# what is Decoder?

hello friends! Today I am going to tell you about what is Decoder? and its types in this article. So let's start:-

## What is decoder?

Decoder is such a logic circuit that can identify each combination of signals given on its input. In this, taking n-input lines, there are 2n output lines.

For example:- If there are two binary lines in the input of the decoder then there will be four lines in the output of the decoder.

In other words, "a decoder is a circuit that converts a code into a set of signals." It is called decoder because it is the opposite of encoder.

## Types of Decoder

Its types are as follows:-

### 2 to 4 decoder

It has two input lines. Four combinations of input signals can be made from two lines – 00, 01, 10, and 11. For each of these combinations, one of the 4 output lines is HIGH and the rest of the lines are LOW.
For example:- If the input is 112, then the output line '3' is at logic '1' and the rest of the lines are at logic '0'. This action is called decoding. In the above picture you have been given the symbol of 2 to 4 decoder. It is also called 1 out of 4 decoder. Because in this only one line out of four output lines is on HIGH.

### 4 to 16 decoder

It has 4 input lines and 16 output lines. Its logic circuit is shown in the above figure. In which there are 4 control input (A, B, C, D) and 16 output lines.

No data input is given to this decoder, rather it is given input only in the form of control bits (ABCD). In this decoder, for any one combination of input, out of 16 output lines, one line is on 'HIGH' and the rest of the lines are on 'LOW'. That's why this decoder is also called 1 of 16 decoder.

## BCD to Decimal decoder

BCD to Decimal decoder has 4 input lines and 10 output lines. It is also called 1 of 10 decoder because out of its 10 output lines only 1 is on 'HIGH'. And the rest of the lines are on 'LOW'.

For example:- When the value of ABCD is 0100 then only output line 4 will be 'HIGH'.

## BCD to 7 segment decoder

7 segment LED display is widely used in digital systems. But to use it, BCD data needs to be changed. Therefore, BCD to 7 segment decoder is used to convert this data.

There are 4 input lines in the circuit of this decoder. By which BCD input is given. Decoder has 7 output lines which drive 7 segment display. And in this the output line of decoder is combined with 7 segment display.

In this, the output of the decoder can be either active LOW or active HIGH. 7 segment display can also be common cathode or common anode.