Frequency grid density for the design of 2-D FIR filters

In the design of a digital 2-D FIR filter, the frequency response is often optimised to satisfy a given set of specifications on a dense grid of frequency points. The accuracy of a filter design improves when there are more grid points, but this is at the expense of higher computational resources. The authors present the relationship between the accuracy and the frequency grid density in 2-D filter designs. A new formula for determining the frequency grid spacing is also proposed     

Design of Microwave Filters With Arbitrary Frequency Response Based on Digital Methods

This letter presents a novel general technique for the design of microwave filters with arbitrary frequency response. It is based on the translation of the microwave specifications to the digital domain, where the well known and readily available digital filter design techniques are applied. By means of these digital techniques, the method provides a straightforward procedure to calculate the poles and zeros corresponding to the analog frequency response that satisfies the target specifications. From the poles and zeros, the microwave filter can be readily obtained using conventional techniques. As an example to demonstrate the proposed technique, a filter with user-defined specifications over two independent passbands has been implemented and successfully tested in microstrip technology.     

A new method for the design of IIR filters with flat magnitude response

This paper presents a new direct design of infinite-impulse response (IIR) filters with a flat magnitude response in both passband and stopband (Butterworth filters). The design specifications are passband and stopband frequencies and passband droop and stopband attenuation. The approach is based on an allpass filter with flatness at frequency points /spl omega/=0 and /spl omega/=/spl pi/. Depending on the parity of the IIR filter order, the allpass filter is either real or complex. However, in both cases, the resulting IIR filter is real.     

PCLS IIR digital filters with simultaneous frequency responsemagnitude and group delay specifications

This paper presents the peak-constrained least-squares (PCLS) approach to designing IIR digital filters. PCLS IIR digital filters that meet simultaneous specifications on the frequency response magnitude and the group delay are introduced. As a point of reference, we consider the IIR digital filter design problem that appears in Deczky's (1972) classic paper and in the popular textbook by Oppenheim and Schafer (1989). In addition, the same design problem appears in the IIR filter design chapter by Higgins and Munson (1993) in the Handbook for Digital Signal Processing. By using our new algorithm with simultaneous optimization of the frequency response magnitude and the group delay, we obtain a dramatic improvement in the solution of this classic IIR digital filter design problem. Starting from the same filter structure and the same specifications for the frequency response magnitude as in the works of Deczky, Oppenheim and Schafer, and Higgins and Munson, we are able to reduce the group delay ripple by a factor of 35. In another design problem that originated in Deczky's work, we use PCLS optimization to reduce the group delay ripple by a factor of 40 at the same time we reduce the stopband energy by 6 dB, without sacrificing any other performance measure. The group delay ripple in this IIR digital filter example is reduced to only ±0.002 samples     

Design of linear-phase IIR filters via impulse-response gramians

A new method for the design of a linear-phase infinite-impulse-response (IIR) filter is presented. It involves designing a finite-impulse-response (FIR) filter satisfying the given frequency response specifications and subsequently obtaining a significantly lower order IIR filter using model reduction based on impulse-response gramians. The general outline of the method and a brief overview of the existing linear-phase FIR filter design and model-reduction techniques are presented. The impulse-response gramian and the model-reduction algorithm used are presented. The method is illustrated by design examples and is compared with other methods for the design of linear-phase IIR filters using equalizers     

基于Matlab的加速度传感器振动信号处理方法研究

介绍了一种用Matlab信号处理工具箱进行数字滤波器设计的方法。给出了工具箱中的FDATool图形用户接口的详细使用方法,用FDATool进行滤波器设计,可以随时对比设计要求和滤波器特性调整参数,直观简便,在每次改变参数时,由于计算机的超强运算能力,只需点击设计按钮,新的滤波器立即产生,避免了传统滤波器设计的大量手工运算。并用他设计出了满足性能要求的低通数字滤波器,实现了对加速度传感器干扰振动信号的滤除,解决了工程实际问题。     

Optimization-based design and implementation of multidimensional zero-phase IIR filters

This paper considers multidimensional infinite-impulse response (IIR) filters that are iteratively implemented. The focus is on zero-phase filters with symmetric polynomials in the numerator and denominator of the multivariable transfer function. A rigorous optimization-based design of the filter is considered. Transfer function magnitude specifications, convergence speed requirements for the iterative implementation, and spatial decay of the filter impulse response (which defines the boundary condition influence in the spatial domain of the filtered signal) are all formulated as optimization constraints. When the denominator of the zero-phase IIR filter is strictly positive, these frequency domain specifications can be cast as a linear program and then efficiently solved. The method is illustrated with two two-dimensional IIR filter design examples.     

