| With the rapid development of consumer electronic products, low power dissipation and high efficiency has become the pursuit of all portable electronic products. With low power dissipation and high efficiency, Class-D power amplifier extends the using time of audio portable electronic products, and complies with the trend of the electronics industry. The efficiency of Class-D power amplifier is higher than that of traditional linear power amplifier a lot, but EMI and distortion have plagued the design of Class-D power amplifier. Therefore, the study of ultra-low EMI filter-free Class-D audio power amplifier in this thesis has a certain theoretical and practical significance.An ultra-low EMI, filter-free Class-D audio power amplifier chip is designed in this thesis, and the operating voltage range is2.4V-5.5V. With the dual-loop negative feedback and maximum conduction time control technology based on the three-state output modulation, chip can effectively reduce the nonlinear distortion and noise of power supply. With the carrier signal of the PWM modulation by using spread spectrum technology, chip can significantly improve EMI problem.The main content of this thesis as follows:First of all, this thesis described several traditional linear power amplifier, and expounded the principle of Class-D power amplifier, gave the important parameters of measuring Class-D power amplifier at the same time; Second, this thesis analyzed the system’s loop in detail, and expounded the basic theory of spread spectrum. With the simulated and validated by MATLAB, this thesis optimized various parameters of the system loop, and gave the standard of selecting spread parameter; Third, the oscillator module is designed and simulated. At the same time, the function of the whole chip was simulated and validated and result of FFT analysis was given. Finally, this thesis gave a summary, and pointed out that the future research directions in Class-D audio power amplifier for author. |
PDF Full Text Request