What is a Demultiplexer | Working, Types and Applications

Integrated circuits (ICs) offer various input/output configurations for demultiplexers, making them versatile components in digital circuitry. This article delves into the details of demultiplexers, exploring their definition, types of demultiplexer, such as 1-2 demultiplexer, 1-4 demultiplexer, and 1-8 demultiplexer, and 1-16 demultiplexer. We also discuss the practical applications of demultiplexer. And the advantages of demultiplexer as well as disadvantages of demultiplexer.

Demultiplexers play a crucial role in various digital applications, such as memory address decoding, communication systems, and digital signal processing. They facilitate the distribution of a single input signal to multiple outputs or the connection of multiple devices to a single output line. what is a demultiplexing  – The process of extracting information from a single input and transmitting it over one of many outputs is known as Demultiplexing, contrasting with the concept of Multiplexing discussed in the Multiplexer tutorial.

Introduction

Demultiplexers, also known as demux or data selectors, function as the inverse of multiplexers. While multiplexers take multiple inputs and select one output, demultiplexers take a single input signal and route it to one of several output lines based on control signals. These digital circuits are commonly used in Boolean function generators and decoder circuits.

Demultiplexers have their own schematic symbol. Symbol of demultiplexer –  Represents with a combinational circuit with one input line and 2N output lines. In essence, a demultiplexer serves as the opposite of a multiplexer, directing information from a single input to a chosen output based on selection lines.

What is a Demultiplexer?

A demultiplexer, commonly referred to as Demux or data selector, is a digital circuit that utilizes control signals to direct a single input signal to one of several output lines. Demultiplexers with 2n outputs incorporate n select lines to determine which output line receives the signal. These demultiplexers are also recognized as data distributors.

What is a Demultiplexer – A demultiplexer, sometimes abbreviated as dmux, features one input and multiple outputs. It proves useful when a circuit needs to transmit a signal to one of several devices. While this might seem similar to a decoder, it’s essential to distinguish between the two: a decoder selects among devices, whereas a demultiplexer sends a signal to multiple devices.

 

Unlike encoders and decoders, demultiplexers have n selection lines and 2n outputs, allowing for 2n possible input combinations. They are commonly referred to as demux as well. The key component of a demultiplexer is a binary decoder, which employs control signals to determine the activated output line. For instance, a 1-to-4 demultiplexer features one input line and four output lines, with data from the input forwarded to the selected output line dictated by control signals.

Types of Demultiplexer

There are various types of demultiplexers designed to accommodate different output configurations, such as 1-2 demultiplexer, 1-4 demultiplexer, 1-8 demultiplexer, and 1-16 demultiplexer. These demultiplexers come in diverse integrated circuit (IC) packages. Notable examples include the 74139 IC, which serves as a dual 1-4 demultiplexer, the 74138 IC, designed for 1-8 demultiplexing, the 74237 IC, functioning as a 1-8 demultiplexer with address lines, the 74154 IC, operating as a 1-16 demultiplexer, and the 74159 IC, serving as a 1-16 open collector demultiplexer. Consequently, these demultiplexer ICs are commonly referred to as decoder ICs. Here we discussed all types of demultiplexer in breif:

• 1-2 demultiplexer
• 1-4 demultiplexer
• 1-8 demultiplexer
• 1-16 demultiplexer

1-2 Demultiplexer

Within the configuration of a 1-2 demultiplexer, the fundamental components include a singular input line, facilitating the transmission of data, and two distinct output lines where the data can be directed. The 1-2 demultiplexer is a type of demultiplexer which integrates a select line, designated for the purpose of toggling or switching the input to either of the two output lines. The diagram illustrating the internal structure of this 1-2 demultiplexer is presented below, with the noteworthy addition of an enable input. This enable input acts as a control mechanism, influencing the functionality of the demultiplexer based on its state, thereby enhancing the flexibility and control over data routing within the demultiplexing process.

 

1-4 Demultiplexer

There are a total of four outputs in the 1-4 Demultiplexer, namely Y0, Y1, Y2, and Y3, two selection lines, namely S0 and S1, and a single input, namely A. A connection between an input and an output is made based on the combination of inputs that are present at the selection lines S0 and S1. Following are the 1-4 demultiplexer’s block diagram.

 

1-8 Demultiplexer

The 1-8 demultiplexer is a type of demultiplexer, which comprises a total of eight outputs, identified as Y0 through Y7, three selection lines denoted as S0 through S2, and a solitary input labeled A. The mechanism for connecting the input to a specific output relies on the unique combination of signals present at the selection lines S0, S1, and S2. In essence, the input A is directed to one of the eight outputs based on the particular configuration set by the selection lines.

1-16 Demultiplexer

To create a 1-16 demultiplexer, a combination of a 1-8 demultiplexer and a 1-2 demultiplexer can be employed. The 1-16 demultiplexer is characterized by a single input, four selection lines (S0 to S3), and a total of sixteen outputs labeled O0 through O15. Its primary function involves directing the signal from the single input line to a specific output line among O0 to O15, and this routing is determined by the configuration of the four selection lines. In essence, the 1-16 demultiplexer is the type of demultiplexer, which leverages the collaborative operation of the 1×8 and 1×2 demultiplexers to achieve its comprehensive output distribution.

