A multiplexer and demultiplexer allow multiple signals to share a single transmission line. A 2/1 multiplexer is described with a block diagram, truth table, and K-map implementation showing it selects one of two inputs based on a select line. A 4/1 multiplexer circuit is also shown. Multiplexers are used in data communications, radio channels, computer routing, and function generation by selecting an output from multiple inputs. An 8/1 multiplexer generates a function from a truth table. A 1 to 2 demultiplexer circuit separates a single input into two outputs based on a select line.

1. Representation of a
Dultiplexer and Demultiplexer
Explaining Their Types

2. Design of a 2/1 Mux
• 2/1 mux Block
Diagram
• Truth Table
D1
D0
S
O
S D1 D0 O
0 0 0 0
0 0 1 1
0 1 0 0
0 1 1 1
1 0 0 0
1 0 1 0
1 1 0 1
1 1 1 1

3. Design of 2/1 Mux Continued
• K-Map
SA
B
00 1101 10
0
1
1
1 1 1
O = S’A + SB

4. 4/1 Mux
• Circuit

5. Uses of Multiplexers
– Used in data communications for several
computers to communicate over 1 line
– Used in radio to select one channel from
many
– Used to route data within a computer
– Used for function generation

6. Function Generation using
Multiplexers
• Given the following
truth table use an 8/1
Mux to generate F
• Block Diagram
A B C F
0 0 0 0
0 0 1 0
0 1 0 1
0 1 1 0
1 0 0 0
1 0 1 1
1 1 0 1
0
0
0
0
1
1
1
1
A B C
S2 S0S1
F

7. Function Generation Continued
• Generate the previous F using a 4 to 1
Mux
0
C’
C
1
A B
F
S1 S0

8. 1 to 2 Demultiplexer
• Truth Table • Circuit
S D 01 O0
0 0 0 0
0 1 0 1
1 0 0 0
1 1 1 0