Last Updated on March 20, 2023 by Prepbytes
Multiplexer, also known as MUX, are essential components in digital electronics. Multiplexer in digital electronics is widely used for data selection, signal routing, and address decoding in microprocessors and microcontrollers. They are also used in communication systems to transmit multiple signals over a single channel. This article will teach us about Multiplexing, a fascinating idea in communication, and its digital application called the Multiplexer in digital electronics. We will learn what exactly is multiplexer in digital electronics and the types of a multiplexer in digital electronics such as 2 to 1, 4 to 1, 8 to 1, and 16 to 1, and at the end of the article, we will also discuss what are the advantages and applications of a multiplexer in digital electronics.
What is Multiplexing?
Multiplexing is the process of transmitting multiple signals or data streams over a single communication channel or transmission medium. This is achieved by combining multiple input signals into a single output signal and then transmitting it over a shared communication channel.
Multiplexing is commonly used in communication systems to increase the capacity of a channel and improve the efficiency of data transmission. By transmitting multiple signals over a single channel, the bandwidth utilization is maximized, and the cost and complexity of communication systems are reduced.
There are several types of multiplexing techniques used in digital communication systems, including:
Time Division Multiplexing (TDM):
TDM is a technique where multiple signals are transmitted one after the other over a single channel. Each signal is assigned a time slot or time interval, and the channel is shared among the signals in a cyclical manner.
Frequency Division Multiplexing (FDM):
FDM is a technique where multiple signals are transmitted simultaneously over a single channel by dividing the frequency spectrum of the channel into multiple frequency bands, each band carrying a different signal.
Wavelength Division Multiplexing (WDM):
WDM is a technique where multiple optical signals are transmitted simultaneously over a single optical fiber by assigning each signal a different wavelength of light.
What is a Multiplexer in Digital Electronics?
A multiplexer in digital electronics is known as a data selector. It is a Combinational Logic Circuit having multiple input lines, one output line, and many select/control lines. It receives binary information from several input lines and routes it to a single output line based on a set of select/control lines. Multiplexer in digital electronics is also known as many-to-one combinational circuits.
The block diagram below depicts a multiplexer with n input lines, m selection lines, and one output line. If there are m selection/control lines, the number of possible input lines is 2m. Similarly, if the number of input lines is 2m, then m selection/control lines are required to select one of n (consider 2m = n) input lines.
Types of Multiplexers in Digital Electronics
There are several types of multiplexers in digital electronics, which are as follows:
A 2×1 multiplexer is a combinational logic circuit that has only two inputs, i.e, A0 and A1, 1 selection line, i.e., S0, and single outputs, i.e., Y. On the basis of the combination of inputs that are present at the selection line S0, one of these 2 inputs forwards to the output line. It is the simplest type of multiplexer in digital electronics. The 2X1 multiplexer’s block diagram and truth table are shown below.
A 4×1 multiplexer is a combinational logic circuit that selects one input from four inputs, i.e., A0, A1, A2, and A3 forwards it to the output line, i.e., Y based on the two control signal or selection lines, i.e., S0 and S1. The 4X1 multiplexer’s block diagram and truth table are shown below.
An 8×1 multiplexer is a combinational logic circuit that selects one input from eight inputs and forwards it to the output line based on the control signal or selection lines. It consists of eight input lines, one output line, and three selection lines. The 8X1 multiplexer’s block diagram and truth table are shown below.
8X1 Multiplexer using 4X1 and 2X1 Multiplexer
We can use a lower-order multiplexer to implement the 8X1 multiplexer. We need two 4X1 multiplexers and one 2X1 multiplexer to implement the 8X1 multiplexer. There are two selection lines, four inputs, and one output on the 4X1 multiplexer. There is only one selection line on the 2X1.
Two 4X1 multiplexers are required to receive 8 data inputs. The 4X1 multiplexer generates a single output. Thus we need a 2X1 multiplexer to get the final output. The block diagram of an 8X1 multiplexer made up of 4X1 and 2X1 multiplexers is shown below.
