Square‐root domain wave filters

In this paper the wave method is used for designing high‐order square‐root domain filters, which emulate the topology of the corresponding LC ladder prototypes. This is achieved by transposing the signal flow graph that corresponds to the wave equivalent of the elementary two‐port subnetwork in the linear domain to the corresponding one in the square‐root domain, by employing an appropriate set of complementary operators. As the equivalents of the other reactive elements are derived from the wave equivalent of the elementary subnetwork, by interchanging the terminals of the appropriate wave signals and/or using inverters, an advantage offered by the proposed technique is the modularity of the derived filter configurations. As an example, a fifth‐order lowpass square‐root domain wave filter was designed and its behaviour was studied through simulation results in order to demonstrate the validity of the proposed design technique. Copyright © 2006 John Wiley & Sons, Ltd.     

Square‐root domain linear transformation filters

A new systematic method for designing square‐root domain (SRD) linear transformation (LT) filter is introduced in this paper. For this purpose, a substitution table containing the SRD LT equivalent of each passive element has been introduced. The proposed equivalents have been realized by employing appropriate SRD building blocks with low‐voltage operation capability. As a design example, a 3rd‐order SRD LT filter has been realized and its performance has been evaluated through simulation results. In addition, the most important performance factors of the SRD filter have been compared with those achieved by the SRD filters derived according to the leapfrog, wave, and topological emulation methods. Copyright © 2010 John Wiley & Sons, Ltd.     

Another FIR lattice structure

A new two multiplier FIR lattice structure is derived by using the digital two‐pair concept, which produces two transfer functions H_i(z) and H_i′(z) having the complementary relationship H_i′(z)=z^?iH_i(–z^?1), in contrast to the mirror image relationship, i.e. H_i′(z)=z^?iH_i(z^?1) satisfied in the conventional FIR lattice structure. The new structure should be useful in crossover networks as well as in multirate signal processing. Copyright © 2005 John Wiley & Sons, Ltd.     

Analytical synthesis of odd/even‐nth‐order elliptic Cauer filter structures using OTRAs

The operational transresistance amplifier (OTRA), the dual of the well‐known operational transconductance amplifier, is an attractive element for use in circuit design. One odd‐nth‐order and two even‐nth‐order OTRA‐R‐C or OTRA‐MOS‐C elliptic Cauer filter structures are presented using new analytical synthesis methods (ASMs). Because it is assumed in the synthesis procedure that the transresistance R_m → ∞, but in view of the fact that R_m is finite in practice, the more the number of OTRAs employed, the worse the precision of the output signals. By studying the sensitivity of the output to component variations, more precise output may be obtained by selecting one or two appropriate capacitance(s)/resistance(s) and adjusting their values suitably. H‐spice simulations are given to validate and demonstrate the theoretical predictions. Copyright © 2012 John Wiley & Sons, Ltd.     

有限长脉冲响应滤波器在视频格式转换芯片中的应用

本文提出了一种高性能有限脉冲响应(FIR)滤波器结构,用于视频格式转换芯片中尺寸缩放模块算法的实现,该结构采用流水线技术1,同时结合了并行性、系数对称性、“0”的特性和乘法优化(加法代替);阐述了该FIR滤波器的设计原则和优化方法,给出了该FIR滤波器FPGA实现的框图和综合结果,与传统结构实现的FIR滤波器比较具有更高的性能和兼容性。     

New designs of low/high‐pass and mid‐pass/stop FIR digital filters

New designs of highly efficient low/high‐ and mid‐pass/stop (centre‐symmetric band‐pass/stop) FIR non‐recursive digital filters are presented. The designs are based on the modulation property of DFT, applied to the already presented MAXFLAT halfband low‐pass filters. The presented filters have explicit formulas for their tap‐coefficients, and therefore are very easy to design. They have highly smooth frequency response and wider transition regions like MAXFLAT filters. The design formulae are modified to give new classes of low/high‐ and mid‐pass/stop filters, for which, like in equiripple filters, the transition bandwidth can be reduced by increasing the size of ripple on magnitude response. It is shown, with the help of design examples, that the performance of these filters is comparable to that of equiripple filters. Copyright © 2001 John Wiley & Sons, Ltd.     

