A multiplexer, also known as a data selector, is a combinational circuit that selects data from multiple inputs and forwards one of them to a single output line based on the select signals. It has N input lines, M select lines, and one output line. The select inputs determine which input line is selected and forwarded to the output line.
The most commonly used multiplexer is the 2-to-1 multiplexer, which selects between two input lines based on the value of the select input. The implementation of a 2-to-1 multiplexer is shown below:
In this circuit, there are two input lines A0 and A1, one output line Y, and a select input (S). The select input controls the selection of the input line to be forwarded to the output line, with S=0 selecting input line A0 and S=1 selecting input line A1.
The implementation of a 4-to-1 multiplexer is shown below:
In this circuit, there are n input lines A0 to A3, one output line Y, and n select input lines S0 to S1. The select inputs are used to determine which input line is selected and forwarded to the output line. The multiplexer selects one of the input lines based on the binary value of the select inputs.
Multiplexers have various applications in digital circuits, such as data transmission, digital signal processing, and data storage. They can also be used as an address decoder in memory and input/output devices.