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Difference between Multiplexer and Decoder
Both multiplexer and decoder are types of combinational digital circuits that are extensively used in the transfer of signals in many communication systems. Basically, the multiplexer and decoder both perform almost identical functions, however they are different from each other in many aspects.
The major difference between multiplexer and decoder is in their function that is the primary function of a multiplexer is to transmit data while the primary function of a decoder is to interpret a coded data.
In this article, we have enlisted all the significant differences between multiplexer and decoder in the table below.
What is Multiplexer?
The multiplexer or MUX is a combinational digital circuit which selects one of many input signals and transmit the selected input signal to a single output line. The multiplexer is also known as data selector as it selects one input from several inputs and delivers it to a single output line. The operational principle of the multiplexer is many-to-one.
The block diagram of a multiplexer is shown in Figure-1. In case of a multiplexer, there are 2n input data lines and 1 output line, where n is the number of select lines of the MUX used to provide the control signal to the circuit. Some common applications of multiplexer are data routing, waveform generation, etc.
What is Decoder?
A decoder is a combinational logic circuit which has many input and output lines. Therefore, a decoder has "n" input lines and maximum "m" output lines, where m = 2n. When the decoder circuit is enabled, based on the combination of inputs present, one of the 2n output lines will be active high. The block diagram of decoder is shown in Figure-2.
In case of a decoder, for each of the input combinations, there is exactly one output is true. Therefore, the decoder is also known as min-term generator or max-term generator. In context of binary codes, a decoder can also be defined as it is a logic circuit which takes "n" number of input binary code and converts it into a corresponding output signal.
The decoders are extensively used in several applications such as seven segment display, address decoding in memory systems, control units, networking and telecommunication systems, etc.
Difference between Multiplexer and Decoder
The multiplexer and decoder are combinational logic circuits having almost similar functions. However, both circuits are different from each other in many aspects, which are highlighted in the following table-
Basis of Difference | Multiplexer | Decoder |
|---|---|---|
Definition | A combinational logic circuit which has 2n input lines and only 1 output lines is called multiplexer or MUX. | A combinational logic circuit which has ‘n’ input lines and maximum 2n output lines is known as decoder. |
Operation | A multiplexer select one of the several inputs and transmits the selected input signal to a single output. | A decoder accepts n input binary codes and converts them into a corresponding output signal. |
Primary function | The main function of a multiplexer it to transmit the data and signal. | The main function of a decoder is to interpret the coded data. |
Controlling of operation | In multiplexer, the select lines are used to control the operation, i.e. the select lines determine that which input signal is allowed to pass to the output. | A decoder has an enable input which controls the operation of it. |
Input lines | Multiplexer has 2n input lines, where "n" is the number of select lines. | Decoder has "n" input lines. |
Output lines | There is only 1 output lines in case of multiplexer. | A decoder has 2n output lines. |
Types | Based on the number of input and output lines, the common types multiplexers are −
| Based on the number of input and outputs, the common types of decoders are −
|
Applications | Multiplexer is used in many applications such as communication systems, data routing, waveform generator, computer memories, etc. | Decoders are used in applications such as seven segment display, address decoding in memory systems, control units, networking and telecommunication systems, etc. |
Conclusion
Both multiplexer and decoder are types of combinational logic circuits. All the noticeable differences between multiplexer and decoder are enlisted in the above table. The most significant difference between multiplexer and decoder is that the multiplexer has many input lines and only one output line, whereas the decoder has many input lines (say "n") and many output lines (will be 2n).
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