Large signal-performance of active filters using amplifier pole

The effect of operational-amplifier nonlinearity on the performance of active-R, active-C, and “partial” active-R filters is investigated. Theoritical and experimental results show that the amplifier slew-rate limitation results in a characteristic which slants from the ideal flat response of the filter transfer functions.     

基于ADS的微带抽头式发夹型带通滤波器的设计

微带滤波器在通信系统中起着非常重要的作用,其性能的好坏直接影响着整个通信系统的性能。传统的设计滤波器的方法要通过理论进行大量的计算,计算过程繁杂。文章简要介绍了微带抽头式发夹型带通滤波器的设计理论以及如何通过ADS软件进行设计和优化仿真,并结合具体实例验证其可行性。     

Optimum tearing in large scale systems and minimum feedback cutsets of a digraph

In this paper we consider the problem of finding a minimum number of nonzero elements of a given nxn matrix on removal of which the resulting matrix can be permuted to an nxn lower triangular matrix using summetric permutations on the rows and columns of the matrix. The problem is related to finding a minimum feedback cutset for the digraph of the matrix. A topological method for finding a minimum feedback cutset for a given digraph is presented. Possible extensions to our work are indicated.     

Design of switched-capacitor filters using non-ideal op amps

A general synthesis procedure is given for the realization of switched-capacitor filters in the z-domain. The method uses biphased switches, capacitors and non-ideal op amps with finite gain-bandwidth product. The design includes at the outset the effects of the op amp gain-bandwidth product. Two examples are given which have been verified by a computer program.     

Design of fault diagnosis filters: A multi-objective approach

In this paper, fault detection and isolation (FDI) in linear uncertain dynamic systems is addressed. The main contributions consist of the formulation of the FDI problem as a filter-based multi-objective optimization problem and the study of the tools used for the solution. The design objectives are formulated in terms of H_∞, H_- and generalized H₂ performance specifications as well as regional constraints on filter poles. The problem is solved using linear matrix inequality (LMI) and generalized structured singular value (μ_g) techniques. Special design features are illustrated through a simulation example and experimental results from a controlled hydraulic process are provided to demonstrate the potential of the proposed procedure.     

The realization of grounded active RC multiport networks with a minimum number of capacitors

Applying a state-space technique and the reactance extraction principle in the realization of multiport network functions by means of grounded active RC networks containing grounded voltage-controlled voltage sources (VCVSs) and using a minimum number of grounded capacitors, a new theorem concerning the least upper bound on the number of grounded VCVSs sufficient for the realization is proved. The obtained expression for the least upper bound allows one to generate the least upper bound on the number of VCVSs sufficient to realize each of all possible different types of multiport network functions.The proof of the theorem is based upon the use of results concerning the number of VCVSs sufficient and, in general, necessary to realize an arbitrary real multiport network function by means of grounded active resistive multiport networks embedding grounded VCVSs, and on the results concerning the possibility of choosing a convenient equivalent minimal system realization.     

适用于海事卫星终端的体声波滤波器设计

近年来,国际海事卫星应用范围的扩展对终端设备的微型化与抗噪性提出了更高的要求,薄膜体声波滤波器成为人们关注的焦点。相对于传统滤波器,体声波滤波器具有更高的谐振频率和温度稳定性,更低的损耗和成本,同时可以实现芯片集成。本文介绍了FBAR体声波滤波器的工作原理与设计模型,在此基础上设计出了适用于BGAN下行频段的窄带滤波器。为实现材料参数的实时调整,本文采用Mason模型,通过改变串并联单元级数与面积比,最终设计出滤波器频带为1525~1559Mhz,带外抑制60dB,插损4.3dB。     

Global output feedback stabilization for a class of nonlinear systems with multiple uncertainties

This paper investigates the problem of global output feedback stabilization for a class of nonlinear systems with multiple uncertainties. A remarkable feature lies in that the system to be considered is not only involved dynamic and parametric uncertainties but also the measurement output affected by an uncertain continuous function, which leads to the obstacles in the constructions of a state observer and a controller. By revamping the double-domination approach with the skillful implantation of a dynamic gain scheme and nonnegative integral functions, a new design strategy is established by which a global output feedback stabilizer together with a novel state observer can be constructed successfully. The novelty of the presented design is attributed to a perspective in dealing with the output feedback stabilization undergone the unknown continuous (time-varying) output function and dynamic/parametric uncertainties. Finally, an illustrative example is provided to illustrate the effectiveness of the theoretical results.     

