What is a Signal Amplifier, and How Does It Work?

Data acquisition (DAQ) systems assist engineers in working with physical observations such as temperature, pressure, and current. Comprising of measurement devices, sensors, circuits, analog-digital-converters (ADC) computers, and software, DAQ systems are needed to get valuable information about industrial machinery, equipment, and devices through measured physical properties.

Physical parameters collected or measured as analog signals by sensors and other measuring tools must be converted into digital format to be stored, processed, and visualized by digital systems. When converting analog signals to digital format, an amplifier plays a key role in ensuring the integrity of the acquired signal so that accurate measurements can be achieved.

If you want to learn more about how amplifiers work, it’s essential to understand signal amplifiers and their role in DAQ systems and the key specifications that contribute to producing reliable measurements.

Function and Purpose of Signal Amplification

A signal amplifier is an electronic circuit that increases the magnitude or amplitude of an incoming current or voltage signal without changing its shape. It then outputs the magnified signal through designated terminals so other processes can take place on the higher amplitude version.

Signal amplification is an essential process in many devices and systems. Satellite communication, cellular phones, headphones and earphones, automotive systems, and data acquisition systems all make use of amplifiers.

In DAQ systems, signal amplifiers are required to increase the amplitudes from sensors that output low-level signals so they can be compatible with the analog-digital-converter unit. A typical ADC unit or device in a data acquisition system has an input aperture of ±5 V.

If the incoming analog signal does not fall within the supported range, the ADC might produce inaccurate results or even become damaged.

Therefore, signals from thermocouples, strain gauges, sensors, and other measurement devices must be amplified before being sent to the ADC of the data acquisition system.

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Types of Signal Amplifiers

There are different types of amplifiers. Which one to use in a DAQ system or device depends on factors such as signal type, operating frequency, and power output. Common amplifier types include:

Voltage amplifiers
Current amplifiers
Differential amplifiers
Piezoelectric amplifiers
Charge amplifiers
Isolated amplifiers
Thermocouple amplifiers
Strain gauge amplifiers
Resistance amplifiers
LVDT amplifiers

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Importance of Understanding Amplifier Specifications for Accurate Measurements

When in the market looking for a DAQ device such as a multi-input data logger, it's important that amplifier specifications and system configurations meet performance requirements. Precision-based measurement is especially required when monitoring and controlling temperature, pressure, flow, and other parameters of industrial processes and systems. Accurately collecting and analyzing temperature changes within a piece of equipment, for example, may reveal areas for urgent maintenance.

The best data acquisition system for a measurement job must not distort the original signal in any way. Below are some key system specifications for a DAQ device for accurate signal amplification and other conditioning processes.

Gain Accuracy: Gain is a measure of how much a signal is increased or amplified. Accuracy of gain compares the manufacturer’s expected gain out with the actual gain of the amplifier under specific operating conditions.
Gain Drift: Over-time changes in gain.
Gain Linearity: This measures the deviation in the amplifier’s output compared to the input.
Offset Accuracy: Offset is a constant value added to the input signal before amplifying the signal. Offset accuracy shows how close the manufacturer’s offset specification meets offset value in real-world applications.
Offset Drift: This refers to offset changes due to temperature or time.
Noise Floor: This refers to all signals aside from the main one being monitored.
Maximum Common-Mode Voltage: The maximum voltage that can simultaneously be applied to input terminals of a differential amplifier.
Input Ranges: The range of input voltages for which the ADC unit of a DAQ device is rated.
Bandwidth and “Alias-free” Bandwidth: The former refers to the ranges of frequencies a system can handle, while the latter is the maximum frequency that a DAQ device can sample without undersampling distortion (aliasing).
Sampling Rate: The number of signal samples captured per second.

An amplifier circuit or unit with the right configuration is essential for precision-based measurements.

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Applications and Benefits of Signal Amplifiers in DAQ Systems

During signal conditioning, amplifiers play a critical role in enhancing signal quality and enabling accurate data capture.

Applications of Signal Amplifiers

Sensor Signal Conditioning: Many sensors produce low-level signals, which are often too weak for the data acquisition system to digitize. Signal amplification boosts weak signals to a level suitable for the ADC part of a DAQ system.
Noise Reduction: Although the removal of unwanted noise is typically done at the filtering stage, amplifying a signal can help improve its signal-to-noise ratio (SNR), helping with signal clarity and accuracy.

Benefits of Signal Amplifiers in DAQ Systems

Apart from enhancing signal quality and accuracy, system integration is another major benefit to the workings of signal amplifiers. By being able to convert signal size to amplitudes the ADC can work with, amplifiers make it possible for DAQ devices like data loggers to work with different types of sensors and measurement devices.

KEYENCE offers DAQ solutions for precise measurement and control of industrial process parameters. Use DAQ devices and systems to achieve reliable measurements in key industrial and manufacturing processes.

Our multi-input DAQ NR-X device, for example, delivers consistent performance; it comes with a built-in amplifier unit as well as other technologies that reduce wiring work, improve signal-noise ratio, and ensure compatibility with different sensors and transducers.

The NR-X multi-input data logger can measure from different sensors, accepts up to eight measurement units, and supports up to 576 channels.

For more information on our data acquisition devices, contact us today.