D类功放中数字脉宽调制器的研究与设计
发布时间：2018-10-16 09:37
【摘要】：随着现代微电子技术的高速发展,数字音频愈发普及。若要对数字音源放大输出,对于传统的模拟放大器而言,需要在音源与放大器之间加入高精度的数模(D/A)转换器,提升了设计难度与成本。本文研究了一种利用全数字方式从数字音源信号直接到脉宽调制信号的转换方案,避免了高精度D/A转换器的引入,其过程如下：第一,本文对脉宽调制器的传统结构进行分析研究,讨论了传统脉宽调制器结构的缺点和不足,而后引出本文所设计的基于Sigma-delta调制器的新型脉宽调制器结构的解决方案。第二,通过研究与分析Sigma-delta调制器和噪声整形的基本理论,针对基本的Sigma-delta调制器结构进行改进,讨论了两种优化后的高阶Sigma-delta调制器结构。第三,通过MATLAB仿真设计了一款5阶7级Sigma-delta调制器。通过对噪声传输函数(NTF)的设计推导出调制器整体参数,而后仿真验证了调制器的稳定性及其输入幅值限制。结果表明：所设计两种方案的5阶7级Sigma-delta调制器对量化器输入信号幅值的限制都为1.8V,满足数字音频信号[-1,1]的幅度要求。对于加入零点优化的方案结构稍显复杂但是相比于仅优化极点分布的结构103.2dB的信噪比,能够达到更高的128dB信噪比。第四,为了给Sigma-delta调制器提供过采样的输入信号,本文基于对过采样技术与数字信号采样率转换技术的研究,通过三种不同方案设计了一款32倍增采样率转换器。其中对于CIC+半带滤波器和多相结构滤波器进行了FPGA实现。又对三种设计方案进行优劣比较。除原型FIR滤波器占用资源过大以外,另外两种方案都很好地完成了对数字音频信号的32倍增采样任务。本文实现了一款基于Sigma-delta调制的新型脉宽调制器的设计,为数字音源与数字D类功放直接实现无缝结合提供了解决方案。
[Abstract]:With the rapid development of modern microelectronics technology, digital audio is becoming more and more popular. In order to amplify the output of digital audio source, it is necessary to add a high precision D / A converter between the audio source and the amplifier for the traditional analog amplifier, which increases the design difficulty and cost. In this paper, we study a conversion scheme from digital sound source signal to pulse width modulation signal in all-digital mode, which avoids the introduction of high-precision D / A converter. The process is as follows: first, In this paper, the traditional structure of pulse width modulator is analyzed, and the shortcomings and shortcomings of the structure of traditional pulse width modulator are discussed. Then, the solution of a new type of pulse width modulator based on Sigma-delta modulator is introduced. Secondly, by studying and analyzing the basic theory of Sigma-delta modulator and noise shaping, the structure of the basic Sigma-delta modulator is improved, and two optimized high-order Sigma-delta modulator structures are discussed. Thirdly, a 5-order 7-stage Sigma-delta modulator is designed by MATLAB simulation. The overall parameters of the modulator are derived from the design of the noise transfer function (NTF), and the stability of the modulator and the limitation of the input amplitude are verified by simulation. The results show that the amplitude of the quantizer input signal is 1.8V restricted by the 5-order 7-stage Sigma-delta modulator, which satisfies the amplitude requirement of digital audio signal. For the scheme with zero optimization, the signal-to-noise ratio (SNR) of the proposed scheme is slightly more complex than that of 103.2dB, which only optimizes the pole distribution, and can achieve a higher SNR of 128dB. Fourthly, in order to provide the input signal of over-sampling for Sigma-delta modulator, based on the research of over-sampling technology and digital signal sampling rate conversion technology, a 32-fold sampling rate converter is designed through three different schemes. Among them, CIC half band filter and polyphase structure filter are implemented by FPGA. The advantages and disadvantages of the three design schemes are also compared. Except that the prototype FIR filter takes up too much resources, the other two schemes have accomplished the task of 32 times sampling of digital audio signal. In this paper, a novel pulse width modulator based on Sigma-delta modulation is designed, which provides a solution for the seamless combination of digital audio source and digital D power amplifier.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN787.2;TN722.75
本文编号：2273946
[Abstract]:With the rapid development of modern microelectronics technology, digital audio is becoming more and more popular. In order to amplify the output of digital audio source, it is necessary to add a high precision D / A converter between the audio source and the amplifier for the traditional analog amplifier, which increases the design difficulty and cost. In this paper, we study a conversion scheme from digital sound source signal to pulse width modulation signal in all-digital mode, which avoids the introduction of high-precision D / A converter. The process is as follows: first, In this paper, the traditional structure of pulse width modulator is analyzed, and the shortcomings and shortcomings of the structure of traditional pulse width modulator are discussed. Then, the solution of a new type of pulse width modulator based on Sigma-delta modulator is introduced. Secondly, by studying and analyzing the basic theory of Sigma-delta modulator and noise shaping, the structure of the basic Sigma-delta modulator is improved, and two optimized high-order Sigma-delta modulator structures are discussed. Thirdly, a 5-order 7-stage Sigma-delta modulator is designed by MATLAB simulation. The overall parameters of the modulator are derived from the design of the noise transfer function (NTF), and the stability of the modulator and the limitation of the input amplitude are verified by simulation. The results show that the amplitude of the quantizer input signal is 1.8V restricted by the 5-order 7-stage Sigma-delta modulator, which satisfies the amplitude requirement of digital audio signal. For the scheme with zero optimization, the signal-to-noise ratio (SNR) of the proposed scheme is slightly more complex than that of 103.2dB, which only optimizes the pole distribution, and can achieve a higher SNR of 128dB. Fourthly, in order to provide the input signal of over-sampling for Sigma-delta modulator, based on the research of over-sampling technology and digital signal sampling rate conversion technology, a 32-fold sampling rate converter is designed through three different schemes. Among them, CIC half band filter and polyphase structure filter are implemented by FPGA. The advantages and disadvantages of the three design schemes are also compared. Except that the prototype FIR filter takes up too much resources, the other two schemes have accomplished the task of 32 times sampling of digital audio signal. In this paper, a novel pulse width modulator based on Sigma-delta modulation is designed, which provides a solution for the seamless combination of digital audio source and digital D power amplifier.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN787.2;TN722.75
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