低通开关电流Σ-Δ调制器的设计-电工理论与新技术专业论文.docxVIP

摘 摘 要 I I 摘 要 本文利用电流模技术，以开关电流（SI，Switched Curent）采样电路为核心， 研究和设计了音频应用的开关电流 ??????调制器。主要包括以下内容： (1) 选用了二阶单环负反馈作为调制器的基本结构，在分析和研究了开关电流 电路误差机理的基础上，使用 Matlab/Simulink 建立了第一代开关电流存储单元的 非理想模型，并利用该模型完成了 ??????调制器的系统级设计，通过模型仿真分析 了开关电流各类误差对 ??????调制器的影响。 (2) 为了消除 SI 存储单元的非理想误差，设计了一种全差分开关电流存储单 元。在大信号摆幅和低功耗的情况下，保证了线性要求，同时消除了时钟馈通（CFT， clock feedthrough）误差对电流的影响，大大提高了第一代 SI 存储单元的精度。 (3) 分别设计了 SI 积分器、电流比较器、电流模 DAC、电流镜、非交叠时钟、 带隙电压等电路，之后以差分电路结构实现二阶 ??????调制器的设计,该差分结构能 有效地降低失配对电路性能的影响，最后在 Cadence/Virtuoso 下完成整个电路芯 片版图。 本文设计的开关电流 ??????调制器采用 SMIC0.18μm 标准 CMOS 工艺实现，使用 1.8V 电源供电，过采样率为 125，采样频率为 5MHz，信号带宽为 20KHz。利用 spectre 仿真器进行仿真，结果显示最大信噪失真比接近 77.2dB,等效为 12.5 位分辨率,功 耗为 7.6mW,调制器版图面积为 220μm×300μm。 关键词：开关电流存储单元； ??????调制器；模数转换器；电流模 Ab Abstract I II Abstract Based on the special advantages of the current mode circuits, taking switch-current (SI) sampling circuit as the core,this paper is focused on the research and design of sigma-delta A/D modulator in audio application field with switched-current technology.The main contents of this paper include: This paper selects the second-order negative feedback(CIFB) as the basic structure of modulator, after detailed analysis of the error mechanism of the switch current circuit, established the nonideal model of the first generation switch-current memory cell in Matlab/Simulink,and builded the entire nonideal model of the second order lowpass modulator, through the simulation analysed how these errors manifest themselves in lowpass sigma-delta modulator. In order to eliminate the non-ideal errors of SI circuits,designed a full differantial SI memory cell,large signal swing and low power dissipation characteristics were realized without sacrificing linear,coupled differential outputs eliminate the clock feedthrough (CFT) error considerably,greatly improving the precision of the first generation SI memory cell. After complete SI integrator, comparator, current-mode DAC,current mirror, two phase non-overlaping clock generator,a full differantial