Design Of Low-pass Filter Research Articles

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Analog Building Blocks Optimization for Low-Pass Filter of IEEE 802.11n Wireless LAN: OTA and CCII

The design process of analog circuits is a challenging issue due to the nonidealities. Thus, analog IC design must be automated to shorten the design time and must be optimized to improve the important performance criteria, such as power dissipation, estimated chip occupation area, etc. In this work, a genetic algorithm (GA)-based approach is proposed for the low-pass filter design of IEEE 802.11n Wireless LAN. The performance criteria of OTA and CCII are modeled with an artificial neural network and transistor sizes of those blocks are determined with GA to improve the performance and to satisfy the constraints. The advantage of the proposed methodology is to eliminate infeasible solutions before starting circuit design by modeling the design constraints according to the transistor sizes allowed by production technology. The performance of the proposed method is tested with 0.18- $\mu \text{m}$ technology in CADENCE environment.

Design of microwave lowpass filter based on log periodic zigzag DGS

Abstract This contribution presents, for the first time, the design of microwave lowpass filter with ultrawide stopband and low insertion loss based on the log-periodic zig-zag defected ground structure (DGS); the design is specifically evolved from the principle of the log-periodic line antenna and the slotline based DGS. Based on the log-periodic property, studies show that ultra-wideband suppression can be realized by increasing the flare angle or the angle subtended by each element of the slotline DGS. The developed filter therefore shows low insertion loss of 0.7 dB within the passband, sharp transition between the passband and the stopband and ultra-wide suppression band from 2.61-26.5 GHz with a 20 dB suppression level. The DGS architecture is simple and easy to realize, and the design is thus useful in many microwave applications. The fabricated prototype filter validates the study, both from simulations and from measurements.

A graphene‐metamaterial hybrid structure for the design of reconfigurable low pass terahertz filters

AbstractA graphene‐metamaterial hybrid structure for the design of reconfigurable low pass filters in terahertz region is proposed. This design manages to manipulate the resonance characteristics of metamaterial and terahertz wave response characteristics of the hybrid structure by controlling the chemical potential of graphene. The shift of the resonant frequency and the modulation of the resonant peak of the metamaterial, which have negative effects on the performance of the proposed filter, were studied and the thickness of the dielectric layer between graphene and metamaterial is found to play an important role. Finally, a reconfigurable pass band with a maximum modulation depth of ~ 32% at 0.1THz is obtained.

Design of wide stopband lowpass filter using transformed radial stub based on substrate integrated suspended line technology

AbstractA novel planar elliptic function lowpass filter (LPF) based on substrate integrated suspended line technology is developed and investigated. Transformed radial stub, stepped‐impedance resonators, and open stubs are cascaded to obtain sharp roll‐off and wide stopband. The proposed LPF produces six transmission zeros in the stopband, and the mechanism of the transmission zeros is studied. Both the simulation and measurement are conducted to verify the performance of the proposed filter, and good agreement between the simulated and measured results is observed. The filter shows attractive characteristics such as low insertion loss<0.6 dB, high return loss of 20 dB, wide stopband from 3.85 to 24 GHz with −20 dB attenuation level and a small area of 0.20 λg × 0.14 λg, where λg is the waveguide length at the cutoff frequency.

Harnessing Hardware Defects for Improving Wireless Link Performance

The design trade-offs of transceiver hardware are crucial to the performance of wireless systems. In this paper, we present an in-depth study to characterize the surprisingly notable systemic impacts of low-pass filter (LPF) design, which is a small yet indispensable component used for shaping spectrum and rejecting interference. Using a bottom-up approach, we examine how signal-level distortions caused by the trade-off of LPF design propagate to the upper-layers of wireless communication, reshaping bit error patterns and degrading link performance of today’s 802.11 systems. Moreover, we propose a novel algorithm that harnesses LPF defects for improving video streaming, which substantially enhances video quality in mobile environments.

Mesh low-pass filters for millimeter-wave applications: is the square capacitive shape optimal?

The use of mesh filters for millimeter-wave applications using capacitive and inductive grids is well known, and they are widely used in cosmic microwave background instrumentation. We report on an investigation into whether the capacitive square shape typically used in low-pass filter designs could be improved. The microgenetic algorithm and the finite-difference time-domain, and electromagnetic modeling method were used to look for shape variations to the standard square shape. Any shape changes discovered were then analyzed to establish which variations had the most effect. We show that improvements found using pixelated patterns evolved by the genetic algorithm were somewhat mixed.

