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:
S | I0 | I1 | O |
---|---|---|---|
0 | 0 | 0 | 0 |
0 | 0 | 1 | 0 |
0 | 1 | 0 | 1 |
0 | 1 | 1 | 1 |
1 | 0 | 0 | 0 |
1 | 0 | 1 | 1 |
1 | 1 | 0 | 0 |
1 | 1 | 1 | 1 |
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.