On the practical realization of higher-order filters with fractional stepping

We propose the use of a compact integer-order transfer function approximation of the fractional-order Laplacian operator s^α to realize fractional-step filters. Lowpass and bandpass filters of orders (n+α) and 2(n+α), where n is an integer and 0<α<1, can, respectively, be designed. A 5th-order lowpass filter with fractional steps from 0.1 to 0.9 (i.e. 5.1→5.9) is given as an example with its characteristics compared to 5th- and 6th-order Butterworth filters. Spice simulations and experimental results are shown.     

Pascal's triangle: An origin of Daubechies polynomials and an analytic expression for associated filter coefficients

After showing that Daubechies polynomial coefficients can be simply obtained from Pascal's triangle by some elementary additions, we propose a derivation of the spectral factorization by using the elementary symmetric functions. This derivation leads us to present an analytic expression, able to compute Daubechies wavelet filter coefficients from the roots of the associated Daubechies polynomial. Thus, these coefficients are directly obtained and without recurrence. At last, we measure the quality of the coefficient sets generated by this expression and we compare it with two well-known methods.     

窄带多通道滤光片的设计与制备

介绍了三种获得窄带多通道滤光片的方法。第一种方法是具有缺陷的多异质结结构,该结构能够展宽光子晶体的禁带同时实现多通道效应。第二种方法是多通道导模共振布儒斯特滤光片,此类滤光片可以采用单层膜结构来实现多通道效应,也可以采用具有相等折射率的双层膜结构来实现多通道效应。第三种方法是组合刻蚀法制备窄带滤光片列阵。该方法不仅可以制作单腔窄带滤光片列阵,还可以制作双腔窄带滤光片列阵。窄带多通道滤光片在光学领域中具有一定的应用前景。     

The effects of CCII non-idealities on voltage-mode active filters

In active filters, the performance of the active element plays an important role in the overall performance of the filter, besides the filter configuration itself. In this paper, we will investigate the effects of current conveyor non-idealities on a certain class of filters which consists of four current conveyors and seven nodes, and derive analytical expressions for the filter parameter deviations in terms of non-ideality terms. The results obtained apply to all filters under this class which are considerable in number. This will enable us to determine the requirements for the current conveyor non-ideality terms in order to obtain a specified filter performance. A comparable demonstration of the filter transfer functions for two example current conveyor circuits will be given. Simulations including three types of filters, namely, the bandpass, lowpass and highpass filters, confirm the analytical expressions obtained.     

一类最佳数据压缩FIR滤波器与Daubechies 小波

提出了一种设计数据压缩FIR滤波器的新方法．该方法在不引入信息失真的前提下以最有效分解原信号为目的设计滤波器．由此设计的滤波器可以实现数据基于压缩目的的最优分解,能够最大可能地提取信号中的有用信息同时去除冗余信息．该分解过程与具有一定正则性的Daubechies小波的离散小波变换十分相似,该滤波器也和Daubechies小波分解滤波器完全相同,其原因是Daubechies在构造小波时引入的余项应为零．     

Analysis of two-dimensional center weighted median filters

Center weighted median (CWM) filters, which have been recognized as detail preserving filters, are an important and the simplest subclass of weighted median (WM) filters. In this paper, we analyze the root signals of two-dimensional (2-D) CWM filters. In particular, we derive the required form for a signal to be a root of a 2-D CWM filter. The required form of signals to be roots is then used to evaluate the detail preserving properties of 2-D CWM filters. As examples, the detail preserving properties of some 2-D CWM filters are compared with other detail preserving filters, i.e. multilevel median filters. The generation of binary root signals of some 2-D CWM filters is treated in the term of the smallest surviving object (SSO). It is illustrated by some examples that CWM filters with different orientation of windows can be useful in image segmentation.     

Universal filters of arbitrary order and type employing square-root-domain technique

Novel Single Input Multiple Output (SIMO) and Multiple Input Single Output (MISO) universal filter topologies of arbitrary order and type are introduced in this paper. The proposed topologies have been realised by employing Square-Root Domain (SRD) technique. An offered benefit of the universal filter topologies is that only grounded capacitors are required for their implementations and the resonant frequency of the filters can be electronically controlled by an appropriate dc current. The proposed universal filters simultaneously offer all the five standard filtering functions i.e. Lowpass (LP), Highpass (HP) and Bandpass (BP), Bandstop (BS) and Allpass (AP) frequency responses. In addition, the SIMO topology is generic in the sense that it can yield four different stable filter configurations. Two design examples are provided in each configuration and the correct operation of the corresponding topologies has been evaluated through the PSPICE software with BSIM 0.35-µm CMOS process model parameters.     

Deterministic properties of separable and cross median filters with an application to block truncation coding

In this paper, we present some deterministic properties of separable and cross median filters. It is proved that in the absence of vertical binary oscillations, the roots of a separable median filter are included in a subset of root signals of the corresponding cross median filter. Moreover, the sufficient and necessary condition is given for a point to be invariant to cross median filtering. On the root structures of cross median filters, we indicate that there exist three different types of regions based on the one-dimensional features of rows and columns. Finally, an application example is discussed where the roots of separable and cross median filters are used in block truncation coding (BTC) for image compression.     

基于Daubechies尺度函数的共形MRTD方法研究及其电磁散射应用

为了降低Yee氏蛙跳式网格划分的台阶误差,该文对3维曲面导体目标进行精确电磁建模,将时域多分辨(MRTD)算法与共形时域有限差分(CFDTD)算法结合,提出一种新的基于Daubechies尺度函数的共形时域多分辨(CMRTD)方法。该文提出将基于Daubechies尺度函数的MRTD迭代公式分解为若干传统FDTD迭代公式的线性组合,然后对最里面回路上的FDTD分解式运用局部共形技术,再将各个分解式进行线性组合,从而得到CMRTD结果。仿真结果表明,CMRTD方法既保持了MRTD方法节省计算资源、计算效率高等优点,同时明显提高了计算的精度。     

Coefficients of maximally flat low and high pass nonrecursive digital filters with specified cutoff frequency

A simple and general method is presented for determining the coefficients of a lowpass or highpass maximally flat nonrecursive digital filter with a specified cutoff frequency.     

RF-MEMS谐振器和滤波器研究进展

介绍了基于梳状、梁式、圆盘三种结构的射频微机电系统( RF-MEMS)谐振器及滤波器,并对RF-MEMS谐振器及滤波器的结构与性能参数进行讨论;分析RF-MEMS谐振器及滤波器设计和制造中的有关问题及其处理方法;RF-MEMS谐振器及滤波器性能优异,能与其他器件实现片上集成,且与集成电路工艺兼容,在射频无线通信系统中的...     

Chebyshev approximation of recursive digital filters having specified amplitude and phase characteristics

The design of an IIR filter of prescribed amplitude and phase characteristics can be reduced to an approximation problem for complex valued functions. An algorithm for the solution of this problem is given and some numerical results are presented.     

Fault-based testing and diagnosis of balanced filters

The test and diagnosis of fully differential analogue filters are addressed in this paper. Full coverage of hard/soft faults affecting circuit behaviour can be achieved by adjusting the tolerance window of the built-in self-test circuitry and the amplitude and frequency of the input test signal. Under a single fault assumption, the faulty active or passive component is located and the actual defective value of a faulty passive component is determined. A test generation procedure which results in maximum fault coverage and maximal diagnosis of hard/soft faults in the filter is presented. The test and diagnosis approach can be made compatible with IEEE Std 1149.1 for boundary scan testing.This work is part of AMATIST ESPRIT-III Basic Research Project, funded by CEC under contract #8820.     

A CONFIGURATION FOR REALIZATION OF THE MULTICHANNEL AND HIGH-ORDER IIR ADAPTIVE FILTERS

This paper develops a new hyperstable adaptive algorithm which can be used inthe multichannel ⅡR conflguration and/or the high-order ⅡR or zero-pole configuration for jointprocess estimation.     

THEORY AND DESIGN OF UNIFORM FILTER BANKS USING ALL-PASS FILTERS

In this paper,the theory of uniform filter banks using all-pass tilters is furtherdeveloped.A new structure of two stage filter banks using all-pass filter is proposed,The pre-stage is half-band filter with period,the post-stage is two sets of band-pass filter banks.Thepre-stage filter stop-band just controls the don't-care-band of the post-stage filter banks usingall-pass polyphase,so as to realize a continuous stop-band property Moreover,a method ofsynthesizing filter bank is derived,which eliminates aliasing and amplitude distortions of theanalysis/synthesis system Finally,an example is given.     

Design and analysis of planar printed microwave and PBG filters using an FDTD method

In this paper, various planar printed microwave and photonic band-gap (PBG) filters have been designed and analyzed by applying the finite difference time domain method, together with an unsplit-anisotropic perfectly matched layer technique as treatments of boundary conditions. The implemented solver was first validated by comparing the computed data with those published in literature, and a good agreement was observed between the results. Then, based on the specified design criteria, various microwave and PBG filters were designed and analyzed, in which the theoretical predictions matched well with the computed results for the characteristics of the proposed filters.     

一种基于多相滤波的高效信道化算法研究及改进

本文对基于多相滤波技术的信道化算法做了仿真和优缺点分析.针对其存在盲区的问题,以降低抽取率为基础,对该算法进行了改进,建立了无盲区信道化接收机模型.并由此模型设计了四信道仿真系统,实验结果验证了模型的正确性.最后,在Tiger SHARCTS101上实现了改进算法,运行结果证明了算法的高效性.     

四方向上的任意角度扇形数字滤波器的设计

具有任意角度（扇形所围成的角度）和任意方向（扇形所取方向）的扇形数字滤波器在图像数据压缩和地质、地震等方面的数据处理中有着广泛的应用。目前，大多数的工作多集中于水平及垂直方向的９０°扇形数字滤波器的设计，因而有必要研究任意方向上的任意角度的扇形数字滤波器的设计。本文介绍利用ＭｃＣｌｅｌｌａｎ交换法设计具有垂直，水平及±４５°方向上的任意角度的扇形数字滤波器的设计方法，垂直水平方向上的扇形滤波器的设     

Some properties of Cu2SnSe3, Cu2GeSe3 and other A 2 I BIVC 3 VI compounds

Attempts were made to synthesize nine A₂ ^IB^IVC₃ ^VIcompounds (A^I = Cu,Ag; B^IV = Ge,Sn,Pb; C^VI = Se,Te) by solidification from stoichiometric melts. Ternary phases were obtained for four of the five combinations involving Cu. Ingots of Cu₂SnSe₃ and Cu₂GeSe₃ were essentially single-phase, indicating that these compounds are congruently melting. The Cu₂GeTe₃ ingot contained a small percentage of GeTe, while the ternary phase made up only about half the Cu₂SnTe₃. No ternary phase was detected for Cu₂PbSe₃ or for any of the four combinations involving Ag. The electrical resistivity and Hall coefficient have been measured down to 77 K in Cu₂SnSe₃ and Cu₂GeSe₃, and the temperature dependence indicates the presence of two band conduction. Both undoped compounds were p-type with room temperature carrier concentrations greater than 1×10¹⁸/cm³. Doping Cu₂SnSe₃ with I, Sb, In or Zn resulted in hole concentrations greater than 10²⁰/cm³. The optical absorption edge occurs at 0.5 eV for Cu₂SnSe₃ and at 0.85 eV for Cu₂GeSe₃.     

Voltage-mode high-Q band-pass filters and oscillators employing single CDBA and minimum number of components

In this paper, voltage-mode second order high-Q band pass filters and oscillators which employ only single current differencing buffered amplifier (CDBA) as the active component are proposed. One of the four filter circuits and two of the four oscillators described have minimum passive component count properties, without using the internal pole of the active element. These BP filters can be easily cascaded without any recourse to impedance matching circuitry. The circuits have been analysed theoretically, simulated and experimentally tested in a laboratory. It is shown that the results of simulations and experimental work are in agreement with theoretical predictions.