Both multiplexers and decoders play significant roles in the transfer of signals in many communication systems. Although they perform similar functions, there are notable differences between them.
What is a Multiplexer?
A multiplexer, also known as a MUX, is a combinational digital circuit that actively selects one input signal out of several options and transmits the chosen signal to a single output line. It functions as a data selector by picking a specific input from multiple inputs and delivering it to a designated output line. The operational principle of a multiplexer is based on the concept of merging multiple inputs into one output, following a many-to-one approach.
What is Decoder?
On the other hand, a decoder is another type of combinational logic circuit that consists of multiple input and output lines. A decoder typically has “n” input lines and a maximum of “m” output lines, where the value of “m” equals 2 to the power of “n” (m = 2^n). When the decoder circuit is enabled, it examines the combination of inputs present and activates one of the 2^n output lines accordingly. This means that only one specific output line will be active high based on the input combination. The block diagram of a decoder is illustrated in Figure 2.
Difference between Multiplexer and Decoder
Here is a simplified table highlighting the differences between a multiplexer and a decoder:
|Basis of Difference||Multiplexer||Decoder|
|Definition||A circuit with 2n inputs and 1 output.||A circuit with n inputs and a maximum of 2n outputs.|
|Operation||Selects one input and transmits it to the output.||Converts input codes into corresponding output signals.|
|Primary function||Transmits data and signals.||Interprets coded data.|
|Controlling of operation||Select lines control the operation, determining which input passes to the output.||Enable input controls the operation.|
|Input lines||Has 2n input lines.||Has n input lines.|
|Output lines||Has 1 output line.||Has 2n output lines.|
|Types||Common types include 8:1, 16:1, and 32:1 multiplexers.||Common types include 2:4, 3:8, and 4:16 decoders.|
|Applications||Used in communication systems, data routing, waveform generation, computer memories, etc.||Used in seven-segment displays, memory address decoding, control units, networking, telecommunication systems, etc.|
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