1. Definition of an RF power amplifier

An amplifier is a "device that increases the intensity of a phenomenon by borrowing energy from an external source". This is the Larousse definition. It should not be confused with the definition of a transmitter: "a device designed to produce radio signals and supply them to an antenna for radio communication (most of them include at least a pilot oscillator and modulator, power amplifiers and power supplies)".

However, this article deals with RF and microwave amplifiers. Oscillating power sources (MAGNETRON), low-noise amplifiers (LNA) for receivers, VLF and LF amplifiers, frequencies below 1 MHz and audio amplifiers are not covered.

The amplifier is a subassembly of the transmitter. The transmitter (figure 1 ) consists of a modulator that supplies a modulated...