In order to solve the contradiction between efficiency and EMC(Electro-Magnetic Compatibility) of the power amplifier thoroughly, and to reduce the power dissipation and environment pollution , a compact and applied power amplifier with high power and low EMI (Electro-Magnetic Interference) has been developed. The structure of analog servo power amplifier has been constructed and its principle and characteristic has been analyzed. At the same time system MATLAB simulation has been done; the feasibility and the reliability of the power amplifier control system has been confirmed theoretically.
The supply voltage for the output stage of the amplifier is varied with the input signal and the error between the power amplifier tube and the hoped value, so that the voltage applied to the active output transistor is held small and constant. The power dissipation of power amplifier is reduced and amplifier efficiency is raised appreciably. Based on the requirements to the performances of the analog servo power amplifier, resonant transformation network is used to produce high-frequency sine wave to supply silicon-controlled rectifier. To prevent environment pollution from Electro-magnetic interference and radio–frequency interference, the zero cross triggering is adopted to proceed rectified controllably.
Key words: Analog servo power amplifier; Servo-supply; Silicon-controlled rectifier; Zero-cross trigger