This is one the main characteristics to determine when designing or choosing an amplifier. This is a measure of the increase (or decrease in case of negative gain) the amplitude of the input signal.
Representation:
There are a few different ways to represent amplifier gain. One of the more common way among beginners and hobbyists, specially for DC or small signals, is to describe gain as the ratio of input vs output amplitude:
Gain = Vout/Vin, Where both input and output are either voltage or current (amperage).
Another way to represent amplifier gain is using a logarithmic decibel scale (dB). This representation is calculated using the ratio of input/output powers using the formula:
Gain = 10log(Pout/Pin)
Utility of gain:
There are countless applications and uses for amplifiers, since in the electronics world most signals we get from sensors or transmission lines is very small. There are also other times when not the amplitude of the signal is required but its power to transform into useful work, like when powering a motor, transmitting a radio signal and displaying an image on a screen.
How to calculate:
The specifics of how much gain can an amplifier have depend heavily on the components or circuits used, as well as the topology (configuration) of the amplifier. You can have a better understanding of the formulas used for each component and configuration by going to the specific page.