基于“因果关系反馈环”模型的公司和农户交易行为分析

运用新经济社会学的经验性研究方法--"因果关系反馈环"模型,分析了公司和农户之间的复杂交易关系.研究结果表明.由因果关系反馈形成的相互依赖,可以减轻公司和农户之间的"套牢"风险,这种相互依赖机制作为一种控制关系性风险的手段,是最小化交易成本的一种契约性制度安排.     

数字电视接收机中4阶CPPLL本振源的设计

在分析数字电视接收机前端4阶CPPLL基本工作原理的基础上,给出了一种实用的4阶CPPLL本振源的环路参数设计方法。用MATLAB编程PLL算法,然后采用ADS对系统稳定性及频域特性进行仿真,最后采用VC2003软件编写3阶无源环路滤波器设计软件,大大简化了4阶CPPLL设计,为类似的设计提供了良好的借鉴意义。     

Design of observer-based feedback control for time-delay systems with application to automotive powertrain control

A new approach for observer-based feedback control of time-delay systems is developed. Time-delays in systems lead to characteristic equations of infinite dimension, making the systems difficult to control with classical control methods. In this paper, a recently developed approach, based on the Lambert W function, is used to address this difficulty by designing an observer-based state feedback controller via assignment of eigenvalues. The designed observer provides estimation of the state, which converges asymptotically to the actual state, and is then used for state feedback control. The feedback controller and the observer take simple linear forms and, thus, are easy to implement when compared to nonlinear methods. This new approach is applied, for illustration, to the control of a diesel engine to achieve improvement in fuel efficiency and reduction in emissions. The simulation results show excellent closed-loop performance.     

一种C波段宽带二维扫描固态有源相控阵天线设计与实现

基于机载合成孔径雷达系统的具体应用,给出一种C波段宽带二维扫描固态有源相控阵天线的设计与实现方案.该天线辐射阵面采用双层矩形微带贴片,由宽带偶极子激励.通过增加金属隔墙和金属接地螺钉的加载来降低天线单元间互耦,实现了宽带二维相控扫描.测试结果表明,辐射单元阵中驻波带宽(VSWR＜ 1.6)达到800 MHz(相对带宽约15％).     

Design of 2-D stable analog and recursive digital filters using properties of the derivative of even or odd Parts of Hurwitz polynomials

In this paper, a method for the design of 2-D analog and recursive digital filters is presented. Starting from a structure in the analog domain, suitable even or odd parts of two-variable Hurwitz polynomials are generated. This enables 2-variable very strictly Hurwitz polynomials (VSHP) to be obtained,² thus avoiding non-essential singularities of the second kind. Thus it will ensure a stable 2-D recursive digital filter obtained by the use of bilinear transformations. Examples are given to illustrate the method.     

后发企业全球研发系统架构的设计规则——基于多案例比较的研发“走出去”过程研究

研发走出去已成为中国企业技术追赶的重要战略选择。建立面向全球的跨边界研发系统,需要协调好组织内外部的网络关系,合理设计其架构构建路径和方式。本文基于架构理论视角,通过探索性的多案例研究,分析在技术差距和制度差距的影响下,实施研发走出去战略的后发企业应当如何设计并建立组织架构和技术架构,从而获得全球研发系统构建与完善的最优解。根据案例研究结果,本文归纳了四种不同的技术架构和组织架构的模块性实现路径,深入探讨了目标选择、系统组建步骤和协调策略三个方面的全球研发系统构建的设计规则,为进行技术追赶的中国企业提供理论参考与实践启示。