Posted By on September 30, 2014

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A decoder is a combinational circuit. It has n input and to a maximum m = 2n outputs. Decoder is identical to a demultiplexer without any data input. It performs operations which are exactly opposite to those of an encoder.

Block diagram

Block Diagram of Decoder

Examples of Decoders are following.

  • Code converters
  • BCD to seven segment decoders
  • Nixie tube decoders
  • Relay actuator

2 to 4 Line Decoder

The block diagram of 2 to 4 line decoder is shown in the fig. A and B are the two inputs where D through D are the four outputs. Truth table explains the operations of a decoder. It shows that each output is 1 for only a specific combination of inputs.

Block diagram

Block Diagram of 2 to 4 Decoder

Truth Table

Truth Table of 2 to 4 Decoder

Logic Circuit

Logic Circuit of 2 to 4 Decoder


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Posted by Akash Kurup

Founder and C.E.O, World4Engineers Educationist and Entrepreneur by passion. Orator and blogger by hobby