ON DESIGN OF SELF-TUNING ACTIVE FILTERS

In this paper, we present one approach in design of self-tuning all-pass, band-pass, low-pass and notch filters based on phase control loops with voltage-controlled active components and analyze their stability as well. The main idea is to vary signal delay of the filter and in this way to achieve phase correction. The filter phase characteristics are tuned by varying the transconductance of the operational transconductance amplifier or capacitance of an MOS varicap element, which are the constituents of filters. This approach allows us to implement active filters with capacitance values of order of pF, making the complete filter circuit to be amenable for realization in CMOS technology. The phase control loops are characterized by good controllable delay over the full range of phase and frequency regulation, high stability, and short settling (locking) time. The proposed circuits are suitable for implementation as a basic building RF function block, used in phase and frequency regulation, frequency synthesis, clock generation recovery, filtering, selective amplifying etc.

Dual split resonator lowpass filter with ultra‐wide stopband and sharp roll‐off rate

A novel microstrip lowpass filter design using rectangular split-ring resonators with dual splits are designed, analysed, and fabricated with exceptional performance such as ultra-wide stopband and sharp roll-off rate along with its compactness. The symmetrical suppressing cells are also employed to reject higher-order harmonics from the stopband without affecting selectivity. The expression for transmission zero of dual split resonator-1 is extracted from the equivalent circuit analysis and observed the significance of coupling. A sharp roll-off performance of 224 dB/GHz and relative stopband width of 161% are achieved with a cut-off frequency of 2.9 GHz.

A Systematic Approach for the Design of the Digital Low-Pass Filters for Energy Storage Systems in EV Applications

Low-pass filters have been used widely in the supervisory energy management controllers (EMC) for electric vehicle applications. However, there has not been a comprehensive methodology for the selection of their key design characteristics, such as the passband, stopband, and attenuation capabilities. In this article, a novel, step-by-step procedure, for the design of the digital low-pass filters (DLPF) is presented for the EMC. Mathematical models for a generalized battery/supercapacitor (SC) structure are derived for the impedance functions of the system. These impedance functions are used to investigate the behavior of the sources and the converter in the frequency domain. Moreover, using the extracted information from the frequency response curves, the guidelines for design of the DLPF are presented. In addition to the DLPF, a fuzzy logic controller is developed to monitor the state-of-charge (SoC) of the SC bank to ensure its operation in a safe region. The controller is designed and tested for the Urban Dynamometer Driving Schedule, using MATLAB/Simulink. Finally, the theory and simulations are validated using a Typhoon hardware-in-loop real-time emulator.

New design of an adjustable compact microstrip lowpass filter using Z‐shaped resonators with low VSWR

AbstractIn this article, an adjustable microstrip lowpass filter(LPF) with the cut‐off frequency (fc) at 1.59 GHz is designed and fabricated. The proposed structure is composed of a Z‐shaped resonator as basic resonator and a combination of modified T‐shaped and Z‐shaped resonators as suppressor units. To describe a theoretical design, the L‐C equivalent circuit of the basic resonator and also its transfer function are calculated precisely; then, the location of the first transmission zero (TZ) is accurately computed. Generating a deep TZ near the cutoff frequency leads to a high roll‐off rate of 195 dB/GH. The LPF also benefits from an extremely wide stopband from 1.72 to 23.67 GHz (15 fc). In passband region, the insertion loss and return loss of the LPF are 0.62 and 22.9 dB, respectively. The experimental results also show that maximum variation of group delay is only 0.53 ns regarding a negligible figure. The electrical size of the LPF is 0.187 × 0.083 (where λg is the guided wavelength at 1.59 GHz). Finally, the proposed LPF achieves a high figure of merit of 57 860 deemed a great accomplishment.

Design of high-performance microstrip and coplanar low-pass filters based on electromagnetic bandgap (EBG) structures

In this paper, a rigorous method for the design of high-performance n-order Chebyshev low-pass filters based on electromagnetic bandgap (EBG) stepped impedances in microstrip and coplanar (CPW) technologies is proposed. Fifth-order low-pass filters implemented by means of circular patterns etched in the ground plane of microstrip and CPW lines have been designed, simulated and measured on an RO3010 substrate (∊r= 10.2, tanδ = 0.0023 at 10 GHz, substrate thickness h = 0.635 mm and copper thickness t = 0.018 mm). The designed filters have shown a good agreement between EM simulation and measurement results. The proposed EBG-based low pass filters, with six etched circles and a size of 42 × 20 mm2, achieve a passband with a cut-off frequency fc = 6 GHz measured at |S11| = −20 dB, return loss RL = 20 dB, 5 reflection zeros in the frequency axis, a ripple lower than 1.1 dB, and a stopband greater than 5 GHz with a rejection level higher than 30 dB. Therefore, the designed low-pass filters have an ultra-wide passband with high return loss, low insertion losses and a low ripple. In addition, they exhibit a large stopband with high rejection level compared to other reported wide stop-band low-pass filters based on EBG, defected ground structures (DGS), or modified complementary split ring resonators (CSRR). This technique can be used to design high-performance Chebyshev EBG-based low-pass filters with a high degree of control over the characteristics of their frequency responses. This allows to replace the EBG-, DGS- and CSRR-based wide stop-band low-pass filters in microwave circuit and antenna applications, with filter structures exhibiting high return loss, equiripple responses in the passband, and high rejection level in the stopband.

