| Digital audio power amplifier use and analog amplifier device different amplification technology, make amplifiers pipe work in the class D switch state, so also known as the class D power amplifier, with its small volume, low power consumption, high efficiency advantages gradually become the mainstream of the sound field, in the future portable and high-power stereo in the field of electronic equipment development foreground is very wide, so to digital audio power amplifier research has the very important meaning.Class D power amplifier device energy efficiency is very high, theoretically can reach100%, but as a result of class D amplifier belongs to nonlinear devices, pulse width modulator, switch amplifier and the low pass filter and other links will make the application of actual output efficiency is low, and can lead to different degree of nonlinear distortion, this also is before class D power amplifier device use limited important reason. Relevant departments at home and abroad in the research of digital power amplifier device efficiency generally is about85%, more than200w high power amplifier device research and development’s achievements more small. So as to further enhance the digital power amplifier efficiency and improve the degree of distortion, frequency response, signal-to-noise ratio these influences the quality of the sound quality index is very important.Based on the traditional class D power amplifier device based on the analysis of the research, the part of the circuit structure were improved design, design a kind of more efficient, less distortion of class D audio power amplifier. The improved design scheme mainly include:1. The two way back width modulation modes into class D power amplifier device of the pulse width modulation design, reduced the static current and reduce the power consumption;2. Pulse width modulation using NBDD sampling method, may improve the signal-to-noise ratio and decrease the degree of distortion;3. in the switch amplifier introduced into the Dead band Time (Dead-Time) control circuit, which can reduce the power amplifier pipe in collusion with loss and Cds loss and improve the efficiency of the amplifier;4. Introducing negative feedback circuit, which can reduce the system to produce a nonlinear distortion and noise.This paper according to this scheme for improving the design of digital power amplifier, power output reached1000w (half bridge) or2000w (full bridge), distortion (THD) is less than0.05%, the signal-to-noise ratio is more than110db, the efficiency is above90%, and thus realizes the audio power amplifier for high efficiency and high fidelity aspects of the basic requirements. |
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