Filter Design Approach Research Articles

Performance of Multiplierless FIR Filter Based on Directed Minimal Spanning Tree: A Comparative Study

This paper presents a novel low complex configuration methodology by deploying a directed minimal spanning tree (DMST) algorithm for designing digital multiplierless finite impulse response filter. This method utilizes the shift inclusive differential coefficient and common sub-expression elimination (CSE) technique to minimize the multiple constant multiplications using steepest decent approach. The attractive feature of this work lays on the detailed comparison of the cost, reconstruction error, pass-band and stop-band error by exploiting various evolutionary techniques such as cuckoo search algorithm, particle swarm optimization, artificial bee intelligence, hybrid swarm optimization and flower pollination algorithm; followed by employing hybrid SID and DMST on these techniques. For this purpose, a mean squared error-based objective function is optimized in the pass-band and stop-band region of the filter. Further, a detailed comparison of hybrid SID and DMST with other existing CSE algorithms is also illustrated. It has been observed that up to 80% reduction in number of adders can be accomplished using the proposed DMST-based approach for multiplierless filter design.

An Evolutionary EMI Filter Design Approach Based on In-Circuit Insertion Loss and Optimization of Power Density

Power density is one of the most significant issues in designing electromagnetic interference (EMI) filters for power electronic-based applications. Therefore, an effective EMI filter design should consider both its capability to ensure the compliance with the related EMI standard limits and the possibility to build it by suitable components leading to the most compact configuration as well. To fulfill the above requirements, in this paper, an automatic procedure to get an improved design of EMI filters is proposed. Specifically, according to the proposed method, the values of filter parameters for both common mode (CM) and differential mode (DM) sections are selected by a genetic algorithm (GA) exploiting the in-circuit insertion loss, thus obtaining a more effective design. Besides, the components that set up the filter are selected by a rule-based procedure searching through a suitable database of commercial components to identify those allowing for the maximum power density. Experimental tests were performed using an inverter-fed induction motor drive as a case study, and the obtained results have demonstrated the validity of the proposed approach.

An Exact Characterization of the L 1/L₋ Index of Positive Systems and Its Application to Fault Detection Filter Design

In this brief, the problem of the $L_{1}/L_{-}$ fault detection for positive systems is revisited. In the existing literature, the $L_{1}$ -gain and $L_{-}$ index for positive systems are often characterized separately, and thus their linear programming descriptions involve different Lyapunov vectors. This casts the fault detection filter design as a bilinear optimization problem. To circumvent this obstacle, we first show that, for an externally positive system, the $L_{1}$ -gain and $L_{-}$ index are determined, respectively, by the largest and smallest column sums of the static gain matrices. Based on this fact, an exact characterization is given for the $L_{1}/L_{-}$ index for positive systems in terms of a linear program with equality constraints. The new characterization only involves one single Lyapunov vector, and thus renders the fault detection filter design problem convex. In addition, we find that the maximum fault sensitivity (characterized by the $L_{-}$ index from the fault to the residual) that can be achieved by the filter design approach is proportional to the required upper bound on the $L_{1}$ -gain from the disturbance to the residual. Finally, an illustrative example of a positive electric circuit is presented to show the effectiveness of the theoretical results.

Acoustic feedback path modeling for hearing aids: Comparison of physical position based and position independent models.

Acoustic feedback in hearing aids occurs due to the coupling between the hearing aid loudspeaker and microphones. In order to reduce acoustic feedback, adaptive filters are often used to estimate the feedback path. To increase the convergence speed and decrease the computational complexity of the adaptive algorithms, it has been proposed to split the acoustic feedback path into a time-invariant fixed part and a time-varying variable part. A key question of this approach is how to determine the fixed part. In this paper, two approaches are investigated: (1) a digital filter design approach that makes use of the signals of at least two hearing aid microphones and (2) a defined physical location approach using an electro-acoustic model and the signals of one hearing aid microphone and an additional ear canal microphone. An experimental comparison using measured acoustic feedback paths showed that both approaches enable one to reduce the number of variable part coefficients. It is shown that individualization of the fixed part increases the performance. Furthermore, the two approaches offer solutions for different requirements on the effort to a specific hearing aid design on the one hand and the effort during the hearing aid fitting on the other hand.

