In electronics, a multiplexer or mux (occasionally the term muldex is also found, for a combination multiplexer-demultiplexer) is a device that performs multiplexing: it selects one of many analog or digital data sources and outputs that source into a single channel.
A demultiplexer (or demux) is a device taking a single input that selects one of many data-output-lines and connects the single input to the selected output line. A multiplexer is often used with a complementary demultiplexer on the receiving end.
An electronic multiplexer functions as multiple-input, single-output switch. A multiplexer has multiple inputs and a selector that connects a specific input to the single output.
The schematic symbol for a multiplexer is an isosceles trapezoid with the longer parallel side containing the input pins and the short parallel side containing the output pin. The schematic on the right shows a 2-to-1 multiplexer on the left and an equivalent switch on the right. The sel wire connects the desired input to the output.
In telecommunications, a multiplexor is a device that performs multiplexing, i.e. that combines multiple analog message signals or digital data streams into one signal.
In telecommunications and signal processing, an analog time division multiplexer may take several samples of separate analogue signals and combine them into one pulse amplitude modulated (PAM) wide-band analogue signal. Alternatively, a digital TDM multiplexer may combine a limited number of constant bit rate digital data streams into one data stream of a higher data rate, by forming data frames consting of one timeslot per channel.
In telecommunications and computer networks, a statistical multiplexer may combine several variable bit rate data streams into one constant bandwidth signal, for example by means of packet mode communication.
An inverse multiplexer may utilize several communication channels for transferring one signal.