Development and design of wave SC filters

A direct z-domain simulation of LC ladder and unit-element filters by means of wave SC circuits is presented. the development of a wave SC circuit is achieved by interconnecting a limited number of basic SC building blocks. the derived circuits are fully parasitic-free, symmetric and can be optimally designed for dynamic range maximization and capacitance area minimization. the number of operational amplifiers in the simulated unit-element filters is essentially low in comparison to earlier presented parasitic-insensitive wave SC filters and to leap-frog-type SC filters. Four- and two-phase multiplexed simulated LCR filters can be developed. Bilinear s-z transformation applies for all the circuits; thus the design is exact and there is no requirement for a high clock frequency. Filters with transmission zeros can be developed. the simulated responses of various types of filters are in good agreement with the theory. Detailed examples of different designs are given.     

Design of wave-sc filters using building blocks

Besides switched-capacitor (SC) filters developed for high volume production, e.g. the PCM-codec lowpass filter, numerous low volume applications exist in the area of solid-state filtering. to open up this application field for SC filters, a novel wave-SC filter structure is presented. the filter design using this concept requires only moderate design and layout skills since only a limited library of highly modular building blocks is required. It is also suitable for analogue gate array applications. As will be shown, the wave equations which are known from the theory of wave digital filters can be realized using stray-insensitive SC integrators and SC amplifiers only. Exemplary designs of a lowpass, a highpass, and a bandpass filter will be carried out with the building blocks presented. the theoretical results are verified by measurements at the breadboarded lowpass filter.     

Sc filters based on scattering parameters

A systematic method for the simulation of LC ladders and unit-element filters by means of switched capacitor (SC) circuits is proposed. the method is based on the use of wave equivalents of various two-port subnetworks which are now realized by the same type of SC symmetric subcircuits. These subcircuits serve as the structural unit-blocks for realizing high-order circuits. Parasitic-free circuits of practical interest can be developed. Examples of high-order circuits are given. This wave method is simple in its concept and also in the circuit design. Through the alternative solutions which are described, the flexiblity of the method is demonstrated.     

Direct analysis and synthesis of multiphase switched-current networks using signal-flow graphs

A by-inspection analysis and synthesis method for multiphase switched-current (SI) circuits using signal-flow graph (SFG) techniques is presented. The SFG is derived on the transistor level and the method is primarily useful for the hand analysis and design of small and medium-size SI circuits (e.g. SI filters, decimators, interpolators). Tables of commonly used SI circuits, in which the corresponding SFGs and circuits are given, make the derivation easy and fast. From the SFGs, not only the overall discrete-time transfer function, but also those in-between individual switching phases, are obtainable. With the proposed method it is straightforward to include non-ideal effects, such as finite output resistance of MOS transistors, clock-feedthrough and settling error. The method is also a useful tool for the synthesis of new SI circuits. It is shown that every low-sensitivity switched-capacitor (SC) circuit can be mapped directly into a low-sensitivity SI circuit with a corresponding topology. Examples of transformed SC circuits are given and two new double sampling integrators are introduced. © 1998 John Wiley & Sons, Ltd.     

Low-sensitivity SC realization of brune and C-type reactance sections

The SC implementation of doubly terminated reactance reference filters containing Brune or C-type sections is presented. It is shown that the one-to-one correspondence between the elements of the reactance reference network and its simulated SC circuit is still maintained. Computer evaluations as well as experimental verifications have shown that the resulting structure is less sensitive with respect to parasitics. Illustrative examples are given.     

小功率电源SC-FDNR滤波器的设计

设计了一种小功率电源有源滤波器：利用一个单位缓冲器设计了对寄生电容不灵敏的开关电容 (SC) 频率相关负电阻(FDNR) 元件，利用该元件对椭园函数式LC低通滤波器进行SC模拟。为了获得电容最佳值，提出了一种简单的最优化方法；并采用寄生电阻预畸变与SC负电阻相结合的办法，设计的SC滤波器对寄生电容不灵敏，而且电路简单。本文用分立元件制作了一个五阶椭园低通SC-FDNR滤波器，实验结果表明该方法实用可行，效果明显。     

Canonic realization of wave digital filters involving unit elements

Recently, a method has been developed by means of which canonic wave digital filters can be derived from originally noncanonic ladder wave digital filters. This method applies only to wave digital filters which are derived from pure LC-ladder reference filters. In the paper, it is shown how noncanonic wave digital filters corresponding to reference filters containing unit elements can be transformed such that a canonic realization of these filters can be obtained as well.     

