several inputs and directs it to a single output. The selection of the input to be directed to the output is determined by the value of one or more "select" inputs. The demultiplexer has 2^n input lines and n select lines, where n is the number of select lines. The output will be the input line that corresponds to the binary value of the select lines.
It is the inverse operation of a multiplexer (mux).

## Demultiplexer applications

#### 1. Communication System

Multiplexers and Demultiplexers both are used in communication systems to carry out the process of data transmission. A De-multiplèxer receives the output signals from the multiplexer; and, at the receiver end, it converts them back to the original form.

#### 2. Arithmetic Logic Unit

The output of the arithmetic logic unit is fed as an input to the De-multiplexer, and the demultiplexer is connected to multiple registers. The output of the ALU can be stored in multiple registers.

#### 3. Serial to Parallel Converter

The serial to parallel the converter is used to reform parallel data. In this method, serial data are given as an input to the De-multiplexer at a regular interval and a counter is attached to the demultiplexer at the control i/p to sense the data signal at the demultiplexer's o/p When all data signals are stored, the output of the demultiplexer can be read out in parallel.

## Demultiplexer example

An example of a demultiplexer is a 2-to-1 demultiplexer which has two input lines (I0 and I1), one output line (O), and one select line (S). When the select line is at a logic 0, the input on I0 is directed to the output O, and when the select line is at a logic 1, the input on I1 is directed to the output O.

Here's a truth table of 2-to-1 demultiplexer:

SI0I1O
0000
0010
0101
0111
1000
1011
1100
1111

As you can see, when S = 0 , O = I0 and when S = 1 , O = I1

In general, demultiplexers can be implemented using multiplexers and logic gates.