4-to 1 multiplexer circuit diagram


A multiplexer is a combinational circuit that receives binary information from one of 2n input data lines and directs it to a single output line. The selection of a particular input data line for the output is determined by a set of selection inputs. A 2n-to-1 multiplexer has 2n input data lines and n input selection lines whose bit combinations determine which input data selected for the output.

4-to 1 multiplexer:

Each of the four data inputs I0 through I applied to one input of an AND gate. The two selection inputs 51 and 50 are decoded to select a particular AND gate. The outputs of the AND gates applied to a single OR gate to provide the single output.

To demonstrate the circuit operation, consider the case when 5150 = 10. The AND gate associated with the input I have two of its inputs equal to 1. The third input of the gate connected to I2• The other three AND gates have at least one input equal to 0, which makes their outputs equal to 0. The OR gate output is now equal to the value of I, thus providing a path from the selected input to the output. A 4-to-1-line multiplexer shown below figure:


The 4-to-1 line multiplexer has six inputs and one output. A truth table describing the circuit needs 64 rows since six input variables can have 26 binary combinations. This is an excessively long table and will not be shown here. A more convenient way to describe the operation of multiplexers is by utilizing a function table.