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# Difference Between Encoder and Decoder in Digital Logic

Last Updated on April 17, 2023 by Prepbytes

Encoder and decoder are combinational logic circuits. Combinational logic refers to the idea that the output of the circuit depends only on the current values of the inputs, and not on the previous inputs or the circuit’s internal state. The encoder and decoder use boolean algebra to implement combinational logic. Encoder and decoder are widely used in digital systems, such as computer memory, digital communication systems, and computer peripherals. They play an essential role in converting binary and other forms of digital representation and are critical components in many digital circuits and systems.

## Encoder

An encoder is a digital circuit that utilizes combinational logic to change binary data from n-input lines into a smaller set of m-output lines, where m is less than n. The encoding process maps multiple input combinations to unique output combinations and is commonly used in digital systems to reduce the number of input lines required to represent a large set of binary values.
For example, a binary encoder takes a multi-bit input and converts it into a unique code of fewer bits. This is useful for compressing data and reducing the number of required inputs to a system. A common application of encoders is in computer memory, where they are used to encode addresses to access specific memory locations.
Encoder in Digital Electronics is implemented using the AND gates and OR Gates. The exact design of the encoder will depend on the specific encoding algorithm and the number of input and output lines

## Decoder

Decoder is just the opposite of the encoder. It converts coded information from one format into another format. They are commonly used for performing functions such as memory address decoding, data demultiplexing, and digital-to-analog conversion.
In memory address decoding, a decoder is used to convert binary addresses into specific memory locations, allowing the processor to access specific data stored in the memory. In data demultiplexing, a decoder is used to distribute one data input to multiple outputs, based on the input signal. This allows multiple signals to be transmitted over a single communication line.
Decoders are used in analog to digital converters. In this case, a decoder is used to convert digital signals into analog signals that can be used to control analog devices. Decoders can be implemented using a variety of digital logic circuits such as AND gates, OR gates, NOT gates, and NAND gates.

## Difference between Encoder and Decoder

As mentioned above encoder and decoder are exact different from each other in terms of functioning. The given table summarizes the difference between the encoder and decoder in detail.

Basis             Encoder          Decoder
Purpose Maps multiple inputs to a smaller representation Maps a smaller representation back to the original inputs
Operation Fixed, outputs are determined by the input combination Dynamic, outputs can change based on the input code
Application Compression, encoding, error correction, D/A conversion, address decoding Expansion, decoding, A/D conversion, demultiplexing, address decoding
Number of inputs and outputs: Input lines are 2^n, Output lines are n Input lines are n, Output lines are 2^n
Data flow Parallel to serial Serial to parallel
Efficiency High, compact representation of data reduces transmission time Depends on the implementation, may have a higher overhead
Flexibilty Limited, output representation is determined by the input combination High, can be designed to handle different input codes
Reprsentation Compact Expanded

## Implementation of Encoder and Decoder

Implementation of an encoder and decoder in digital signal processing typically involves the following steps:

### Encoder Implementation

• Sampling: The analog signal is sampled at regular intervals to obtain a series of discrete values.
• Quantization: The discrete values are quantized, or mapped to a finite set of numerical values, to reduce the number of bits required to represent the signal.
• Compression: The quantized values are compressed to reduce the size of the data for efficient transmission or storage. This can be achieved using lossless or lossy compression algorithms, depending on the desired level of compression and the acceptable level of data loss.

### Decoder Implementation

• Decompression: The compressed data is decompressed to reconstruct the quantized values.
• Dequantization: The quantized values are dequantized to obtain an approximation of the original discrete values.
• Reconstruction: The discrete values are reconstructed to obtain an approximation of the original analog signal.

It's worth noting that the exact implementation details of an encoder and decoder in digital signal processing will vary depending on the specific signal and application. Different encoding and decoding algorithms may use different techniques for sampling, quantization, compression, and reconstruction, tailored to the specific requirements of the signal and the system.

## Application of Encoder and Decoder

Encoder and decoder are widely used in many applications in digital circuits and systems, including:

• Computer Memory: Encoders are used to encode addresses in computer memory, allowing for efficient access to specific memory locations. Decoders are used to decode the encoded addresses and access the corresponding memory locations.
• Digital Communication Systems: Encoder and Decoder are used in the Digital Communication Systems for the interconversion of signals so that they can be transferred from one place to another.
• Computer Peripherals: Encoders are used in computer peripherals, such as keyboards and mice, to encode user inputs and transmit them to the computer. Decoders are used to decode the encoded inputs and interpret them in the computer.
• Robotics and Automation: Encoders are used in robotics and automation systems to encode and decode positional information, allowing for precise control of motors and actuators.
• Data Compression: Encoders are used in data compression algorithms to reduce the size of data for efficient transmission or storage. Decoders are used to decompress the compressed data and reconstruct the original data.
• Digital Signal Processing: Encoders are used in digital signal processing to quantize and compress signals, allowing for efficient processing and analysis. Decoders are used to dequantize and decompress the signals and reconstruct the original data.
• Display Technology: Encoder and Decoder are used in display technology, such as televisions and computer monitors, to encode and decode video signals.

So these are some of the major applications of encoder and decoder.

Summary
Encoder and decoder are fundamental building blocks in digital circuits and play a crucial role in converting digital signals from one format to another. An encoder is a digital circuit that converts information from multiple inputs into a coded format that can be transmitted or stored more efficiently. Encoders are commonly used in applications such as data compression, error correction, and digital-to-analog conversion.
A decoder, on the other hand, is a digital circuit that performs the reverse operation of an encoder, converting coded information into multiple outputs. Decoders are used in applications such as memory address decoding, data demultiplexing, and digital-to-analog conversion. In memory address decoding, a decoder is used to convert binary addresses into specific memory locations, allowing the processor to access specific data stored in the memory. In data demultiplexing, a decoder is used to distribute one data input to multiple outputs, based on the input signal.

Encoder and decoder can be implemented using different digital logic circuits such as AND gates, OR gates, NOT gates, and NAND gates. The choice of encoder or decoder size and type depends on the specific requirements of the application. Encoder and decoder are widely used in a variety of digital systems such as computers, communication systems, and digital control systems.

Encoder and decoder play a crucial role in converting digital signals from one format to another, allowing for efficient data storage and transmission. Their applications range from simple data compression to complex memory address decoding, and they are widely used in a variety of digital systems.

## FAQs Related to Encoder and Decoder

Here are some frequently asked questions (FAQs) related to the encoder and decoder.

Question 1: What is an encoder in digital circuits?
Answer: An encoder is a digital circuit that converts information from multiple inputs into a coded format that can be transmitted or stored more efficiently.

Question 2: What are the applications of encoders in digital circuits?
Answer: Encoders are used in a variety of applications such as data compression, error correction, and digital-to-analog conversion.

Question 3:What is a decoder in digital circuits?
Answer: A decoder is a digital circuit that performs the reverse operation of an encoder, converting coded information into multiple outputs.

Question 4: What are the applications of decoders in digital circuits?
Answer: Decoders are used in applications such as memory address decoding, data demultiplexing, and digital-to-analog conversion.

Question 5: How are encoders and decoders implemented in digital circuits?
Answer: Encoders and decoders can be implemented using different digital logic circuits such as AND gates, OR gates, NOT gates, and NAND gates.

Question 6: What factors determine the size and type of encoders and decoders in digital circuits?
Answer: The choice of encoder or decoder size and type depends on the specific requirements of the application.