18. Four-input Multiplexer

Multiplexers are not limited to two data inputs.

If two addressing inputs used, we can multiplex up to four data signals.

With three addressing inputs, we can multiplex eight signals, and so on.

Four-input multiplexer is a digital circuit that combines four input signals, one of which is selected by two separate address inputs to be sent to the single output.

The number of signal inputs is equal to 2^k, where k is the number of addressing inputs.

As the number of inputs increases, so is the number of selectors that are required for the mux to operate.