Multiplexers

However, higher level multiplexers receive frames from lower level multiplexers with clocks whose value fluctuates around a nominal frequency value within certain margins of tolerance.

Add-drop multiplexer Add-drop multiplexers (ADMs) are the most common type of network elements.

Digital multiplexers In digital circuit design, the selector wires are of digital value.

For example, an 8-to-1 multiplexer can be made with two 4-to-1 and one 2-to-1 multiplexers.

In larger multiplexers, the number of selector pins is equal to where is the number of inputs.

In the design of digital multiplex hierarchies, care must be exercised to ensure interoperability of the multiplexers used in the hierarchy.

Multiplexers can also be used to implement Boolean functions of multiple variables.

Note that, as with multiplexers, links are often used in bi-directional pairs and, at either end of the link, an inverse multiplexer will be combined with its reverse (an inverse demultiplexer) and still be called an inverse MUX.

Note that the use of 3-state logic for bus systems is not needed, and can be replaced by digital multiplexers, which can be built using only simple logic gates (such as NAND gates, NOR gates, or AND and OR gates).

One use for multiplexers is cost saving by connecting a multiplexer and a demultiplexer together over a single channel (by connecting the multiplexer's single output to the demultiplexer's single input).

The first-ever fiber optic switching devices that allowed for switching were called Undersea Branching Multiplexers (UBMs).