On a family of new two-op-amp switched-capacitor biquads for high-frequency applications

This paper presents three novel biquads derived by applying the concept of so-called basic elements for switched-capacitor (SC) circuits. These biquads are without continuous feedback and comprise two op-amps. They were derived assuming a transfer function denominator of the same form as the Fleischer-Laker type E circuit. It is shown that by a simple modification of the switching arrangement, i.e. by changing the type of the basic SC element, the effect of the amplifier finite gain on the performance of SC filters can be significantly reduced. the efficiency of this approach has been established by extensive simulation studies using the dedicated symbolic analysis program SCYMBAL. Design equations and comparison with already known biquads of this type are presented. Examples are provided to demonstrate that the proposed circuits require a low total capacitance while finite-gain effects are considerably reduced.     

高压直流输电系统直流滤波器的设计

直流滤波器是抑制高压直流输电(HVDC)直流侧谐波的最有效、最典型且应用最广泛的设施,其设计的优劣既牵涉到HVDC系统的运行性能和安全稳定性,又关系到整个系统总投资的高低。为深入研究直流滤波器的设计,首先总结了现有HVDC工程直流滤波器的配置现状,在分析直流滤波器电路结构和阻抗-频率特性的基础上,忽略电阻的影响,根据调谐点滤波器阻抗Z=0,推导了双调谐滤波器和三调谐滤波器设计的精确公式,提出了详细的参数设计方法,而公式有多组解,选取最大的串联谐振频率rω1那一组解,此时滤波器阻抗-频率特性在谐振点附近的曲线比较平坦,滤波效果最好。然后以HVDC实际工程直流滤波器参数进行验证,结果表明所提出的公式完全正确,可为直流滤波器的参数设计提供工程指导。最后以满足等效干扰电流为基本要求,对某HVDC工程的直流滤波器进行了实例设计。     

Scaling techniques for switched-capacitor filters employing voltage inverter switches

Some realizations of scaling elements in cascade connection with unit elements and gyro-elements will be described. It will be shown that the voltage distribution inside the filter and the spread of capacitor values can be optimized in two steps using two independent parameters for each scaling element. the influence of these scaling elements is such that the very low sensitivity of the attenuation characteristic with respect to element variations is fully retained despite the fact that according to the usual definition the losslessness of the reference filter is not preserved. the SC circuits described in this paper are insensitive to ‘bottom plate’ parasitic capacitances. Top plate parasitics correspond largely to element variations in the reference filter so that also their influence is strongly reduced. A numerical example of a 14th-order unit element bandpass filter is given.     

Technique and Calculation Results of Currents and Voltages in the Circuits of the Measuring Element of the Protection Device of the Transmission Line Based on the Control of Transient Processes

The specifics of generation of the signals of current and voltage in the circuits of a directional element of wave relay protection during short circuit (SC) in overhead power transmission lines are considered. The computing method of transient processes in the protection circuits, including frequency filters, that attenuate the parameters of currents and voltages of the mode taking into account the higher harmonic components and probable deviations of the frequency of transmission line from the rated value is presented. It is revealed that it is advisable to implement the measuring circuits of the directional elements of wave relay protection with the three-section filter attenuating the frequencies from 45 to 55 Hz and the low pass filter with cutoff frequency that does not exceed 1 kHz.     

Time domain analysis and design of multirate wave digital filters

A generalized time domain approach is described for the analysis and design of wave digital filters capable of performing sampling rate alterations whether integer or non-integer. It is based on sequential computation of the filter's system response; then this discrete response is reduced to a rational function form. the proposed approach is characterized by its simplicity as well as its ability to analyse and design multistage, multirate wave digital structures. Illustrative examples are also given.     

Interpolation filters for 2-D hexagonally sampled signals

This paper deals with the design of interpolation filters for 2-D hexagonally sampled signals using multidimensional antimetric wave digital filters. Theoretically there are two essential schemes for the interpolation of hexagonally sampled signals, i.e. interpolations by factor 3 and by factor 4. We show that by exploiting some symmetry properties of the amplitude response, multidimensional antimetric filters are suitable for the design of interpolation filters in both cases. In particular, very efficient design can be obtained for the case of interpolation by factor 4, for which very low hardware cost is required for achieving satisfactory amplitude responses. The paper also compares the behaviours of the designed interpolation filters with those of circularly symmetric filters realized by cascading some antimetric filters. © 1997 John Wiley & Sons, Ltd.     

