Editing Multiplexer (section)

{{Short description|Device that selects between several analog or digital input signals}}
{{About|electronics switching|telecommunications|multiplexing}}

[[File:Multiplexer2.svg|thumb|300px|Schematic of a 2-to-1 multiplexer. It can be equated to a controlled switch.]]
[[File:Demultiplexer.png|thumb|270px|Schematic of a 1-to-2 demultiplexer. Like a multiplexer, it can be equated to a controlled switch.]]

In [[electronics]], a '''multiplexer''' (or '''mux'''; spelled sometimes as '''multiplexor'''), also known as a '''data selector''', is a device that selects between several [[Analog signal|analog]] or [[Digital signal (electronics)|digital]] input signals and forwards the selected input to a single output line.<ref name="Network+ Guide to Networks">{{cite book | last = Dean | first = Tamara | title = Network+ Guide to Networks | publisher = Delmar | year = 2010 | pages = 82–85 | isbn = 978-1423902454 | url = https://books.google.com/books?id=UD0h_GqgbHgC&q=network%2B+guide+to+networks}}</ref> The selection is directed by a separate set of digital inputs known as select lines. A multiplexer of <math>2^n</math> inputs has <math>n</math> select lines, which are used to select which input line to send to the output.<ref>{{cite book | last = Debashis | first = De | title = Basic Electronics | publisher = Dorling Kindersley | year = 2010 | pages = 557 | isbn = 9788131710685 | url = https://books.google.com/books?id=mT_j4F1bJx4C&q=Basic+Electronics+By+De+Debashis}}</ref>

A multiplexer makes it possible for several input signals to share one device or resource, for example, one [[analog-to-digital converter]] or one communications [[transmission medium]], instead of having one device per input signal. Multiplexers can also be used to implement [[Boolean algebra|Boolean functions]] of multiple variables.

Conversely, a '''demultiplexer''' (or '''demux''') is a device that takes a single input signal and selectively forwards it to one of several output lines. A multiplexer is often used with a complementary demultiplexer on the receiving end.<ref name="Network+ Guide to Networks"/>

An electronic multiplexer can be considered as a [[System analysis#Characterization of systems|multiple-input, single-output]] switch, and a demultiplexer as a [[System analysis#Characterization of systems|single-input, multiple-output]] switch.<ref>{{cite book | last = Lipták | first = Béla | title = Instrument engineers' handbook: Process software and digital networks | publisher = CRC Press | year = 2002 | pages = 343 | isbn = 9781439863442 | url = https://books.google.com/books?id=KPjLAyA7HgoC&q=instrument+engineers'+handbook:+Process+software+and+digital+networks+By+B%C3%A9la+G.+Lipt%C3%A1k}}</ref> 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.<ref>{{cite book | last = Harris | first = David | title = Digital Design and Computer Architecture | publisher = Penrose | year = 2007 | pages = 79 | isbn = 9780080547060 | url = https://books.google.com/books?id=5X7JV5-n0FIC&q=Digital+design+and+computer+architecture+By+David+Money+Harris,+Sarah+L.+Harris}}</ref>  The schematic on the right shows a 2-to-1 multiplexer on the left and an equivalent switch on the right. The <math>sel</math> wire connects the desired input to the output.