Analytical synthesis and comparison of voltage‐mode Nth‐order OTA‐C universal filter structures

Complementary single‐ended‐input operational transconductance amplifier (OTA)‐based filter structures are introduced in this paper. Through two analytical synthesis methods and two transformations, one of which is to convert a differential‐input OTA to two complementary single‐ended‐input OTAs, and the other to convert a single‐ended‐input OTA and grounded capacitor‐based one to a fully differential OTA‐based one, four distinct kinds of voltage‐mode nth‐order OTA‐C universal filter structures are proposed. TSMC H‐Spice simulations with 0.35µm process validate that the new complementary single‐ended‐input OTA‐based one holds the superiority in output precision, dynamic and linear ranges than other kinds of filter structures. Moreover, the new voltage‐mode band‐pass, band‐reject and all‐pass (except the fully differential one) biquad structures, all enjoy very low sensitivities. Both direct sixth‐order universal filter structures and their equivalent three biquad stage ones are also simulated and validated that the former is not absolutely larger in sensitivity than the latter. Finally, a very sharp increment of the transconductance of an OTA is discovered as the operating frequency is very high and leads to a modified frequency‐dependent transconductance. Copyright © 2010 John Wiley & Sons, Ltd.     

基于MATLAB的FIR数字滤波器的方法设计

数字滤波器是一种具有选择并区分不同频率功能的电路,是在时域内过滤离散信号的数字系统。采用的是窗函数法。研究的重点目的是依据FIR滤波器的特性,分析了FIR滤波器的窗函数设计方法的介绍和选择使用,并利用MATLAB信号处理工具箱来实现验证FIRDF程序的设计。给出了详细的设计理论和具体步骤,并将设计的滤波器应用到一个混和正弦波信号,以验证滤波器的性能,实验证明该滤波器达到了预期的滤波功能。     

基于MATLAB的FIR数字滤波器设计与仿真

数字滤波器的设计和应用是数字信号处理中的核心内容之一。利用MATLAB信号处理工具箱中的FDATool工具设计出具有去噪滤波功能的有限脉冲响应滤波器,根据滤波器的不同应用需求,利用FDATool工具设计出具不同滤波功能的有限脉冲响应滤波器,并且根据设计要求和滤波器特性随时调整参数,直观简便,极大地减轻了工作量,极大方便了滤波器的设计,达到理想的应用目的。最后,对所设计的滤波器进行滤波仿真验证,对含有噪声的信号进行去噪处理,通过比较分析滤波器去噪前后信号时域及频域波形图,得出所设计的滤波器能够达到理想的去噪效果。     

一种满足功率互补特性的线性相位FIR滤波器

消除滤波器组的重构误差以实现完全重构一直是多抽样率滤波器组研究领域的一项重要课题。已有部分文献提出了分别消除幅度与相位误差行之有效的方法,然而这类方法都是在消除一种误差的基础上,使另一种误差最小化,并没有实现2种误差的完全消除。本文从功率互补性以及线性相位滤波器系数的特点出发,推导出既具有线性相位又满足功率互补性的分解滤波器组频率响应的表达式,根据频率响应表达式设计出了一种既满足线性相位又满足功率互补特性的FIR滤波器,实验表明采用该滤波器的多抽样率滤波器组具有良好的完全重构性。     

Analytical synthesis of voltage‐mode even/odd‐nth‐order differential difference current conveyor and fully differential current conveyor II‐grounded resistor and capacitor universal filter structures

