Page 82 - Handout Digital Electronics
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LECTURER 10 COMBINATIONAL LOGIC CIRCUITS BUILDING BLOCKS
10.1 Multiplexers
A multiplexer (MUX) is a logic circuit (electronic device) that combines two or more inputs into a
single output line. The are several types of multiplexers but in digital signal processing, a multiplexer
selects data from several input lines, combining the data using one of the three popular techniques (
Frequency division Multiplexing, Time Division Multiplexing and Statistical Time Division
Multiplexing)to a high-speed output line.
Figure 19: Symbol of a 4-1 multiplexer
As can be seen from the block diagram, a multiplexer connects multiple inputs to a single output. At any
one given time only one input is selected with data to be passed to the output. The input lines are D0,
D1, D2 and D3. To select any one of these input lines to pass data to the output F, the control settings A
and B are used. If A = 0 and B = 0, then the input line D0 will be selected to transmit data to the output
F. The data that would appear at output F is either a binary one (1) or a binary zero (0). This is because
binary bits are used.
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