Design of optimal low-pass filter by a new Levy swallow swarm algorithm

The swallow swarm optimization (SS) is a challenging method of optimization, which has a quicker convergence speed, not getting caught in the local extreme points. However, the SS suffers from a few shortcomings—(1) the movement speed of particles is not controlled suitably during the search due to the requirement of an inertia weight and (2) the less flexibility of variables does not permit to maintain a balance between the local and the global searches. To solve these problems, a new Levy swallow swarm optimization (SSLY) algorithm with the exploitation capability is proposed. This article also provides an optimal design methodology for the low-pass filter using the suggested SSLY technique. A new objective function is introduced to achieve the maximally flat frequency response, which is another important contribution to the field. The firefly algorithm (FA), the sine cosine algorithm (SCA) and the standard global optimizers—real coded genetic algorithm (GA), conventional particle swarm optimization (PSO), cuckoo search (CS) and SS, are considered for a comparison. The proposed SSLY outperforms the FA, SCA, GA, PSO, CS and SS algorithms. Results authenticate suitability of the proposed algorithm for solving the filter design problems in the FIR domain.

The design of multiple feedback topology Chebyshev low-pass active filter with average differential evolution algorithm

This study presents the design of a tenth-order multiple feedback Chebyshev low-pass filter (MF-C-LPF). Component selection and gain calculation of filters are generally achieved over long periods of time using traditional methods. For 1-dB and 3-dB gains, the component values of the filter were optimized for both continuous and discrete values using four different metaheuristic algorithms. In the first case where continuous values were used, component values were accepted as ideal and unlimited in order to minimize gains. In the second case, industrial E196 series component values were used to transform the design problem into a discrete optimization problem. In this case where the design problem became more complex, the performance of the metaheuristic algorithms was compared. The literature review shows that this study is the first attempt to design a 10th-order MF-C-LPF for E196 series values. The average differential evolution algorithm is proposed to determine the optimal component values of the tenth-order MF-C-LPF. The performance of the proposed method was compared with three commonly used algorithms (PSO, CSS and DE). The optimal filter component values and quality factors (Q) were presented for each stage. We believe that the quality factor values will be a reference for future studies.

Minimization of SIDELOBE Attenuation and Power of a Fir Low Pass Filter using FRFT and CSD Algorithm

For digital signal processing, communication systems and VLSI design architectures, an efficient FIR filter is required to eliminate the noise signals. To design an efficient FIR filter, the minimization of two parameters is required such as side lobe attenuation and power. These two parameters can be achieved by designing a FIR filter with the help of Fractional Fourier Transform (FrFT) and Canonical Signed digit (CSD) algorithm. In this work, Finite Impulse Response (FIR) low pass filter is designed by using both FrFT and ordinary Fourier Transform (FT) methods and their frequency responses are compared in terms of side lobe attenuation (SLA). After comparison of both methods, the better results are obtained for an FrFT based design of FIR low pass filter. Apart from this, the FrFT based design of FIR low pass filter is realized in direct form architecture and implemented in VLSI. Further, the Canonical Signed digit (CSD) algorithm is applied for the multiplication process in the architecture implementation to minimize the power consumption. Moreover, frequency response of FIR low pass filter is obtained by using MATLAB software and simulation and synthesis results are obtained by using Xilinx 13.1 ISE.

A new design approach for nearly linear phase stable IIR filter using fractional derivative

In this paper, a new design method for digital infinite impulse response &#x0028 IIR &#x0029 filters with nearly linear-phase response is presented using fractional derivative constraints &#x0028 FDCs &#x0029 . In the proposed method, design problem of an IIR filter is constructed as the minimization of phase error between the desired and designed phase response of an allpass filter &#x0028 APF &#x0029 such that the designed lowpass filter &#x0028 LPF &#x0029 or highpass filter &#x0028 HPF &#x0029 yields less passband &#x0028 ep &#x0029 , and stopband errors &#x0028 es &#x0029 with optimal stopband attenuation &#x0028 As &#x0029 . In order to have accurate passband &#x0028 pb &#x0029 response, FDCs are imposed on appropriate reference frequency, where the optimality of these FDCs are ensured by using a new greedy based sorting mechanism. The simulated results reflect the efficiency of the proposed method in term of improved passband response along with better transition width. However, small reduction in As is observed within the allowable limit, when compared to non-fractional design approach, but the designed filter remains immune to wordlength &#x0028 WL &#x0029 effect.

