Multiplexer
Multiplexers are primarily thought of as "data selectors" because they select one of several inputs
to be logically connected to the output, they can also be used to implement Boolean functions. We
can implement any Boolean function of x variables using a 2x input MUX. Multiplexers can be used
more effectively by using some forms of functional decomposition; meaning we can implement a 4-
variable function using 8-to-1 MUX by using three of the variables as select inputs and feeding an
appropriate function of the fourth variable to the data inputs of the MUX.
Consider the following truth table that describes a function of 4 Boolean variables.
BCDF
A
0 0 0 0 0
0 0 0 1 1
0 0 1 0 1
0 0 1 1 1
0 1 0 0 1
0 1 0 1 0
0 1 1 0 0
0 1 1 1 0
1 0 0 0 0
1 0 0 1 0
1 0 1 0 0
1 0 1 1 0
1 1 0 0 0
1 1 0 1 0
1 1 1 0 0
1 1 1 1 1
logic 1
logic 0
MUX 16:1
Figure 3.2
17
A 16x1 MUX with A, B, C, and D applied to its S3, S2, S1, and S0 inputs respectively would select one of its
16 inputs for each of the 15 possible combinations of A, B, C, and D.
3.4 PRELIMINARY WORK
1. What is multiplexer? Explain.
2. Design a 3x8 decoder.
3.5 PROCEDURE
1. Implement the same function using 8-to-1 MUX. Choose to connect A, B, and C to the select lines of the
MUX, then we need to feed the MUX inputs with values that are function of D. (Feed 16th pin of MUX
with SV and connect 8th pin to the ground.)
2. Draw the circuit to your report
