What Is a Multiplexer IC?
A multiplexer IC is an IC that outputs multiple signals as a single signal.
It is also called a MUX, multiplexer or multiplexing device. In digital circuits, it is represented by a rectangular or trapezoidal block notation with a large ratio of length to width, with inputs on the long side and outputs on the short side. Several multiplexer ICs can be combined to increase the number of inputs.
In the field of communications, multiplexers are often used to transmit data from multiple signals by combining them into a single composite wave using switches and filters. On the receiving side, a demultiplexer corresponding to the multiplexer is required to break up the signal of the composite wave into multiple signals so that the signals can be read.
A multiplexer and demultiplexer combined into a single unit is sometimes called a multiplexer, and is used in different situations depending on the case.
Uses of Multiplexer ICs
Multiplexer ICs are often used in the field of mobile radio communications, computer circuits, and signal synthesis in analog circuits. In the field of communications, applications include satellite signal transmitters, Wi-Fi routers, remote-controlled robots, and drone operations.
When selecting a multiplexer IC, it is necessary to consider various specification, such as size, supported signals, voltage, and package options.
Principle of Multiplexer ICs
The principle of multiplexer ICs is that they are designed and developed so that output signals based on the desired logic can be formed from a number of input signals according to the specifications of each IC, usually using a combination of digital circuits or analog switch circuits. Based on the digital logic design and analog circuit design, the wiring layout of CMOS and other transistors, resistors, capacitors, and other components that make up the necessary circuits inside the IC are laid out.
A normal multiplexer IC consists of several input pins and one output pin. If there are N inputs, the signal can be processed as one output to the power of 2N signals. The mechanism is that there are as many switches as there are signal inputs, and signals are synthesized by combining 0 and 1 signals.
Taking an 8-input multiplexer as an example, it has 8 data inputs and 3 signal selection switches. This can represent 8 input data in 3-digit binary numbers. Some multiplexer ICs include IC chips with capacitor and coil functions to provide additional protection against power off, overvoltage, and short circuits. Products are also available that incorporate optimum amplifiers and filters to handle high frequencies and transmit signals with high precision.
Other Information on Multiplexer ICs
1. Multiplexer Configuration Circuit (Digital)
When a multiplexer IC is composed of digital circuits, a “combinational circuit” is used. The components of a combinational circuit include AND, NOT, and OR circuits.
Flip-flop circuits, which are often used in digital circuits, have a data retention function and are usually not used in multiplexer circuits, but are components of sequential circuits.
2. Example of Multiplexer IC Configuration (Analog)
Multiplexer ICs are often used in analog circuits, especially for communication applications, such as antenna switches and frequency band switching filter circuits that handle the signal switching function for transmission and reception around antennas.
In recent mobile communication applications, SOI-CMOS switches are used as IC components and equipped with serial interface functions based on digital circuits for transmission and reception.