规范正交梯形结构对数域滤波器

提出了一种基于规范正交梯形网络信号流图模拟的对数域滤波器设计方法.能直接对给定的任意高阶传输函数进行综合.用该方法设计了1dB波纹三阶椭圆埘数域低通滤波器.Pspice仿真表明,所设计的滤波器实际频响特性几乎是理想的,而且具有电路结构简单、需要的元件数少、灵敏度低和最优的动态范围等特性.     

Simplified MOS switched capacitor ladder filter structures

A general technique for time-sharing amplifiers to reduce die area in switched capacitor ladder filters is described and illustrated with a fifth-order elliptic low-pass ladder filter requiring only three operational amplifiers. Techniques for synthesizing filters with maximum passband accuracy in the presence of parasitic capacitances are presented, and verified with two versions of the same fifth-order design integrated in a standard NMOS process. Passband accuracies of better than 0.1 dB have been achieved using only 0.3 pF unit-sized capacitors. The dynamic range is 75 dB.     

Auto-SC, an automated switched-capacitor ladder filter designprogram

The use of a switched-capacitor filter design program, Auto-SC, is discussed. The program can be used to design both single-ended and differential switched-capacitor filters by a number of different methods. Guidelines for designing switched-capacitor filters using Auto-SC are presented. The circuits designed by Auto-SC are in a format that is directly compatible with SWITCAP. A design example is included     

Bilinear switched-capacitor ladder filter with reduced number of amplifiers

A novel technique is described for the design of bilinear switched-capacitor ladder filters with a reduced number of amplifiers.     

New switched capacitor ladder filter with reduced number of amplifiers

A new simple method for designing switched capacitor ladder filters with a reduced number of amplifiers is described. The main building blocks in this design method are SC immittance convertors and SC current sources.     

The effects of matrix organization size and number of projectassignments on performance

Peters, Waterman, and a number of popular management authors have recently offered numerous criticisms of matrix structures. This investigation empirically tests two of these critical assertions in the areas of matrix organization size and number of project assignments. The findings based on a sample of 64 high-technology firms suggest that Peters' and Waterman's conclusions are incorrect     

A stray-insensitive single switched-capacitor ladder realization of an arbitrary order low-pass filter

A stray-insensitive biphase SC realization of an all-pole filter of any desired order is first obtained in the ladder form with all the SCs of equal value. These equal-valued SCs are then replaced by a single time-shared SC. Like any other time-multiplexed circuit, this circuit also requires an increased number of clock phases. Thus against an increase in the die area to generate a multiphase clock on the chip, there is a saving due to the reduction in the total capacitance. One such fifth-order low-pass filter is designed and tested with discrete components to verify its performance.     

改进的基于白化滤波器的降晰函数尺寸估计方法

给出了一种改进的降晰函数尺寸估计方法,它能为图像盲复原提供重要的先验信息,增强复原结果的可靠性.该算法首先由AR模型导出白化滤波器,然后对降质图像白化后的结果进行两种操作,以保证算法在低信噪比下的可行性:一是利用AR模型误差在边缘区域与平滑区域的差异,通过边缘提取与膨胀操作实现有效区域的快速提取;二是对有效区域通过平滑滤波进行噪声项的有效抑制.最后,对滤波后的有效区域进行相关值计算,依据取得最小值时的位移与降晰函数尺寸之间的关系估计降晰函数的尺寸.该方法经仿真实验验证:在低信噪比时,较改进前的方法能给出可靠的尺寸估计.     

A 3.6-MHz cutoff frequency CMOS elliptic low-pass switched-capacitor ladder filter for video communication

The high frequency (HF) behavior of the switched-capacitor (SC) LDI ladder filter is studied. This study shows that using low sampling frequency with respect to the cutoff frequency reduces the HF error due to the reduction in amplifier gain. Design techniques are also given for the HF SC filters, such as double-sampling scheme, a low sampling frequency with an exact synthesis algorithm, as well as a fast-settling folded-cascode amplifier. These techniques are applied to an experimental fifth-order elliptic SC filter fabricated in a 2-/spl mu/m CMOS technology. The experimental results show that a 3.6-MHz cutoff frequency is attained. All the capacitors are scaled down in order to reduce the setting time of the amplifiers. The active area of the filter is 0.9 mm/SUP 2/. The F/SUB sampling//F/SUB cutoff/ is only 5. The circuit operates from /spl plusmn/5 V and typically dissipates 80 mW when sampled at 18 MHz.     

