What is Encoder?

An Encoder is a device that is used to change a signal (such as bitstream) or data into a code. The code may serve any of a number of purposes such as compressing information for transmission or storage, encrypting or adding redundancies to the input code, or translating from one code to another. Encoders perform a reverse operation from the decoder. So, an encoder will have 2n input lines that will be used to generate maximum of n output lines. If a device output code has fewer bits than the input code has, the device is usually called an encoder.

There are Four types of Encoder

  • Priority encoder.
  • Decimal to BCD encoder.
  • Octal to Binary encoder.
  • Hexadecimal to Binary encoder.

Two popular Encoder ICs

1. H12E

A popular example of an Encoder is the Holtek Encoder H12E used for parallel to serial conversion.

2. HC148

Another popular example of Encoder IC used as a priority Encoder is HC148 which is an 8 to 3 Line Priority Encoder. 

What is Decoder?

A decoder is a combinational circuit that converts a binary input of n variable into maximum of 2n unique output variables. Decoder can detect a code and activate a single output to signal the presence of that code. Block diagram to represent 3-to-8 decoder is given below-

Decoder have many applications, from producing system alerts in alarm systems to performing the task of driving multiple devices in microprocessor system (e.g. memory).

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