Multi-objective design approach of passive filters for single-phase distributed energy grid integration systems using particle swarm optimization

This article presents a non-conventional design approach of high order passive filters incorporated with distributed energy grid integration systems based on particle swarm optimization (PSO) as one of multi-objective evolutionary search algorithms. Two topologies of passive grid filters (third order passive damped LCL-filter and trap filter) are chosen as case studies. The presented grid filter design is based searching the optimum values of filter passive elements that can optimize an objective function composed of several terms such as harmonic attenuation factor and size (value) of passive elements (inductors and capacitors). The employed multi-objective design approach has three main advantages: (1) The PSO algorithm offers several groups of solutions to the same optimization problem. Accordingly, the most convenient solution can be chosen based on several factors such as cost of realization, availability in the market and the corresponding THD of grid current. (2) Multi-objective design approach is flexible enough to include other factors in the customized objective function to achieve different design criteria in accordance with new (or updated) versions of grid codes. (3) The PSO algorithm converges to the optimum solution(s) regardless the initial search values (initial guess). Consequently, the algorithm does not need any prior knowledge about filter numerical valuesThe PSO algorithm has been developed in Matlab®, while the overall hardware grid-integration system has been modeled and studied using PSIM® software package. The obtained results demonstrate the effectiveness of the proposed approach to get practical and applicable values of filter components that result in good harmonic attenuation and satisfy the related codes of grid integration such as the IEEE standard 519.The main contribution of this paper is the utilization of evolutionary optimization technique to achieve an optimum design of passive grid filters that can optimize simultaneously several contradictory goals such as achieving the maximum possible harmonic attenuation at the lowest possible filter size. Compared with conventional design approach, the PSO-based filter design approach results in lower numerical values of filter components, which leads to considerable reduction in the size and cost of the passive grid filter. Moreover, grid filter design based on evolutionary search approach permits accommodation of several design criteria in the customized objective function with arbitrary weighting factors upon system design requests and new grid codes constrains.

A novel singular spectrum analysis-based multi-objective approach for optimal FIR filter design using artificial bee colony algorithm

Effective filter design plays an important role in signal processing applications. Multiple parameters must be considered to control the over-frequency response of the designed filter. In this study, a novel multi-objective approach is proposed for windowing finite impulse response (FIR) filter design. The windowing FIR filters are commonly used due to its linear phase property, frequency stability and easier implementation. However, windowing method can only control the cutting frequency of filter, and it suffers from the problem of insufficient control of the transition bandwidth, pass and stop band cutoff frequencies. Therefore, the window function was optimized using a novel multi-objective artificial bee colony (ABC) algorithm based on singular spectrum analysis (SSA) to eliminate these disadvantages of the windowing method. The proposed method was compared to three other multi-objective ABC variants. Novel SSA-based multi-objective approach yielded the best performance among four approaches. The proposed multi-objective approach that uses the SSA method has a significant advantage since it does not require user experience, it is not dependent on parameters, and there is no weight determination problem. Also, it does not have sorting and pooling stages that increase the cost of calculation. The obtained results were compared with the published literature studies. The SSA-based multi-objective approach offered better alternative to other literature techniques in terms of calculating the fitness function that deals with finding the most reasonable solution considering all error terms. Finally, the performance of the designed filter was tested on electroencephalography (EEG) signal. The EEG signal was decomposed successfully into subbands using proposed filter design approach. Based on numerical results of this study, the proposed filter provided the low-pass band and stop band ripple, and high stop band attenuation value of all, while having well enough performance.

Enhanced transmitting and blocking filter design approach for laser scanning applications based on combining GSM and AFGSM methods

We present a design approach consisting of one-dimensional photonic crystal filters for Laser Scanning Microscopy (LSM) applications. The proposed approach based on Auxiliary Functions of Generalized Scattering Matrix (AFGSM) method provides significant flexibility in modeling desired transmission band while offering widened stop-bands. Strict spectral filter characteristics are effectively achieved by the proposed design approach without implementing commonly used complex optimization algorithms. We attest the performance of the suggested technique through designing four different filters that are commonly used in laser scanning microscopy applications; namely a laser line filter tuned to 800 nm wavelength for reflectance confocal microscopy, a bandpass filter tuned to 400 nm wavelength for second harmonic generation microscopy, a laser block filter centered to 800 nm wavelength and a dichroic filter blocking 350–400 nm while transmitting higher wavelengths for multiphoton microscopy. We demonstrate the validity and applicability of the proposed design approach considering the characteristics of the commercial optical filters.