A complete definition of an odd/even‐nth‐order notch or band‐reject filter transfer function is presented. Based on the differences between the input voltage and (i) an nth‐order high‐pass; (ii) a traditional nth‐order notch; and (iii) an nth‐order all‐pass filtering transfer function, a systematic method has been proposed to derive a universal filter structure that can realize voltage‐mode odd/even‐nth‐order low‐pass, band‐pass, high‐pass, all‐pass and traditional notch filters. The intrinsic capability of voltage‐mode addition and subtraction of the two active elements, differential difference current conveyors and fully differential current conveyors, is used to advantage in the aforementioned synthesis procedure. Based upon the definition of an nth‐order notch or band‐reject filter transfer function proposed in this paper, the aforementioned universal one has been further extended to the newly defined nth‐order band rejection filter. The voltage and current tracking errors of the two active elements are compensated by varying the resistances of the proposed filter. Filtering feasibility, stability, component sensitivities, linear and dynamic ranges, power consumption, and noise are simulated using H‐Spice with 0.35 µm process. Compared to some of the recently reported universal biquads, the new one is shown to enjoy the lowest component sensitivities and the best output accuracy for all‐pass signals. Moreover, Monte Carlo and two‐tone tests for intermodulation linearity simulations are also investigated. Copyright © 2014 John Wiley & Sons, Ltd.     

一种FIR高阶多通带数字滤波器的优化设计方法

为有效提高有限冲激响应FIR(FiniteImpulseResponse)高阶数字滤波器优化设计速度和精度,根据FIR线性相位滤波器的幅频特性,提出了一种基于激励矩阵为Hd-CTW的神经网络算法。该算法的主要思想是用神经网络算法优化设计的FIR滤波器的幅频特性与理想滤波器的幅频特性在整个通带和阻带范围内的误差平方和为最小,算法不涉及逆矩阵运算。为了保证该算法的收敛性,提出并证明了神经网络算法的收敛性定理,为神经网络学习率的选择提供了理论依据。该算法的主要特点是可实现样本集数据的并行训练,有效提高了计算速度。为了验证该算法的有效性,给出了多通带FIR高阶数字滤波器优化设计实例,仿真结果表明了该算法具有高的计算精度和快的计算速度。     

Design of square‐root domain filters by substituting the passive elements of the prototype filter by their equivalents

A novel technique for designing square‐root domain (SRD) filters is introduced in this paper. The concept of the proposed method is based on the substitution of the passive elements of the corresponding prototype filter by their SRD equivalents. The signal processing performed by the proposed SRD equivalents achieves that the voltage at each terminal of the SRD equivalent is the compressed version of the voltage at the corresponding terminal of the passive element, and that the current that flows through the SRD equivalent is the same as that flows through the passive element. The main attractive characteristic of the proposed method is that a quick procedure for designing SRD filters is offered. The validity of the proposed technique was verified by studying the behaviour of a 5th‐order SRD low‐pass filter. In order to demonstrate the benefits offered by the proposed technique, a SRD leapfrog filter was also designed and its performance is compared with that of the active filter that topologically simulates the same prototype filter. Copyright © 2007 John Wiley & Sons, Ltd.     

A DC stabilized log‐domain nth‐order multifunction filter based on the decomposition of nth‐order HP filter function to FLF topology

The design of high‐order log‐domain filters can be easily accomplished by transposing already known linear‐domain G_m‐C filter topologies to their counterparts in the log‐domain through the employment of a set of complementary operators. To achieve the G_m‐C filter topologies, the multiple feedback approach is widely used due to its accrued advantages. In this paper a synthesis approach for the development of an nth‐order multifunction log‐domain filter comprising lowpass (LP), highpass (HP) and bandpass (BP) filter functions is proposed. The approach is based on the decomposition of nth‐order HP filter function to follow‐the‐leader‐feedback (FLF) topology. The design is simple and simultaneously achieves nearly all of the chief advantages. The design offers superior performance factors vis‐à‐vis the ones recently reported. To verify the high‐order behavior of the topology, a 5th‐order multifunction filter was designed and the achieved simulated results verify the theory. Copyright © 2008 John Wiley & Sons, Ltd.     

Cumulant‐based approach to FIR system identification

In this paper, a non‐recursive approach is developed for estimating the coefficients of a moving average (MA) model from only third‐order cumulant statistics of a finite realization of the observations of the output data. The signal observations may be noisy. The excitation signal is assumed to be zero mean, non‐Gaussian stationary sequence that is not observed. The noise is additive and may be coloured Gaussian or non‐Gaussian. This novel technique is based on forming a third‐order cumulant composite data matrix. The method presented here requires the solution of a system of linear equations, which can be achieved using least‐squares methods. The proposed approach is illustrated via computer simulations and is shown to be consistent. Copyright © 2003 John Wiley & Sons, Ltd.     

