In a 3-to-8 decoder, how many outputs are active for any given input?

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RRB JE ECE 22 Apr 2025 Shift 2 CBT 2 Official Paper
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  1. 2
  2. 8
  3. 3
  4. 1

Answer (Detailed Solution Below)

Option 4 : 1
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The correct option is 4

  • For any given 3-bit input, the decoder activates exactly one output line corresponding to that input's binary value.
  • All other outputs remain inactive (typically logic 0).

Concept:

  • A decoder is a combinational logic constructed with logic gates.
  • It is the reverse of the encoder.
  • A decoder circuit is used to transform a set of digital input signals into an equivalent decimal code of its output. For ‘n’ inputs a decoder gives ‘2n’ outputs.
  • Block diagram of the Decoder is shown below:

 

F1 T.S Madhu 21.07.20 D 5

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