A Simulation-Based Multifunctional Differential Mode and Common Mode Filter Design Method for Universal Converters

Existing filter design methods for grid-tied power converters either focus on grid current harmonic suppression or electromagnetic interference (EMI) noise attenuation. This article proposes a simulation-based, multifunctional filter design method, which can simultaneously handle multiple objectives, including minimizing grid current total harmonic distortion (THD), conductive EMI noise, ground leakage current, touch current, filter weight, and so on. By modeling equivalent filter circuit and simulating in the Powersim (PSIM) software, the approach avoids traditional complicated circuit analysis and mathematical computation. In addition, unlike most existing filter design approaches that only focus on one specific application or converter topology, this filter design method is a generalized approach and can also be used for universal converters that have variable applications. To demonstrate this feature, the filter design method is applied to a recently proposed series-capacitive-link universal converter. Experimental results verify the effectiveness of the proposed method.

Event-based reduced-order fuzzy filtering for networked control systems with time-varying delays

This paper investigates the event-based reduced-order fuzzy filtering problem for nonlinear networked control systems with network-induced time-varying delays. A novel fuzzy filter design approach is proposed to analyze the fuzzy systems under a reduced-order scheme. The problem of mismatched membership functions is presented in the fuzzy filtering to simplify implementation complexity and increase design flexibility of the designed reduced-order filter. In addition, the integrands of the Lyapunov–Krasovskii functional are dependent of membership functions and the existence conditions of the fuzzy filtering are given by utilizing a linearization approach. Compared with the existing reduced-order filter design approaches, the time-derivatives of membership functions are considered in the analysis process for reducing the conservativeness of obtaining the maximum delay bounds. Finally, a simulation result is given to show the effectiveness and advantages of the analysis scheme.

Single-/Multi-Band Bandpass Filters and Duplexers With Fully Reconfigurable Transfer-Function Characteristics

This paper reports on the RF design of fully reconfigurable quasi-elliptic-type single- and multi-band microwave bandpass filters (BPFs) and duplexers. They are based on series-cascaded resonators and multi-resonant/multi-band cells that produce frequency-reconfigurable poles and transmission zeros (TZs). By appropriately tuning the resonant frequencies of their constituent resonators, multiple levels of transfer-function adaptivity can be obtained. These capabilities include center-frequency and bandwidth tuning, as well as intrinsic RF switching-off (i.e., without the use of RF switches). As opposed to conventional BPF tuning mechanisms, the aforementioned reconfiguration characteristics avoid the use of tunable couplings. The basic operating principles of the engineered resonator-cascade BPF concept are presented through a three-pole/two-TZ example. Afterward, methods for expanding the proposed filter design approach to higher order, multi-band, and multi-port (e.g., duplexers) realizations are explained through coupling-matrix-based analysis. For practical-demonstration purposes, four L-band tunable microstrip prototypes were developed and measured. They include: 1) a five-pole/four-TZ BPF; 2) a five-pole/two-TZ BPF; 3) a dual-band BPF with two three-pole/two-TZ passbands; and 4) an RF duplexer.

A New Iterative FIR Filter Design Approach Using a Gaussian Approximation

The letter presents a novel iterative methodology for the design of FIR filters based on an approximation of the desired filter frequency response using a Gabor system generated by the Gaussian function. The proposed method exhibits simplicity of implementation, comparable to that of window-based design methods and ensures accuracy in the fulfillment of design requirements, comparable to the one achieved by the Parks–McClellans method. Furthermore, two other advantages of this method are: closed-form formula for the tap coefficients of the filter and the smooth, monotonically decreasing behavior of the frequency response from dc to infinite frequency.

Hybrid-driven [formula omitted] filter design for T–S fuzzy systems with quantization

This paper is mainly concerned with hybrid-driven H∞ filtering for a class of Takagi–Sugeno (T–S) fuzzy systems with quantization. To reduce the redundancy of transmission data and save the network bandwidth, a hybrid-driven scheme and a logarithmic quantizer are introduced in this paper. Firstly, by taking the effect of hybrid-driven scheme and quantization into consideration, a mathematical H∞ filter model for T–S fuzzy systems is constructed. Secondly, by applying Lyapunov stability theory, sufficient conditions for asymptotical stabilization of desired system are obtained. Moreover, an explicit algorithm for H∞ filter design is presented with the help of linear matrix inequality (LMI) techniques. Finally, numerical and physical simulations show the usefulness of the proposed filter design approach.

