Principle: The high-frequency power amplifier is used in the final stage of the transmitter, the role is to amplify the high-frequency modulated wave signal to meet the requirements of the transmission power, and then through the antenna to radiate it into space, to ensure that the receiver in a certain area can receive a satisfactory signal level, and does not interfere with the communication of adjacent channels. High frequency power amplifier is an important component of transmission device in communication system. According to the width and narrowness of its working frequency band, it can be divided into narrowband high-frequency power amplifier and broadband high-frequency power amplifier. Narrowband high-frequency power amplifier usually takes a frequency selection circuit with frequency selection filtering as the output loop, so it is also called tuned power amplifier or 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 an untuned power amplifier.
High-frequency power amplifier is an energy conversion device, it converts the DC energy supplied by the power supply into high-frequency AC output in the \"low frequency electronic circuit\" course known, the amplifier can be divided into A, B, C three types of working state according to the different current conduction Angle. The current flow Angle of Class A amplifier is 360o, which is suitable for small signal and low power amplification. The current flow Angle of Class B amplifier is about 180o; The current flow Angle of Class C amplifiers is less than 180o. Both Class B and Class C are suitable for high-power work. The output power and efficiency of Class C working state are the highest of the three working states. High frequency power amplifiers mostly work in class C. However, the current waveform distortion of Class C amplifiers is too large, so it can not be used for low-frequency power amplification, and can only be used for resonant power amplification using a tuned loop as a load. Due to the filtering ability of the tuned circuit, the circuit current and voltage are still very close to the sinusoidal waveform, and the distortion is very small.
MCU is used to do the controller, composed of CPU, memory, input and output circuit, it determines the output signal according to the input signal and its own program, complete the corresponding control action.
Operational amplifier is a chip, with resistance and capacitance can complete a variety of addition, subtraction, multiplication and division operations, there are two inputs and an output, participate in the operation is current or voltage, operational amplifier can also do simple control, but the accuracy is not high. Never heard of an op amp test system.