用于音频编码的sigma-delta调制器研究与CMOS设计

发布时间：2018-02-08 12:03

本文关键词： sigma-delta调制器开关电容积分器带隙基准信噪比　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：Sigma-Delta A/D转换器因其具有高精度、高线性度、易于集成、价格低廉且对采样信号有抗混叠作用等优点,在音频数字信号处理系统中得到广泛采用。本文在分析了Sigma-Delta调制器基本理论的基础上,对不同的调制器结构进行了对比,掌握了调制器结构、阶数和过采样比与信噪比的关系后,预设定了sigma-delta调制器系统指标。并运用了MATLAB软件中的SIMULINK工具对二阶,三阶单环Sigma-Delta调制器进行行为级建模仿真,验证调制器系统电路的可行性和正确性后,设计了一款处理音频信号的Sigma-Delta调制器。该调制器采用二阶单环结构实现,包括开关电容积分器、比较器、一位数模转换器、带隙基准源、非交叠时钟等电路,为了提高供电电源的稳定度,带隙基准电路进行了曲率补偿设计,该基准电路基于MOS管亚阈值电压的指数特性,去补偿PNP型晶体管发射极电压的高阶温度项,进而获得超低温漂系数的基准源。基于SMIC 0.35um CMOS工艺,进行整体电路仿真,对仿真结果进行频谱分析表明:在3.3V的电源电压,过采样比为64的条件下,本论文所设计的Sigma-Delta调制器的有效位数大于12位,调制器的性能指标达到设计要求。
[Abstract]:The Sigma-Delta A / D converter has the advantages of high precision, high linearity, easy integration, low cost and anti-aliasing effect on the sampling signal. It is widely used in audio digital signal processing system. On the basis of analyzing the basic theory of Sigma-Delta modulator, the different modulator structures are compared, and the modulator structure is mastered. After the relation between order and over sampling ratio and signal-to-noise ratio (SNR), the system index of sigma-delta modulator is preset. The second order and third order single loop Sigma-Delta modulator is modeled and simulated by using SIMULINK tool of MATLAB software. After verifying the feasibility and correctness of the modulator system circuit, a Sigma-Delta modulator for audio signal processing is designed. The modulator is implemented with a second-order single-loop structure, including a switched capacitor integrator, a comparator and a digital-to-analog converter. In order to improve the stability of power supply, the bandgap reference circuit is designed by curvature compensation, which is based on the exponential characteristic of sub-threshold voltage of MOS transistor. In order to compensate the higher-order temperature term of emitter voltage of PNP transistor, the reference source of ultra-low temperature drift coefficient is obtained. Based on SMIC 0.35um CMOS process, the whole circuit simulation is carried out. The spectrum analysis of the simulation results shows that the power supply voltage is 3.3 V, When the oversampling ratio is 64, the effective bit number of the Sigma-Delta modulator designed in this paper is more than 12 bits, and the performance of the modulator meets the design requirements.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN761

【相似文献】