A Low-Loss Bandpass Filter using Edge-Coupled Resonator With Capacitive Feeding in (Bi)-CMOS Technology

In this Letter, a flexible approach for low-loss on-chip bandpass filter (BPF) design in CMOS technology is presented. The proposed approach takes the advantages of a combination of an edge-coupled electromagnetic structure, namely resonator, and a pair of metal–insulator–metal capacitors for BPF implementation. To demonstrate the insight of the approach, the designed resonator is analyzed in details by means of a simplified equivalent LC-circuit model. Then, the impact on the BPF design due to the variations of the feeding capacitance is investigated. To prove the concept, both the resonator and BPF are fabricated in a standard 0.13- $\mu \text{m}$ CMOS technology. The measured results show that the designed resonator can generate a notch with 20-dB attenuation at 59.4 GHz, while the BPF has a center frequency of 35.4 GHz with an insertion loss of 1.7 dB. The chip size of both devices, excluding the test pads, is only 0.039 mm2 ( $0.15 \times 0.26$ mm2).

Experimental demonstration of narrow-band rugate minus filters using rapidly alternating deposition technology**Project supported by the Postdoctoral Science Foundation of China (Grant Nos. 2016M592528 and 2016M602517), the Natural Science Foundation of Guangdong Province, China (Grant No. 2017A030310130), and the National Natural Science Foundation of China (Grant No. 11705259).

The design, fabrication and performance of narrow-band rugate minus filters are investigated in this paper. A method of fabricating graded-index coatings by rapidly alternating deposition of low (SiO2) and high (Al2O3) refractive index materials is presented to fabricate a rugate structure. The narrow-band rugate minus filter design and fabrication approaches are discussed in detail. The experimental results, including transmittance spectrum, surface damage test and damage morphology investigated with a scanning electron microscope, demonstrate the high performance of the as-fabricated spatial filter and confirm the feasibility of the fabrication method for narrow-band rugate minus filters.

Filter bank SCFDMA: an efficient uplink strategy for future communication systems

This paper develops a generalized system model for the precoded multicarrier communication system, using basic multirate building blocks. Mathematical analysis of the proposed model is carried out, and the results are utilized in developing an efficient uplink wireless communication standard filter bank single carrier frequency division multiple access. The proposed system combines the low peak to average power ratio (PAPR) advantage of a single carrier communication system with the reduced out of band emission (OBE) of filter bank multicarrier (FBMC) scheme. The sensitivity of the proposed system to carrier frequency offset (CFO) is analyzed, and the results are utilized in developing a CFO compensation scheme with reduced complexity. A Nyquist filter design approach, which strikes a balance between OBE and tail size, is developed and is incorporated into the proposed system to enhance the OBE and PAPR characteristics. The instantaneous power of the proposed system is theoretically analyzed using characteristic function based approach, and the effectiveness of modifications is substantiated. A detailed simulation study is carried out to validate the performance of the proposals.

FPGA based Synthesize of PSO Algorithm and its Area-Performance Analysis

Digital filters are the most significant part of signal processing that are used in enormous applications such as speech recognition, acoustic, adaptive equalization, and noise and interference reduction. It would be of great benefit to implement adaptive FIR filter because of self-optimization property, linearity and frequency stability. Designing FIR filter involves multi-modal optimization problems whereas conservative gradient optimization technique is not useful to design the filter. Hence, Particle Swarm Optimization (PSO) algorithm is more flexible and optimization technique based on population of particles in search space and alternative approach for linear phase FIR filter design. PSO improves the solution characteristic by giving a novel method for updating swarm’s position and velocity vector. Set of optimized filter coefficients will be generated by PSO algorithm. In this paper, PSO based FIR Low pass filter is efficiently designed in MATLAB and further Xilinx System Generator tool is used to efficiently design, synthesize and implement FIR filter in FPGA using SPARTEN 3E kit. For an example specifications, output of PSO algorithm is obtained that is set of optimized coefficients whose response is approximating to the ideal response. Hence, functional verification of the proposed algorithm has been performed and the error between obtained filter and ideal filter is minimized successfully. This work demonstrates the effectiveness of the PSO algorithms in parallel processing environment as compared to the Remez Exchange algorithm.