基于遗传算法的递归式MTI滤波器的设计

递归式MTI滤波器从理论上讲几乎可以合成任意形状的频率响应函数,因而具有很广的应用范围。为了能够灵活设计出满足系统要求的递归式MTI滤波器,提出了一种设计方法。该方法以遗传算法(GA)的基本思想为基础,利用滤波器的改善因子、通带宽度和通带波纹来构成适应函数,并用GA来加快参量搜索速度和获取全局近似最优解。实验仿真设计了两种典型的递归式MTI滤波器,结果证明该方法是一种有效的设计方法,它可以灵活而快速地设计出所需要的滤波器。     

A singular value decomposition derivation in the discrete frequencydomain of optimal noncentro-symmetric 2-D FIR filters

A new derivation is presented for the least squares solution of the design problem of two-dimensional (2-D) finite impulse response (FIR) filters by minimizing the Frobenius norm of the difference between the matrices of the ideal and actual frequency responses sampled at the points of a frequency grid. The mathematical approach is based on the singular value decomposition (SVD) of two complex transformation matrices. Interestingly, the designed filter is proved to be zero-phase if the ideal filter is so without assuming any kind of symmetry     

Acoustic-surface-wave television filters

A computer optimisation procedure is described which has been successfully used to synthetise acoustic-surface-wave filters according to French television specifications. A model for interdigital transducers is used which reduces the synthesis problem to that of finding a set of transducer dimensions. The experimental frequency response of such a filter is in good agreement with the predictions.     

Almost Equiripple Low-Pass FIR Filters

An approximation of the linear phase almost equiripple low-pass finite impulse response filter is introduced. The frequency response of an almost equiripple low-pass finite impulse response filter closely approaches the frequency response of an optimal equiripple low-pass finite impulse response filter in the Chebyshev sense. The presented approximation is based on the generating polynomial. Despite that the generating polynomial has no iso-extremal behavior, it is related to the class of iso-extremal polynomials. The zero phase transfer function of an almost equiripple low-pass finite impulse response filter follows from the generating polynomial. The closed form solution for the direct algebraic computation of the impulse response of the filter has been developed on the basis of generalization of the differential equation suitable for the half-band specifications. No numerical procedures are involved. The practical design procedure based on the developed approximation is presented. For illustration of the design procedure one example of the design is included here.     

耦合谐振带通滤波器的EDA设计

滤波器是合成频率源中重要的部件,通常用来充分抑制不需要的谐波和杂散,提取出需要的频率分量.随着计算机和EDA技术的迅猛发展,设计滤波器可以使用EDA工具进行仿真,其结果与实际情况非常接近.本文根据滤波器设计的基本原理,借助商用全波电磁场分析软件设计了几种形式的同轴腔体带通滤波器,过程简单,设计周期短,实测结果也比较理想.     

Obtaining expert advice [filter synthesis]

Unlike other filter-synthesis design tools, EXSHOF employs knowledge-based synthesis of a high-order active filter. The package is completely menu driven and extremely user friendly. At the various stages of filter design it asks questions of the user and provides guidelines to these questions; i.e., it gives expert help in making decisions. It assumes that the user has little knowledge of computers and filters. Users have the option of using any of the five approximation functions or directly inputting the transfer function. It can design four types of different high-order filter structures and nine different biquad circuits. The detailed diagram of the designed circuit is presented to the user in a modular form using graphics. The frequency response of the circuit has been simulated using PSpice and it has been found that the response exactly matches the input specifications     

A Harmonic Rejection Filter Designed by an Exact Method

An exact design procedure for band-stop filters is used to design a transmission-line filter with one point of perfect match at a fundamental frequency and one point of infinite attenuation at a harmonic frequency. This design method is based on the mapping of the response of a low-pass prototype into that of a transmission line filter. Here a three-element Chebyshev filter is chosen as the prototype and the otherwise general procedure is adapted for the special case of rejection of the second harmonic.     

