Designing of 2 to 4 Line Decoder

Before going into realities about Encoders and Decoders, let us have a concise thought regarding Multiplexing. Regularly we go over applications where it is expected to nourish a few input signals to a solitary load, each at once. This procedure of choosing one of the input signals to be fed to the load is known as Multiplexing. The invert of this operation, i.e. the way toward nourishing a few loads from one common signal source is known as Demultiplexing. Similarly in a digital domain, for simplicity of transmission of information, the information is regularly scrambled or set inside codes and afterward, this secured code is transmitted. At the collector, the coded information is decoded or accumulated from the code and is handled to be shown or given to the load likewise.

2 to 4 Line Decoder
2 to 4 Line Decoder

This assignment of encrypting the information and unscrambling the information is finished by Encoders and Decoders. So how about we now comprehend what are really Encoders and Decoders.

What is a Decoder?

A decoder is a multiple input, multiple output logic circuit that changes codes i/ps into coded o/ps, where both the inputs and outputs are dissimilar for instance n-to-2n, and binary coded decimal decoders. Decoding is essential in applications like data multiplexing, memory address decoding, and 7 segment display. The best example of decoder circuit would be an AND-gate because when all its inputs are “High.”, the output of this gate is “High” which is called “active High output”. As an alternative to AND gate, the NAND gate is connected the output will be “Low” (0) only when all its inputs are “High”. Such o/p is called “active low output”.


A slightly more difficult decoder would be the n-to-2n type binary decoders. These kinds of decoders are combinational circuits that modify binary information from n-coded inputs to a most of 2n exclusive outputs. In case then-bit coded data has idle bit combinations, the decoder may have less than 2n outputs. 2-to-4, 3-to-8 line decoder or 4-to-16 decoder are other examples.

The parallel binary number is an input to a decoder, used to notice the occurrence of a particular binary number at the input. The output shows existence or nonexistence of precise number at the decoder input.

Designing of 2 to 4 Line Decoder Circuit

Similar to the multiplexer circuit, the decoder is not restricted to a particular address line, and thus can have more than two outputs (with two, three, or four address lines). The decoder circuit can decode a 2, 3, or 4-bit binary number, or can decode up to 4, 8, or 16 time-multiplexed signals.

2-to-4-Decoder Circuit
2-to-4-Decoder Circuit

As a decoder, this circuit takes an n-bit binary number and generates an output on one of the 2n output lines. It is therefore usually described by the number of addressing i/p lines & the number of data o/p lines. Typical decoder ICs might include two 2-4 line circuits, a 3-8 line circuit, or a 4-16 line decoder circuit. One exclusion to the binary character of this circuit is the 4-10 line decoders, which is proposed to alter a Binary Coded Decimal (BCD) input to a 0-9 range output.

If you employ this circuit as a decoder, you may want to insert data latches at the o/ps to keep every signal while the others are being conveyed. But, this doesn’t relate when you are using this circuit as a decoder, then you will want just a single active o/p to equal the input code.

2 to 4 Line Decoder Truth Table

In this type of decoders, decoders have two inputs namely A0, A1, and four outputs denoted by D0, D1, D2, and D3. As you can see in the following truth table – for every input combination, one o/p line is turned on.

2-to-4-Decoder Truth Table
2-to-4-Decoder Truth Table

In the above example, you can observe that each o/p of the decoder is truly a minterm, resulting from an assured inputs combination, that is:

D0 =A1 A0, ( minterm m0) which corresponds to input 00 D1 =A1 A0, ( minterm m1) which corresponds to input 01 D2 =A1 A0, ( minterm m2) which corresponds to input 10 D3 =A1 A0, ( minterm m3) which corresponds to input 11

The circuit is implemented with AND gates, as shown in the figure. In this circuit, the logic equation for D0 is A1/A0, and so on. Thus, each output of the decoder will be generated to the input combination.

Applications of Decoder

The applications of decoder involve in the making of various electronic projects.

  • War- Field -Flying Robot with a Night Vision Flying Camera
  • Robotic Vehicle with Metal Detector
  • RF-based Home Automation System
  • Speed Synchronization of Multiple Motors in Industries
  • Automatic Wireless Health Monitoring System in Hospitals for Patients
  • Secret Code Enabled Secure Communication using RF Technology

This is all about decoder, and its applications in communication-based projects. We believe that you might have got a better idea of this concept. Furthermore, any doubts regarding this article, please give your precious suggestions by commenting on the comment section below.