基于FPGA的FIR滤波器FFT与DA算法的比较

本文利用FPGA实现了基于FFT算法与DA的FIR滤波器,在此基础上进行了规模和速度上的改进。通过MATLAB与MAX PLUSⅡ的联合仿真,验证了FPGA的实现方案是可行的和高效的。比较了两种算法在资源消耗以及速度方面各自的优越性。结果表明,采用基于DA蝶形处理器的并行FFT算法实现的64阶FIR滤波器使用了1869个LC,基于规模改进DA实现的同阶FIR滤波器使用了1428个LC,前者的使用资源多但速度优于后者。     

基于FPGA的分布式算法FIR滤波器设计

FIR滤波器具有许多优点,是数字信号处理系统中基本的元件。本文比较了目前FIR滤波器硬件实现的几种方法,详细研究了基于FPGA、采用分布式算法实现FIR滤波器的原理和方法,设计了一个32阶线性相位FIR滤波器,并用VHDL语言对其进行了描述。此滤波器采用串行加法器将数据进行预相加,从而将滤波器的规模减半。其主要部分——乘累加单元,采用LUT查找表结构,将乘法运算转换为查表操作,提升处理速度。最后进行了硬件仿真,结果证明,这一方法是可行且高效的。     

Explicit design formulas for current‐mode leap‐frog OTA‐C filters and 300 MHz CMOS seventh‐order linear phase filter

The leap‐frog (LF) configuration is an important structure in analogue filter design. Voltage‐mode LF OTA‐C filters have recently been studied in the literature; however, general explicit formulas do not exist for current‐mode LF OTA‐C filters and there is also need for current‐mode LF‐based OTA‐C structures for realization of arbitrary transmission zeros. Three current‐mode OTA‐C structures are presented, including the basic LF structure and LF filters with an input distributor or an output summer. They can realize all‐pole characteristics and functions with arbitrary transmission zeros. Explicit design formulas are derived directly from these structures for the synthesis of, respectively, all‐pole and arbitrary zero filter characteristics of up to the sixth order. The filter structures are regular and the design formulas are straightforward to use. As an illustrative example, a 300 MHz seventh‐order linear phase low‐pass filter with zeros is presented. The filter is implemented using a fully differential linear operational transconductance amplifier (OTA) based on a source degeneration topology. Simulations in a standard TSMC 0.18µm CMOS process with 2.5 V power supply have shown that the cutoff frequency of the filter ranges from 260 to 320 MHz, group delay ripple is about 4.5% over the whole tuning range, noise of the filter is 420nA/√Hz, dynamic range is 66 dB and power consumption is 200 mW. Copyright © 2008 John Wiley & Sons, Ltd.     

FIR数字滤波器的优化与验证

引入数字滤波器的基本概念和其在工程应用中的作用,阐述FIR数字滤波器的基本结构和设计原理,介绍优化的各种算法,通过VHDL硬件描述语言实现,并利用FPGA对不同的优化设计实例给予验证,仿真。判断仿真验证优化的可靠性,提交综合报告,进一步分析造成优化差异的本质原因,根据优化的特点选择不同工程背景下的滤波器设计优化方法。     

基于ARM的上下频率可调FIR滤波器设计与仿真

在脑电信号的检测处理过程中,信号滤波是重要工作之一。结合ARM及软件仿真的特点,提出一种综合使用MATLAB和EVC软件在ARM上实现上下频率可调FIR滤波器的设计方法。先用MATLAB软件设计出满足性能要求的滤波器参数,然后在ARM中进行滤波算法的C++语言编程,再在EVC软件中进行仿真实验。实验结果表明,该滤波器各项性能良好,对实际系统设计具有较好参考意义,能够满足脑电信号采集系统信号预处理的要求。