The ebook FEEE - Fundamentals of Electrical Engineering and Electronics is based on material originally written by T.R. Kuphaldt and various co-authors. For more information please read the copyright pages.



Multiplexers

A multiplexer, abbreviated mux, is a device that has multiple inputs and one output.

The schematic symbol for multiplexers is

multiplexer schematic

The truth table for a 2-to-1 multiplexer is

multiplexer truth table

Using a 1-to-2 decoder as part of the circuit, we can express this circuit easily.

2-to-1 multiplexer circuit
2-to-1 multiplexer ladder

Multiplexers can also be expanded with the same naming conventions as demultiplexers. A 4-to-1 multiplexer circuit is

4-to-1 multiplexer

That is the formal definition of a multiplexer. Informally, there is a lot of confusion. Both demultiplexers and multiplexers have similar names, abbreviations, schematic symbols and circuits, so confusion is easy. The term multiplexer, and the abbreviation mux, are often used to also mean a demultiplexer, or a multiplexer and a demultiplexer working together. So when you hear about a multiplexer, it may mean something quite different.



Last Update: 2010-11-19