Image Denoising with Adaptive Weighted Graph Filtering

Graph filtering, which is founded on the theory of graph signal processing, is proved as a useful tool for image denoising. Most graph filtering methods focus on learning an ideal lowpass filter to remove noise, where clean images are restored from noisy ones by retaining the image components in low graph frequency bands. However, this lowpass filter has limited ability to separate the low-frequency noise from clean images such that it makes the denoising procedure less effective. To address this issue, we propose an adaptive weighted graph filtering (AWGF) method to replace the design of traditional ideal lowpass filter. In detail, we reassess the existing low-rank denoising method with adaptive regularizer learning (ARLLR) from the view of graph filtering. A shrinkage approach subsequently is presented on the graph frequency domain, where the components of noisy image are adaptively decreased in each band by calculating their component significances. As a result, it makes the proposed graph filtering more explainable and suitable for denoising. Meanwhile, we demonstrate a graph filter under the constraint of subspace representation is employed in the ARLLR method. Therefore, ARLLR can be treated as a special form of graph filtering. It not only enriches the theory of graph filtering, but also builds a bridge from the low-rank methods to the graph filtering methods. In the experiments, we perform the AWGF method with a graph filter generated by the classical graph Laplacian matrix. The results show our method can achieve a comparable denoising performance with several state-of-the-art denoising methods.

Simultaneous Design of Low-Pass Filter with Impedance Matching Transformer for SONAR Transducer Using Particle Swarm Optimization

Sound navigation and ranging (SONAR) systems detect a target in the front direction by using acoustic signals. A switching-type power conversion system is used to improve power efficiency, and an impedance matching circuit is used to decrease reactive power. A low-pass filter is used to improve the quality of acoustic signals. To achieve the desired voltage level for a SONAR transducer, a transformer is connected in series with a low-pass filter. In conventional design methods, design value errors occur because the components are designed independently and later combined. Moreover, if parameters that considerably impact operating characteristics are ignored in the design process, these errors will increase. Hence, time and cost losses are incurred during refabrication because operational characteristics differ from design values. To solve this problem, this study proposes the simultaneous design of a low-pass filter and impedance matching circuit, which includes critical design parameters, utilizing the particle swarm optimization algorithm. Moreover, conventional design methods were examined, and the superiority of the proposed design method to conventional methods was verified through analyses and experiments in terms of overall impedance phase and filter blocking characteristics.

Series Optimized Fractional Order Low Pass Butterworth Filter

The design and realization of fractional-order low-pass Butterworth filter (FOLPBF) for order (1 + α), with 0 < α < 1, optimized using a speed enhanced series combination of two meta-heuristic algorithms, namely cuckoo search algorithm (CSA) and interior search algorithm (ISA), is presented in this paper. This method optimizes both the gain and phase for the FOLPBF with respect to the ideal second-order Butterworth filter. The improvement in CSA → ISA series algorithm is established over standalone optimization using CSA and ISA on the basis of gain error, roll-off error, 3 dB frequency error, magnitude error [including passband error (PE) and stopband error (SE)], phase error, and convergence rate. The performance of the series optimization is demonstrated to be superior to the optimization techniques used in previous literature in terms of roll-off error, 3 dB frequency error, PE, SE, phase error and speed. The transient responses achieved with CSA → ISA series optimization is compared with the ideal response using Simulink simulations.

Design and Analysis of Microstrip Low Pass and Bandstop Filters

In this paper a simple approach of designing the microstrip low pass and bandstop filter is presented. The microstrip stub based low pass filter with 2.4 GHz and attenuation of more than 60 dB at 4 GHz frequency is designed. The bandstop filter is also designed with notch characteristics at 2.4 GHz frequency. The fractional bandwidth of designed filter is estimated to be 30% with 117 dB of attenuation is recorded at notch frequency of 2.4 GHz in SIR based bandstop filter topology. The bandstop filter is implemented using coupled line structure as well as step impedance resonator techniques. The filters are designed on Roger RC40003C substrate. The design and analysis of filter with its layout and EM simulation is accomplished using Agilent ADS software. These filters can be used in front end transceiver systems, antennas, and modern wireless communication systems.