Design of switched-capacitor elements with voltage inverter switches for the simulation of FDNR Reference Structures

A number of new elements for switched-capacitor filters based on voltage inverter switches will be described. the new circuits simulate elements which are obtained from the normally used ones by FDNR transformation. They are insensitive to bottom plate parasitics and the influence of the to plate parasitics can be reduced. No matching is required between any capacitors in the SC circuit, so that the same low sensitivity to element variation holds as for the reference structure. These new elements allow realization of some further filter structures.     

新型开环耦合谐振滤波器的设计与应用

为了满足日新月异的无线通信对小型化带通滤波器的要求,针对传统类型滤波器存在线性度、矩形系数、插入损耗、体积等方面的问题,笔者介绍了一种通过在微带开环谐振滤波器中引入交叉耦合,产生一对传输极点,从而提高滤波器选择性的滤波器设计方法,并讨论了这种滤波器的综合方法和实现流程。实际设计了一个六阶开环谐振滤波器,并给出了全波仿真结果。分析和仿真都表明这种滤波器具有体积紧凑、选择性高的优点。     

Design criterion for high‐speed low‐power SC circuits

The settling behavior of switched‐capacitor (SC) circuits is investigated in this paper. The analysis is performed for typical SC circuits employing two‐stage Miller‐compensated operational amplifiers (op‐amps). It aims to evaluate the real effectiveness of the conventional design approach for the optimization of op‐amp settling performances. It is demonstrated that the classical strategy is quite inaccurate in typical situations in which the load capacitance to be driven by the SC circuit is small. The presented study allows a new settling optimization strategy based on an advanced circuit model to be defined. As shown by design examples in a commercial 0.35‐ µm CMOS technology, the proposed approach guarantees a significant settling time reduction with respect to the existing settling optimization strategy, especially in the presence of small capacitive loads to be driven by the SC circuit. Copyright © 2010 John Wiley & Sons, Ltd.     

改进滞环比较器的永磁同步电动机直接转矩控制

在研究了永磁同步电动机直接转矩控制基本原理的基础上，分析了直接转矩控制方案的特点及不足。理论分析结合仿真均表明。对称的磁链滞环调节使转矩波动较大且超出转矩滞环的宽度，将磁链滞环的宽度设得很窄时，可以减小这种波动，但逆变器的开关频率随之增大。本文在分析这种波动产生原因的基础上，提出对滞环比较器进行不对称上下限的设置以抑制转矩较大的波动和降低逆变器的开关频率。仿真结果表明，该方法使得转矩波动限制在要求内，逆变器的开关频率降低。得到了较好的转矩控制效果。     

三调谐电力滤波器的研究

在分析单调谐滤波器和双调谐滤波器特性的基础上，提出了一种等效于三组单调谐滤波器的三调谐滤波器，该滤波器由3个电感和3个电容组成；分析了该滤波器的阻抗特性，给出了参数的计算方法, 通过额定电压、调谐频率、并联谐振频率和补偿容量等已知数据计算出电感和电容元件的参数；并针对一110kV实际电网，完成三调谐滤波器设计计算、仿真分析和试验测试。结果表明该滤波器有良好的滤波性能，可以同时滤除三种不同频率的谐波，频率误差不超过2Hz，性能优于三组单调谐滤波器，具有基波损耗低、占地小、投资省、只有一个电抗器接受冲击电压、只需要一个开关等优点，适合在电力系统推广应用。     

Canonic realization of ladder wave digital filters

Wave digital filters which are derived by previously known methods from LC ladder reference filters having attenuation poles at frequencies other than zero or infinity, although being canonic in number of multipliers, are not canonic in number of delays. A simple procedure is given by means of which a canonic realization can always be derived from an originally noncanonic ladder wave digital low-pass, high-pass, or band-pass filter. This procedure does not affect the values of the multiplier coefficients.     

基于LABVIEW的虚拟滤波器的设计与实现

虚拟实验作为传统实验的一个有益的补充,已成为当前研究的热点之一,虚拟滤波器就是应用范围比较广泛的一种虚拟仪器。针对建立虚拟实验平台的需求,设计了基于LABVIEW的虚拟滤波器,该虚拟滤波器是通过数据采集卡来采集外部信号,通过图形化语言编程来实现仪器的滤波、分析及显示功能。该虚拟滤波器主要信号采集、重置滤波器、幅值和电压测量、频域分析、时域分析及存储与显示等模块组成,与传统仪器相比有许多优点,如可以随时记录分析过程和结果、开发时间短、成本低廉,可以根据需要灵活的进行功能扩展等。实验证明,该虚拟滤波器滤波性能良好、运行快速、结果可靠,能够达到实验要求。