Demultiplexers, often abbreviated as DEMUX, are digital electronic devices that perform the opposite function of multiplexers. They take a single input and route it to one of many possible output lines based on control signals. Demultiplexers are commonly used in digital systems for signal distribution, address decoding, and data demultiplexing purposes.
A demultiplexer has two main components: select lines and output lines. The select lines determine which output line the input signal is routed to.
How a demultiplexer works:
- Select Lines: A demultiplexer has a set of select lines, denoted as S0, S1, …, Sm-1, where m is the number of select lines. The select lines determine which output line the input signal is directed to.
- Control Signals: The select lines of the demultiplexer are driven by control signals. The control signals specify the binary code that determines the output line to which the input signal is routed. Each combination of select line values corresponds to a specific output line.
- Input Line: The demultiplexer has a single input line, denoted as D, which carries the input signal to be distributed to the output lines.
- Output Lines: A demultiplexer has multiple output lines, typically denoted as Y0, Y1, Y2, …, Yn-1, where n is the number of output lines. The output lines are the channels through which the input signal is distributed based on the control signals.
The operation of a demultiplexer can be understood using a truth table or a logic diagram. The truth table shows the relationship between the select lines, input line, and output lines. The logic diagram represents the internal circuitry of the demultiplexer, showing how the select lines control the routing of the input signal to the specific output line.
The number of select lines in a demultiplexer is given by m = log2(n), where n is the number of output lines. For example, a 1-to-4 demultiplexer would require 2 select lines. The output line to which the input signal is routed is determined by the binary value represented by the select lines.
Demultiplexers are commonly used in various applications, such as address decoding for memory systems, data demultiplexing in communication systems, and signal distribution in digital circuits. They provide a means to distribute a single input signal to multiple output lines based on control inputs.