# Circuit Design of 4 to 16 Decoder Using 3 to 8 Decoder

A decoder is a combinational circuit constructed with logic gates. It is the reverse of the encoder. A decoder circuit is used to transform a set of digital input signals into an equivalent decimal code of its output. For ‘n’ inputs a decoder gives 2^n outputs. In this article, we will discuss on 4 to 16 decoder circuit design using 3 to 8 decoder.

An encoder is a combinational circuit that changes a set of signals into a code. For ‘2^n’ inputs an encoder circuit gives ‘n’ outputs.

The following figure shows the block diagram of a decoder.

## 3 to 8 Decoder

This decoder circuit gives 8 logic outputs for 3 inputs. The circuit is designed with AND and NAND combinations. It takes 3 binary inputs and activates one of the eight outputs.

#### Circuit Diagram

The decoder circuit works only when the Enable pin is high.

#### Truth Table

When the Enable (E) pin is low, all the output pins are low.

 S0 S1 S2 E D0 D1 D2 D3 D4 D5 D6 D7 x x x 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 1 1 0 0 0 0 0 0 1 0 0 1 0 1 0 0 0 0 0 1 0 0 0 1 1 1 0 0 0 0 1 0 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 1 1 0 0 1 0 0 0 0 0 1 1 0 1 0 1 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0

### Circuit Design of 4 to 16 Decoder Using 3 to 8 Decoder

A decoder circuit of the higher combination is obtained by adding two or more lower combinational circuits. 4 to 16 decoder circuit is obtained from two 3 to 8 decoder circuits or three 2 to 4 decoder circuits.

When two 3 to 8 Decoder circuits are combined the enable pin acts as the input for both the decoders. When enable pin is high at one 3 to 8 decoder circuits then it is low at another 3 to 8 decoder circuit.

#### Truth Table

The Enable (E) pin acts as one of the input pins for both 3 to 8 decoder circuits.

 E A B C Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 Y10 Y11 Y12 Y13 Y14 Y15 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

#### Applications of Decoders

• In every wireless communication, data security is the main concern. The decoders are mainly designed to provide security for data communication by designing standard encryption and decryption algorithms.
• Decoders are used in audio systems to convert analogue audio into digital data.
• Used as a decompressor to convert compressed data like images and videos into decompressed form.
• Decoders use electronic circuits which convert computer instructions into CPU control signals.

Therefore, this is all about the 4 to 16 decoder circuit design using a 3 to 8 decoder circuit. Furthermore, any queries regarding this article or electronics projects you can comment us in the comment section below. here is a question for you, what is the use of Enable pin encoder/ decoder?