Multiplexers
A multiplexer has a number of inputs, a selector, and one output. The selector represents which of the inputs to output. Think of the inputs as an array, selector as an index, and the output as the result of that index.
The selector can be multiple bits to accommodate for many inputs.
2-1 Multiplexer
Symbol
Truth Table
| s | f |
|---|---|
| 0 | |
| 1 |
4-1 Multiplexer
Symbol
Truth Table
| f | ||
|---|---|---|
| 0 | 0 | |
| 0 | 1 | |
| 1 | 0 | |
| 1 | 1 |
Implementing 16-1 Multiplexer Using 4-1 Multiplexers
Implementation
Decoder Based Mux Design
De-Multiplexers
Symbol
Truth Table
| 0 | 0 | x | 0 | 0 | 0 |
| 0 | 1 | 0 | x | 0 | 0 |
| 1 | 0 | 0 | 0 | x | 0 |
| 1 | 1 | 0 | 0 | 0 | x |
Similar to a decoder, we have: