Multiplexers (MUX) 2-to-1 line MUX Implementation 4-to-1 line MUX Implementation MUX Symbols/Representation

1. Digital Design – © 2020 Mouli Sankaran Email: mouli.sankaran@yahoo.com

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Session 13: Focus
 Multiplexers (MUX)
◦ 2-to-1 line MUX Implementation
◦ 4-to-1 line MUX Implementation
◦ MUX Symbols/Representation

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Multiplexer (MUX)

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Multiplexer (MUX)
 A multiplexer (MUX) is a device that allows digital
information from several sources to be routed onto a
single line for transmission
 A basic MUX has several data-input lines and a
single output line
 It has data-select inputs, which permit digital data on
any one of the inputs to be switched to the output line
 Multiplexers are also known as data selectors

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2-to-1 line Multiplexer
 When S = 0, I0 will be available at Y
 When S = 1, I1 will be available at Y

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4–to-1 line Multiplexer

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Implementation: 4-to-1 line Multiplexer
D0
D1
D2
D3

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Quiz 1: Draw the Output Waveform
 Given the data-input and the data-select waveforms, draw the
output waveform

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Quadruple 2-to-1-line Multiplexer
 The circuit has four multiplexers, each capable of selecting one
of two input lines Outputs
Y3Y2Y1Y0
Inputs
B3A3 B2A2 B1A1 B0A0
S – Selector
Input
E – Enable
Signal
 What is the purpose of an Enable
signal here?
 To make sure that only when needed
(enabled) one of the dataset (either A
or B) is available at the output
 And not to have one of the
inputs at the output always

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Mux Symbols in Use
4-to-1 Line Mux
8-to-1 Line Mux

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Quiz 2: What are the values at the output (Q)?
D0
D1
D2
D3
S0
S1
S2
S2 S1 S0
Selectors Output
(Q)
D00 0 0
A
B
S Q
Function
Table
1 1 1 D3
1 0 1 D2
0 0 1 D1

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Session 13: Summary
 Multiplexers (MUX)
◦ 2-to-1 line MUX Implementation
◦ 4-to-1 line MUX Implementation
◦ MUX Symbols/Representation

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References
Ref 1 Ref 2