Multiplexers And Demultiplexers

Multiplexers (a.k.a. a MUX or data selector) are integrated circuits which can be used to select one of many input signals and connect it to a single output signal. A demultiplexer does the reverse, it connects a single input signal to one of many output signals.

Analogue multiplexers pass an analogue signals from one of many inputs to a single output. Whilst a digital multiplexer buffers and amplifies the output, an analogue multiplexer does not, you can simply view it as a simple switched connection between input and output (albeit with a larger resistance than a mechanical switch). For this reason, analogue multiplexers are bidirectional (signals can pass from input to output, as well as pass from output to input), whilst digital multiplexers are single direction only (from input to output).

It’s important to note that most analogue multiplexers have a much higher resistance than a traditional mechanical switch or even transistor, with most specifying an on-state resistance (max) between \(30\) and \(150\Omega\).