What is a signal amplifier?

A signal amplifier is a circuit that uses electrical power to increase the amplitude of an incoming signal voltage or current signal, and output this higher amplitude version at its output terminals. The ideal signal amplifier creates an exact replica of the original signal that is larger but identical in every other way. In practice, a “perfect” amplifier is not possible, because no circuit can perfectly and proportionately scale up all aspects of a signal past a certain point.

Signal amplifiers are an essential component of thousands of devices, including landline and cellular telephone systems, music and public address systems, data acquisition (DAQ) systems, radio frequency transmitters, servo motor controllers, and countless more.

In data acquisition (DAQ) systems, signal amplifiers are needed to increase the amplitudes from sensors that output small signals, up to the level where they can be sent to an A/D converter (ADC) for digitization. The typical analoge-to-digital converter has an input aperture of ±5 V. Therefore, signals from thermocouples, shunts, strain gages, et al that are far lower than ±5V must be amplified significantly before they are sent to the ADC.

Types of signal amplifiers

There are several types of signal amplifiers, each capable of conditioning different signal types. Here is a list of some common signal amplifiers found in today‘s data acquisition systems:

Differential amplifiers

Isolated amplifiers

Voltage amplifiers: low voltage amplifier, high voltage amplifier, DC voltage amplifier, AC

voltage amplifier

Current amplifiers

Piezoelectric amplifiers

Charge amplifiers

Thermocouple amplifiers

Strain gauge amplifiers: bridge amplifier, full-bridge amplifier, half-bridge amplifier,

quarter-bridge amplifier)

Resistance amplifiers

LVDT amplifiers