Single OpAmp Higher-Order Filters in Sigma-Delta Modulators

该项目的目的是分析，仿真和误差校正的Σ-Δ调制器（SDM）与高阶环路滤波器实现了一个较小的数量-在极端情况下，一个单一的运算放大器。这种技术是用于离散滤波器几十年前，以节省有源元件。在SDM中，它已经使用了好几年，运算放大器数量的纯粹减少被认为是优点;但这应该更普遍和更详细地提出质疑：在SDM环路滤波器中，所有运算放大器对动态范围、线性度、噪声、速度等等，使得用单个运算放大器实现高阶滤波器迅速地导致对单个放大器组件的极高要求，这根本不能实现或仅需要很大的成本。另外，SDM现在经常用于无线接收机的连续时间实现，其中带内和带外的信号传递函数是至关重要的。信号传递函数的修改既可以在架构级实现，也可以通过在SDM环路中添加附加（数字）滤波器来实现。这种可能性不再是在所述高阶滤波器只有一个或几个运算放大器。因此，建议的项目将致力于两个SDM与高阶环路滤波器实现一个或几个运算放大器的一般分析。灵敏度分析有关放大器的非理想性，这些非理想滤波器的建模，可能的补偿方案的非理想滤波器在建筑水平，无论是通过分析方法和使用启发式优化进行了研究。为了最终“证明”所找到的方法相对于目标受众的工作，电路设计师，也是一个现有的电路实现的宽带SDM与经典的环路滤波器架构将被修改-最大限度地重用现有的组件-到一个单一的放大器结构;电路将被制造和测试的概念证明。

The aim of the proposed project is the analysis, simulation, and error correction in Sigma Delta modulators (SDM) with higher-order loopfilters realized by a smaller number of - in the extreme case of a single - operational amplifier.This technique was used in discrete filters decades ago to save active components. In SDM it gas been used for several years now, and the pure reduction of the number of operational amplifiers is stated as the advantage; but this should be questioned more generally and in more detail: in a loop filter of a SDM all operational amplifiers have completely different requirements on dynamic range, linearity, noise, speed, etc. so that the implementation of a higher-order filter with a single operational amplifier rapidly leads to extremely high demands on the single amplifier component which cannot at all be realized or only at great expense.In addition, SDM are nowadays often used in continuous-time implementation for wireless receivers, in which the signal transfer function within and outside the inband is crucial. A modification of the signal transfer function can be achieved both at the architectural level, as well as by adding additional (digital) filters in the SDM loop. This possibility is no longer available in the said higher order filters with only one or a few operational amplifiers.Therefore, the proposed project will be devoted to both the general analysis of SDM with higher order loop filters implemented with one or a few operational amplifiers. Sensitivity analysis concerning amplifier non-idealities, modeling of these non-ideal filters, possible compensation schemes for the non-ideal filters at the architectural level, both by analytical methods and using heuristic optimization are studied. For a final "proof" of the found methods with respect to the target audience of the work, circuit designers, also an existing circuit implementation of a broadband SDM with a classic loopfilter architecture will be modified - maximally reusing the existing components - into a single amplifier structure; the circuit will be manufactured and tested as proof of concept.