Compact wideband bandpass filter based on double-T-shaped stub loaded resonator and loading technique for zero-voltage point

In this article, a double-T-shaped stub centrally loaded uniform impedance resonator (UIR) is introduced and its resonant characteristics are well clarified, which provided a simple approach for triple-mode wideband bandpass filter (BPF) design. The double-T-shaped stub consists of a T-shaped stub at the center of UIR and two shunt uniform-impedance stubs at the T-shaped stub. Furthermore, loading technique for zero-voltage point is employed to guide design procedure from UIR to the proposed resonator. The resonant frequencies of the first three modes for the resonator can be free to adjust by the length of the UIR and the two kinds of stub. Finally, a compact wideband BPF is designed, fabricated, and measured. The measured results are in good agreement with the full-wave simulation results. The realized wideband filter exhibits a 3 dB fractional bandwidth of 69.1% with good in-band filtering performance, wide stopband, and sharp out-of-band rejection skirt.

Bandpass Filters Designed by Transmission Zero Resonator Pairs With Proximity Coupling

The concept of transmission zero resonator pair (TZRP) is used in this paper. Based on this TZRP, a new method to induce a passband is demonstrated, by which different types of bandpass filters can be designed. The proposed TZRP is structured by a pair of resonators with different resonant frequencies, which lead not only to two transmission zeroes, but also to a transmission pole between them. Passband filters can then be built by designing the proximity coupling between the TZRPs, as the TZRP works as a basic resonant element. The passband of these filters can be flexibly controlled by the resonators of TZRPs, which determine the locations of the transmission zeroes and poles. By carefully allocating the transmission zeroes, high selectivity and large out-of-band rejection can be realized. This design method is applied to design filters in two different transmission media, namely, microstrip line and rectangular waveguide. Simulated and measured results demonstrate the effectiveness of this new approach of bandpass filter design. The designed filters have the properties of small size, easy fabrication, low cost, and low loss.

A Frequency-Dependent Filter Design Approach for Norm-Optimal Iterative Learning Control and Its Fundamental Trade-Off Between Robustness, Convergence Speed, and Steady-State Error

This paper focuses on norm-optimal iterative learning control (NO-ILC) for single-input-single-output (SISO) linear time invariant (LTI) systems and presents an infinite time horizon approach for a frequency-dependent design of NO-ILC weighting filters. Because NO-ILC is a model-based learning algorithm, model uncertainty can degrade its performance; hence, ensuring robust monotonic convergence (RMC) against model uncertainty is important. This robustness, however, must be balanced against convergence speed (CS) and steady-state error (SSE). The weighting filter design approaches for NO-ILC in the literature provide limited design freedom to adjust this trade-off. Moreover, even though qualitative guidelines to adjust the trade-off exist, a quantitative characterization of the trade-off is not yet available. To address these two gaps, a frequency-dependent weighting filter design is proposed in this paper and the robustness, convergence speed, and steady-state error are analyzed in the frequency domain. An analytical expression characterizing the fundamental trade-off of NO-ILC with respect to robustness, convergence speed, and steady-state error at each frequency is presented. Compared to the state of the art, a frequency-dependent filter design gives increased freedom to adjust the trade-off between robustness, convergence speed, and steady-state error because it allows the design to meet different performance requirements at different frequencies. Simulation examples are given to confirm the analysis and demonstrate the utility of the developed filter design technique.

A New Fuzzy H∞ Filter Design for Nonlinear Time-Delay Systems with Mismatched Premise Membership Functions

This paper is concerned with the fuzzy H∞ filter design issue for nonlinear systems with time-varying delay. To overcome the limitations of conventional methods with matched preconditions, the filter to be designed and the T-S fuzzy model are assumed to have different premise membership functions and different number of rules. Hence, greater design flexibility can be obtained. Moreover, in order to reduce conservatism, a novel integral inequality which is tighter than the traditional inequalities derived from the Leibniz-Newton formula is applied. Furthermore, the proposed filter design approach also considered the information about the membership functions, which can help further relax the derived results. Finally, two numerical examples are provided to demonstrate the effectiveness and superiority of the proposed method.