Signal amplifiers operate on the principle of increasing the voltage, current, or power of a signal. The basic components of an amplifier include input and output terminals, a power supply, and active devices such as transistors or operational amplifiers. When a weak input signal is applied, the amplifier processes it and produces a stronger output signal.

The key parameters that define an amplifier's performance include gain, bandwidth, and noise figure. Gain refers to the ratio of output to input signal strength, while bandwidth indicates the range of frequencies the amplifier can effectively process. A low noise figure is desirable, as it indicates that the amplifier adds minimal noise to the signal. Understanding these parameters is crucial for selecting the right amplifier for specific applications.