 

How Demultiplexer Works?

A demultiplexer, often referred to as a demux, is a digital circuit that takes a single input signal and directs it to one of several output lines based on the state of its control lines. Demultiplexers are the reverse of multiplexers, which take multiple inputs and combine them into a single output.

Here’s a general overview of how a demultiplexer works:

• Input and Control Line: The demultiplexer features a single input line (A) and multiple output lines (Y0 to Yn). Control lines (S0 to Sn) dictate the output selection, directing the input signal to a specific line. This configuration ensures flexible signal distribution within digital circuits, enhancing the versatility of the demultiplexer in various applications.
• Control Line Configuration: The number of control lines depends on the specific demultiplexer configuration. For example, a 1-to-2 demultiplexer has one control line (S0), a 1-to-4 demultiplexer has two control lines (S0 and S1), and so on.
• Output Selection: The binary state of the control lines determines which output line will receive the input signal. Each unique combination of control line states corresponds to a specific output.
• Routing the Input: The demultiplexer routes the input signal to the selected output line based on the configuration set by the control lines.
• Block Diagram: The demultiplexer’s block diagram illustrates the connections between the input, control lines, and multiple outputs. It provides a visual representation of how the demultiplexer functions internally.
• Truth Table: A truth table outlines the relationship between the input, control lines, and output lines. It enumerates all possible input and control line combinations and specifies the corresponding output.

Demultiplexer takes a single input and, based on the configuration set by its control lines, directs the input to a specific output line. This functionality is crucial in digital circuitry for tasks such as data routing, signal demultiplexing, and decoding. Demultiplexers are used in various electronic systems to manage and distribute digital signals.

Applications of Demultiplexer

Demultiplexers play a pivotal role in microprocessor and computer control systems where the need arises to selectively choose or enable one signal from a multitude of options. The applications of demultiplexer extends to various crucial functions, including:

• Data Routing: They play a crucial role in selecting different input/output (IO) devices, optimizing data transfer efficiency.
• Memory Decoding: Demultiplexers aid in choosing specific memory banks based on their configuration, enhancing memory decoding processes.
• Synchronous Data Transmission Systems: In data transmission, demultiplexers contribute to the synchronization of processes, ensuring efficient and synchronized data flow.
• Automatic Test Equipment Systems: Demultiplexers support automated testing procedures in electronic systems, streamlining and improving the efficiency of testing processes.
• Security Monitoring Systems: By enabling the selection of specific surveillance cameras at designated times, demultiplexers contribute significantly to effective security monitoring in various environments.

The applications of demultiplexers makes them indispensable in a wide array of applications, showcasing their significance in the realm of digital systems and electronic control.

Advantages of Demultiplexer

Demultiplexers offer several advantages in various applications. Here are some common advantages of demultiplexer:

1. Signal Separation: Demultiplexers excel at separating combined or multiplexed signals, splitting them into distinct streams. This is particularly useful in scenarios where mutual signals need to be processed individually.
2. Complementary Function to Multiplexers: Demultiplexers serve as the counterpart to multiplexers, providing the reverse function by distributing signals instead of combining them. This duality enhances their utility in diverse signal processing tasks.
3. Security Systems Integration: In security systems, demultiplexers function as essential decoders, playing a key role in the disentanglement and interpretation of signals. This capability is crucial for effective surveillance and monitoring.
4. Audio and Video Signal Transmission: Mux (Multiplexer) and Demux (Demultiplexer) combinations are instrumental in transmitting audio and video signals. Demultiplexers specifically aid in unraveling these signals at the receiving end, ensuring accurate and separate reproduction.
5. Enhanced Communication Systems: When used in conjunction with multiplexers, demultiplexers contribute to the improvement of communication systems. This combination enables the efficient management of multiple signals, optimizing the overall communication process.

In summary, advantages of demultiplexers provide versatile solutions by untangling multiplexed signals, offering reverse functionality to multiplexers, facilitating security system integration, enabling efficient audio and video signal transmission, and enhancing communication systems when used in tandem with multiplexers.

Disadvantage of Demultiplexer

Exploring the disadvantage of demultiplexers reveals certain limitations:

Bandwidth Loss: A notable disadvantage associated with demultiplexers is the potential for bandwidth loss. The process of separating signals using a demultiplexer may lead to a reduction in available bandwidth. This reduction can impact the overall efficiency of data transmission, requiring careful consideration of bandwidth management in applications utilizing demultiplexers.

Signal Synchronization Delays:

Another disadvantage of multiplexer involves the possibility of delays due to the synchronization of signals. The process of demultiplexing, particularly in scenarios with multiple signals, may introduce delays as the system works to synchronize and distribute the signals to their respective outputs. Managing these delays becomes crucial in applications where real-time responsiveness is essential.