Demultiplexers

A demultiplexer(DEMUX) performs the reverse operation of a multiplexer. It takes input from one line and distributes it to a given number of output lines. It is also known as data distributor. A demultiplexer with 2n output lines should have n data-selector lines.

1:4 Demultiplexer

A 1:4 demultiplexer takes input from one line and distributes it to 4 output lines. It has 2 data selector lines.

Figure shows a 1:4 demultiplexer.

1 4 demultiplexer 1

The data input lines goes to all of the AND gates. The two data-selector lines enable only one gate at a time based on its value.

if S1=0 and S0=0 then the data input is distributed to D0 output line and the value of all other output lines will be 0.

The operation of a 1:4 demultiplexer is described in the truth table.

Data Selector Outputs
S1 S0 D0 D1 D2 D3
0 0 D 0 0 0
0 1 0 D 0 0
1 0 0 0 D 0
1 1 0 0 0 D