Low-Complexity Design of Variable Bandedge Linear Phase FIR Filters With Sharp Transition Band

This paper presents a very low-complexity design of variable bandedge linear phase finite-impulse-response (FIR) filters with fixed sharp transition width. The idea is to first decompose the input signal into several channels in the frequency domain. The channel(s) involved with the transition band of the variable filter due to the variation of the bandedge is (are) shaped to produce the required transition band, and then summed up with the channels involved with the passband of the variable filter to produce the required frequency response. The proposed variable filter has extremely low complexity when the transition band is sharp, if compared with other techniques such as the Farrow structure. It is possible that the computational complexity of the variable filter is even lower than that of a corresponding fixed filter with the same transition width and ripple specifications implemented in its direct form.      

动目标检测(MTD)滤波器组的优化设计新算法

本文提出了一种MTD滤波器组的优化设计新算法。它可强制滤波器组的频率特性在零频形成零点并使旁瓣面积最小。与Remez多重变换算法相比,在主瓣面积相近的条件下,MTD系统对各种地杂波的平均改善因子提高了约4dB。该优化算法已用于某实际的雷达MTD系统之中并获得了满意的性能。     

Digital filter design techniques in the frequency domain

Digital filtering is the process of spectrum shaping using digital components as the basic elements. Increasing speed and decreasing size and cost of digital components make it likely that digital filtering, already used extensively in the computer simulation of analog filters, will perform, in real-time devices, the functions which are now performed almost exclusively by analog components. In this paper, using the z-transform calculus, several digital filter design techniques are reviewed, and new ones are presented. One technique can be used to design a digital filter whose impulse response is like that of a given analog filter; other techniques are suitable for the design of a digital filter meeting frequency response criteria. Another technique yields digital filters with linear phase, specified frequency response, and controlled impulse response duration. The effect of digital arithmetic on the behavior of digital filters is also considered.     

用AOA设计有源补偿双二阶电流模式滤波器

为获得高频率、高精度双二阶电流模式滤波器,根据实际伴随运算放大器(AOA)的开环频率特性,先分析了实际AOA积分器的频率特性,后分析了有源补偿的AOA积分器的频率特性。再借助于拆环法,通过巧妙设计,给出了AOA有源补偿双二阶电流模式滤波器。最后采用预失真技术,使该电路的实际参数与设计值完全吻合。计算机仿真表明,所提出的电路正确有效。     

Frequency sampling method for designing 2-D FIR real-coefficientdigital filters using Hermite interpolation

A novel frequency-sampling method for designing 2-D real-coefficient FIR filters, given the values and slope estimates of the desired frequency response at each of the node points of a rectangular grid, is presented. Based on a new class of bivariate Hermite-type polynomials suitable for interpolating at complex conjugate points, and using Kronecker products, the original 2-D filter design problem is reduced to the solution of two 1-D systems of linear equations. Additional advantages of the method are the securing of the existence and uniqueness of the solution of the design problem, computational efficiency, the use of simple and recursive 1-D algorithms; the guarantee of real accurate results; and the inherent parallelism. The method is also applied to design 2-D symmetric FIR filters and can be extended to m-D design problems     

Frequency Domain FIR Filter Design Using Fuzzy Adaptive Simulated Annealing

An alternative approach to digital filter design is presented. The overall technique is as follows: Starting from frequency domain constraints and a parameterized expression of the filter family under adaptation, a corresponding training set is created, an error function is synthesized and a global minimization process is executed. At the end, the point that minimizes globally the particular cost function at hand determines the optimal filter. The adopted numerical optimization algorithm is based upon the well-known simulated annealing paradigm and its implementation is known as fuzzy adaptive simulated annealing. Although it is used in this paper to fit FIR filters to frequency domain specifications, the method is suitable to application in other problems of digital filter design, where the matter under study can be stated as finding the global minimum of a numerical function of filter parameters. Design examples are shown to verify the effectiveness of the proposed approach.