Decoders and Encoders

Decoders

Circuits used to decode an $n$-input signal into $2^n$ outputs

• A 'one-hot encoded' decoder is a decoder which only sets one output to 1 at a time

2-to-4 binary decoder

2i4o

Demultiplexers

A decoder can also be used as a 1-to-2^n demuxer.

This is used in TDM (time division multiplexing) circuits, which allow a single input to transfer data

Encoders

Encodes $2^n$ inputs into an $n-bit$ code

Priority Encoders

The higher the priority, the higher the input pin.

Uses an additional wire z to indicate whether an input is received

• Intermediate Signals

• Output