计算共轴球面腔等价腔长时应注意的问题

本文通过相关例子,指出在计算共轴球面腔等价腔长时容易出现的错误,分析错误原因,并对易混淆的等价腔长、光学腔长及几何腔长三个概念进行了辨析.对等价腔长的概念进行了诠释,即共轴球面腔的等价腔长等于与该腔等效的G参数等价腔的空腔长度.这有助于学生对上述概念的理解和掌握.     

太赫兹MEMS滤波器性能影响因素

在太赫兹微电子机械系统(MEMS)滤波器的制作中,每一步工艺造成的误差都会对滤波器的性能造成影响,使滤波器达不到设计要求.为能够制作出满足指标的滤波器,对影响滤波器性能的尺寸、参数进行分析,且对这些参数进行仿真找到影响的规律;结合参数仿真与滤波器的测量进行整体分析,提出有效的解决方案,提高了太赫兹 MEMS滤波器的成品率和性能参数.     

点火电路中低通滤波器的接地对其性能的影响

火箭发动机的点火电路中常串联低通滤波器来消除高频干扰信号。在理想情况下,低通滤波器的插入损耗会随干扰信号频率的增大而增大,但在实际使用中,低通滤波器的接地回路中会有接地阻抗,导致干扰信号频率无限增大时,低通滤波器的插入损耗会减小;并且通过实际测试,接地阻抗越大,插入损耗会越小。为此在点火电路中应减小低通滤波器的接地阻抗,来有效防止高频干扰信号使发动机误点火。     

点火电路中低通滤波器的接地对其性能的影响

火箭发动机的点火电路中常串联低通滤波器来消除高频干扰信号。在理想情况下,低通滤波器的插入损耗会随干扰信号频率的增大而增大,但在实际使用中,低通滤波器的接地回路中会有接地阻抗,导致干扰信号频率无限增大时,低通滤波器的插入损耗会减小;并且通过实际测试,接地阻抗越大,插入损耗会越小。为此在点火电路中应减小低通滤波器的接地阻抗,来有效防止高频干扰信号使发动机误点火。     

Improved performance step impedance lowpass filter

Performances of the conventional Butterworth step impedance lowpass filters (LPF) are significantly improved by placing transmission zero either closer to the cut-off frequency (f_c) or away from it. It is achieved by using transverse resonance width of the capacitive line sections. We report method of designing transverse resonance type LPF (TR-LPF) for 5 to 11-pole filters. At f_c = 2.5 GHz, we obtained selectivity in the range 113.3–56.66 dB/GHz and 20–60 dB rejection BW in the range 9.61–7.29 GHz. The TR-LPF can suppress the stopband signal by 60 dB up to 5f_c. Insertion loss in passband is within 0.72 dB. Improved performance of TR-LPF can be designed for f_c up to 7.5 GHz.     

Initialization for improved IIR filter performance

A new method for initializing the memory registers of infinite impulse response (IIR) filters is introduced. In addition to providing improved performance as compared to other methods of initialization, this method is unique in that it makes no prior assumptions regarding the input-signal content. Therefore, the method applies equally well to a variety of IIR filter designs and applications. The method is best suited for signal processing applications in which `batch' processing of the data is used. However, sequential processing, can be accommodated when delays at the beginning of a processing segment can be tolerated     

A NEW APPROACH OF LADDER SIMULATION ACTIVE BANDPASS FILTER——USING COMPLEX SCALING AND NIC EMBEDDING

Here we present a new method of constructing ladder simulation filters using the complex scaling and negative immittance converter (NIC) embedding. This method saves the number of operational amplifiers, and thereby lowers the cost and power consumption. It also avoids floating elements, and is easy to adjust. It still acquires the merit of low sensitivity. The problem of error minimization and stability are also discussed.     

最易穿透粒径在高效超高效过滤器测试中的应用

本文介绍了什么是最易穿透粒径及其产生原因，并且介绍了高效过滤器和超高效过滤器的滤纸效率的测试，过滤器的渗漏测试，过滤器的全效率测试的测试过程及最易穿透粒径在各项测试中的应用。