Multiplexers/ Demultiplexers

1. Multiplexers/ Demultiplexers

2. Multiplexer • Combinational circuit that selects binary information from one of many input lines and directs information to a single output line.

3. Multiplexer ctd … • Selection inputs. • 2ninput lines. • n selection inputs. • Data selector • Selects one of many inputs and steers binary information to output line.

5. Function table

6. Decoders in Multiplexers • AND gates and inverters in multiplexer resemble a decoder circuit. • 2n - to – 1 line MUX is constructed from n-to- 2n decoder by adding 2n input lines. • MUX blocks can be combined in parallel with common selection & enable lines.

7. Quadruple 2-to-1 Line Multiplexer • 4 multiplexers • Each capable of selecting one of two input lines. 1A • 1Y 1B • Input selection line S selects one of lines in each of four MUXs. • Enable input E must be active for normal operations.

9. Demultiplexer • Inverse of MUX • Demultiplexer receives information from a single line and transmits it to one of 2n possible output lines. • Selection of specific output is controlled by bit combination of n selection lines.

10. Demultiplexer

11. Demultiplexer / Decoder • Identical to 2-to 4 line decoder with enable output.