A Radio Frequency power amplifier is an electronic device that converts a radio-frequency signal into a higher power signal. Typically, RF power amplifiers drive the antenna of a transmitter. RF amplifiers operate in different modes, called classes, class A, class AB, class B, class C  to help achieve different design goals. RF power amplifiers can be solid state amplifiers, usually modern ones,  or vacuum tube amplifiers, still used in very high-power amplifiers.