High frequency power amplifier is a kind of amplifier circuit that can convert the energy of DC power supply into high frequency signal energy, its main function is to amplify the high frequency signal power, with relatively high output power and efficiency.
The basic requirements for it are frequency selection, large output power, small own loss, high efficiency, so in order to improve efficiency, generally choose to work under class B or C, but at this time the collector current is a cosine pulse, so the resonant circuit must be used to load, in order to get the required frequency of sine high frequency signal.