[Aigtek Popular Science] What is a preamplifier? How to distinguish it from a power amplifier?

Hello everyone~ This is Aigtek science time. I believe you are all familiar with power amplifiers. What is a preamplifier that looks very similar to a power amplifier? What are the differences between it and a power amplifier? Today we will take you to learn more about it.

A preamplifier is a circuit or electronic device placed between the signal source and the amplifier stage. It is designed to receive weak voltage signals from the signal source. It can convert weak electrical signals into signals with strong enough output signals and strong enough noise tolerance for further processing, so that the signal is not distorted.

The preamplifier amplifies the useful signal and also amplifies the noise. A low-noise preamplifier is a preamplifier that minimizes the noise figure of the circuit. For weak signal detection instruments or equipment, the preamplifier is one of the main components that introduces noise.

Because the specific requirements are different for different types of measurements. When amplifying sensor signals, it is often necessary to select an appropriate preamplifier according to the sensor type.

Temperature sensors generally have voltage output, so a voltage input type preamplifier should be used. Photodiodes used for light detection generally have current output, so a current input type preamplifier should be used.

In addition, the requirements for the preamplifier output signal will also change depending on the purpose of use. For example, high-speed response functions are required for image processing, and low-noise characteristics are required for spectral measurement of materials such as semiconductors.

Simply put, the preamplifier amplifies small signals at the millivolt (mV), microvolt (µV), and nanovolt (nV) level to the millivolt or volt level. It can be monitored on testing instruments such as oscilloscopes without output power to drive the load.

Aigtek preamplifier