Multiplexer and Demultiplexer


The Term ‘multiplex‘ means “many into one“. Multiplexing is the process of transmitting a piece of information over a single line. A digital multiplexer (MUX) is a combinational circuit that selects one digital piece of information from several sources and transmits the selected information on a single output line. So, it also called a data selector. Since it selects one of many inputs and steers the information to the output.

The multiplexer has several data-input lines and a single output line. The selection of a particular input line controlled by a set of selection lines. The block diagram of a multiplexer with n input lines, m select signals and one output line shown below figure:

Multiplexer and Demultiplexer

The selection lines decide the number of input lines of a particular multiplexer. If the number of n input lines equal to 2m, then m selects the lines required to select one of the n input lines.


The word ‘demultiplex‘ means “one into many“. Demultiplexing is the process of taking information from one input and transmitting the same over one of several outputs. A demultiplexer is a logic circuit that receives information on a single input and transmits the same information over one of several (2m) output lines. The block diagram of a demultiplexer which is opposite to a multiplexer in its operation shown below figure:

Multiplexer and Demultiplexer

The circuit has one input signal, m select signals and n output signals. The selected inputs determine to which output the data input will be connected. As the serial data changed to parallel data, the input caused to appear on one of the n output lines. So, the demultiplexer also called a distributer or a serial-to-parallel converer.