What Is a Multiplexer?
Multiplexers are switching devices that selectively route multiple input signals to a single output signal.
Multiplexers in digital circuits allow digital signals (bits) to pass through selectively, aggregating data into a single channel. Multiplexers in analog circuits, on the other hand, selectively pass analog signals (voltages or currents) through them, thus consolidating information from diverse signal sources into a single channel.
Thus, multiplexers can be a powerful tool for increasing the efficiency and sophistication of circuit design.
Applications of Multiplexers
Multiplexers are widely used in many digital and analog circuit design applications. Multiplexers, especially in digital ICs, are used in a variety of systems as the key component in digital circuits for selecting and switching data.
1. Data Selection Circuit
Multiplexers select one of multiple data inputs for output. For this reason, it is used as a data selector to select data to be transferred between the CPU and memory, etc. Since necessary data can be selected by addressing, multiplexers play an important function in data transfer circuits.
2. Analog-To-Digital Conversion Circuit
Multiplexers are used to select analog inputs in AD converters that convert analog inputs to digital data.
3. Communication Equipment
Multiplexers are used in wired and wireless communications equipment to combine multiple channels of data into a single transmission line. Multiplexers provide time-division multiplexing of data and improve transmission efficiency.
4. Measurement and Control Systems
Multiplexers are used to aggregate multiple channels of data from sensors and other devices. Multiplexers simplify the measurement system.
Principle of Multiplexers
Multiplexers are used for both digital and analog measurements, but the basic mechanism is the same.
1. Digital Multiplexers
Digital multiplexers are devices that selectively connect multiple digital inputs to a single digital output. It acts like a digital switch. There are multiple input lines, each with a corresponding control signal.
The control signal allows any input line to be connected to an output line. The selection of the input line is done by a control signal with a binary value (0 or 1). For example, in 2-input Multiplexers, a 1-bit control signal can be used to select which input is connected to the output. If the control signal is 0, the first input is selected; if the control signal is 1, the second input is selected.
2. Analog Multiplexers
Analog multiplexers select one of several analog inputs for analog output. The main internal components are an analog switch and an address decoder.
The address decoder takes a digital address as input that specifies the input channel to be selected. Based on this address signal, the address decoder generates a control signal for the corresponding analog switch. The analog switch uses this control signal to output the specified analog input in analog form.
Thus, analog multiplexers can also select any analog input by digital addressing. Because of their ability to switch analog signals at high speed, they are utilized in communication equipment.
How to Select Multiplexers
When selecting multiplexers, the following points should be considered
1. Intended Use
Multiplexers are available in analog, digital, and high-frequency types, depending on the application. It is important to select a type that matches the application and required characteristics.
2. Number of Inputs and Outputs
The number of inputs and outputs of multiplexers should be selected according to the scale of the system. The larger the number of inputs, the larger the system configuration.
3. Speed Performance
The switching speed of multiplexers may be especially important in some applications. For applications that require high-speed switching, check the speed characteristics.
4. Operating Frequency Range
For analog multiplexers, the frequency range over which they can operate determines their performance. It is necessary to confirm that the frequency range is compatible with the frequency band used.
5. Power Consumption
The power consumption of multiplexers is another aspect to check specifications. Selecting a low-power device can contribute to system power savings.