An amplifier is an electronic device that increases the strength of a signal. There are many different types of amplifiers, including RF amplifiers, audio amplifiers, and power amplifiers. Special purpose amplifiers are a type of amplifier that is designed for a specific application or function. These amplifiers may be designed to amplify a specific type of signal, or to provide a specific amount of gain. Some examples of special purpose amplifiers include RF amplifiers for use in radio and telecommunications systems, and low-noise amplifiers for use in precision instrumentation and scientific measurement systems.