The 16 to 1 multiplexer has 16 inputs (A0, A1,…, A16), 4 selection lines (S0, S1, S2, and S3), and a single output (Y). Based on the combination of inputs present at the selection lines S0, S1, and S2, one of these 16 inputs will be connected to the output. The 16X1 multiplexer’s block diagram and truth table are shown below.
16X1 Multiplexer using 8X1 and 2X1 Multiplexer
We can use a lower-order multiplexer to construct the 16X1 multiplexer. Two 8X1 multiplexers and one 2X1 multiplexer are required to implement the 8X1 multiplexer. The 8X1 multiplexer has three selection lines, four inputs, and one output. There is only one selection line on the 2×1.
We need two 8X1 multiplexers to get 16 data inputs. The 8X1 multiplexer generates a single output. Thus, a 2X1 multiplexer is required to obtain the final output. The following is a block diagram of a 16X1 multiplexer made up of 8X1 and 2X1 multiplexers.
Advantages of Multiplexer in Digital Electronics
There are several advantages of Multiplexers in digital electronics:-
- Efficient use of resources: Multiplexers allow multiple input signals to be selected and transmitted over a single line, reducing the number of required output lines and thereby saving space on a printed circuit board.
- Simplified circuit design: Using a multiplexer can simplify the design of a digital circuit by reducing the number of gates and components required. This can lead to lower power consumption, less heat generated, and better reliability.
- Fast switching: Multiplexers can switch between multiple input signals very quickly, enabling fast data transfer and reducing delay in digital systems.
- Cost-effective: Multiplexers are relatively inexpensive and readily available, making them an economical choice for many digital applications.
Applications of Multiplexer in Digital Electronics
Multiplexers in digital electronics have a wide range of applications, including:
- Data routing and selection: Multiplexers are used to select and route data from multiple sources to a single destination. This is commonly used in digital communication systems to transmit multiple signals over a single channel.
- Signal processing and control: Multiplexers are used in digital signal processing applications to select and process different input signals. They are also used in control systems to select and route control signals.
- Memory addressing: Multiplexers are used to address memory locations in digital circuits. They enable multiple memory locations to be accessed using a single address line.
- Bus arbitration: Multiplexers are used in digital systems to arbitrate access to shared bus resources. They enable multiple devices to share a common bus while preventing conflicts and collisions.
- Error detection and correction: Multiplexers are used in error detection and correction systems to select and process data from redundant channels. They enable faulty data to be detected and corrected using error-correcting codes.
Here’s a summary of the key points about multiplexer in digital electronics:
- A multiplexer in digital electronics is a digital circuit that selects one of several input signals and transmits it to a single output line based on a control signal.
- Multiplexers simplify circuit design, reduce the number of required components, and enable fast switching and efficient use of resources.
- Multiplexer in digital electronics has several types, such as 2X1, 4X1, 8X1, and 16X1.
- Multiplexers are a critical component in modern digital electronics, offering cost-effectiveness, reliability, and versatility in a wide range of applications.
Here are some FAQs related to the multiplexer in digital electronics:
Q1: What is the difference between a multiplexer and a demultiplexer?
Ans: A multiplexer is a digital circuit that selects one of several input signals and transmits it to a single output line based on a control signal, while a demultiplexer performs the opposite function, selecting one of several output lines based on a control signal and transmitting a single input signal to that line.
Q2: Can multiplexers be used for analog signals as well?
Ans: Yes, multiplexers can be used for analog signals as well, but they require additional circuitry such as sample-and-hold circuits to handle continuous signals.
Q3: How many selection lines are required for an n:1 multiplexer?
Ans: An n:1 multiplexer requires log2(n) selection lines.
Q4: Can low-order multiplexers be used to create higher-order multiplexers?
Ans: Yes, low-order multiplexers can be used to create higher-order multiplexers. For example, an 8:1 multiplexer can be implemented by using two 4:1 multiplexers and one 2:1 multiplexer.
Q5: Can multiplexers be used for error detection and correction in digital circuits?
Ans: Yes, multiplexers can be used for error detection and correction in digital circuits by selecting and processing data from redundant channels. This enables faulty data to be detected and corrected using error-correcting codes.