Principle: The high-frequency power amplifier is used in the final stage of the transmitter. Its role is to amplify the high-frequency modulated signal to meet the transmission power requirement, and then radiate it to space through the antenna to ensure reception in a certain area. The receiver can receive a satisfactory signal level and does not interfere with the communication of adjacent channels.
A high-frequency power amplifier is an important component of a transmitting device in a communication system. According to the width of its operating frequency band, it is divided into two types: narrow-band high-frequency power amplifier and wide-band high-frequency power amplifier. Narrow-band high-frequency power amplifiers usually use a frequency-selection circuit with a frequency-selection filtering function as the output circuit. Resonant power amplifier; the output circuit of a broadband high-frequency power amplifier is a transmission line transformer or other broadband matching circuit, so it is also called a non-tuned power amplifier.
A high-frequency power amplifier is an energy conversion device that converts DC energy supplied by a power source into a high-frequency AC output. It is known in the course of "low-frequency electronic circuits". The amplifier can be divided into A according to the current conduction angle. , B, C working status. Class A amplifier current flow angle is 360o, suitable for small signal low power amplification. Class B amplifier current flow angle is approximately 180o; Class C amplifier current flow angle is less than 180o. Both Class B and Class C are suitable for high-power work. The output power and efficiency of Class C are the highest of the three working states. Most high-frequency power amplifiers work in Class C. However, the current waveform distortion of the Class C amplifier is too large, so it cannot be used for low-frequency power amplification, and can only be used for resonance power amplification using a tuning loop as a load. Because the tuning loop has filtering capabilities, the loop current and voltage are still very close to the sinusoidal waveform, and the distortion is very small.