Demultiplexer (DEMUX) select one output from the multiple output line and fetch the single input through selection line. It consist of 1 input and 2 power n output. The output data lines are controlled by n selection lines. For Example, if n = 2 then the demux will be of 1 to 4 mux with 1 input, 2 selection line and 4 output as shown below. Also VHDL Code for 1 to 4 Demux described below.