Journal articles: 'Controlled frequency filter'

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Lan, Qiao Qian, Min Hui Xu, and Wei Jian Jin. "Design of High Frequency Program-Controlled Filter." Applied Mechanics and Materials 226-228 (November 2012): 2480–83. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.2480.

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In order to meet the requirements of most controllable filters of the high frequency of the system , this paper introduces a kind of programmable filter designing based on MAX262, and discuss the method of realizing , in the case of full comprehending the theory of filers, using Multisim to simulate. Analysing the simulation results of the output, it shows that this scheme of filter designing is good, the center frequency and the storage factor Q can be programmed to control ,in order to apply to varieties of frequency band filtering in signal detection.

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Abdolvand, Reza, and Farrokh Ayazi. "High-frequency monolithic thin-film piezoelectric-on-substrate filters." International Journal of Microwave and Wireless Technologies 1, no. 1 (February 2009): 29–35. http://dx.doi.org/10.1017/s175907870900004x.

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A class of micromachined acoustic filters is presented in which the number of individual resonant structures is reduced to 1 (monolithic filter). This resonant structure is comprised of a stack of thin-film piezoelectric-on-silicon. Symmetric and anti-symmetric resonance modes (dual modes) of the silicon structure are piezoelectrically excited and coupled to realize a 2-pole narrowband filter. High-order lateral bulk acoustic resonance modes of a rectangular plate are utilized to design dispersed-frequency UHF filters fabricated on a single substrate. Thickness mode filters are also realized at GHz frequencies using a new interdigitated electrode design. Additionally, it is shown that the filter bandwidth can be controlled by changing the dimensions of the resonant structure and the electrode pattern. Narrowband lateral mode filters with filter Q’s larger than 300 at ~440 MHz and thickness mode filters with filter Q’s in the range of 150–900 at ~3.1 GHz are demonstrated.

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Naydenov, Borislav Georgiev, Antim Hristov Yordanov, and Lyubomir Petrov Kamburov. "Mathematical model of parametrically controlled matched filters." ANNUAL JOURNAL OF TECHNICAL UNIVERSITY OF VARNA, BULGARIA 1, no. 1 (December 28, 2017): 27–31. http://dx.doi.org/10.29114/ajtuv.vol1.iss1.60.

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A one model of parametrically controlled coherent filters is described and analyzed, applied also in radar systems and mobile communication systems to improve noise resistance. Application of the Nyquist-Shannon theorem in the frequency domain to obtain a set of frequency filters with variable parameters. The conversion of the signal at the output of the parameter filter using the auto correlation feature is shown when a normal white noise occurs.

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Joelianto, Endra. "On Minimal Second-order IIR Bandpass Filters with Constrained Poles and Zeros." Journal of Engineering and Technological Sciences 53, no. 4 (August 3, 2021): 210401. http://dx.doi.org/10.5614/j.eng.technol.sci.2021.53.4.1.

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In this paper, several forms of infinite impulse response (IIR) bandpass filters with constrained poles and zeros are presented and compared. The comparison includes the filter structure, the frequency ranges and a number of controlled parameters that affect computational efforts. Using the relationship between bandpass and notch filters, the two presented filters were originally developed for notch filters. This paper also proposes a second-order IIR bandpass filter structure that constrains poles and zeros and can be used as a minimal parameter adaptive digital second-order filter. The proposed filter has a wider frequency range and more flexibility in the range values of the adaptation parameters.

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Ma, Sheng Qian, Chang Rong Zhao, and Yan Ping Ji. "HF Voltage-Controllable Band-Pass Filter Based on Varactor." Applied Mechanics and Materials 631-632 (September 2014): 327–32. http://dx.doi.org/10.4028/www.scientific.net/amm.631-632.327.

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Varactor to replace commonly variable capacitance is applied to the tuner. This paper presents the voltage-controllable band-pass filter design method. The filter constitutes of operational amplifier, resistors, varactor MV209 and parallel LC resonant circuit. Center frequency range of the band-pass filters is from 19MHz to 25MHz controlled with DC voltage. It derives the transfer function of the filter and function expression of junction capacitance with reverse voltage. The frequency response of filter simulation and experimental results are given. Key words: Varactor; Band-Pass Filter; Voltage-Controllable Filter; Junction Capacitance

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Gan, Huijun, Dongsheng Yu, Dongkun Li, and He Cheng. "Binary memcapacitor based first-order active filter." Circuit World 46, no. 2 (January 10, 2020): 117–24. http://dx.doi.org/10.1108/cw-06-2019-0061.

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Purpose The purpose of this paper is to construct a flux-controlled memcapacitor (MC) emulator without grounded restriction with the binary operation ability. The active first-order low-pass filter (LPF) and high-pass filter (HPF) circuits are constructed by replacing the capacitor with MC. Design/methodology/approach The output saturation of the active device is innovatively adopted to realize the binary operation of MC with two memcapacitance values. By applying the direct current control voltage together with the input signal, the memcapacitance can be controlled, and hence, cut-off frequency of the filters can be adjusted without changing the circuit structure. Findings Experiments and simulation results show that the new filter has good frequency selectivity. Both LPF and HPF can change the cut-off frequency by changing the positive and negative control voltage. The experimental and simulation results are in good agreement with the theoretical analysis, which proves the feasibility and validity of the emulator and the filters. Originality/value These MC emulators are simple and easy to physically fabricate, which have been increasingly used for experiment. It also provide an effective reference for device miniaturization and low power consumption.

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Ma, Sheng Qian, Yan Ping Ji, Xing Ping Ran, Wei Zhao Zhang, and Yang Yang. "Design of the Voltage-Controlled Bandpass Filter Based on Current Feedback Op Amp." Advanced Materials Research 986-987 (July 2014): 1081–85. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1081.

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This paper puts forward structure and realization method of the voltage-controlled band-pass filter based on the current feedback operational amplifier (CFA) which uses bi-quad loop filter circuit model to design the new filter circuit. Input voltage signal is input to voltage-controlled band-pass filter circuit composed by an analog multiplier AD835 and a current feedback operational amplifier AD8001 which are the core. Using the voltage signal to adjust the center frequency of the filter, the filter has wide frequency band and good high-frequency performance. This paper describes the design principles, infers the design formulas and designs the circuit of the voltage-controlled first-order and second-order band-pass filter.Through the simulation, the filter can realize the scope of the center frequency from 200KHz to 10MHz.

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Azad, Amit Ranjan, and Akhilesh Mohan. "Compact bandpass filter with wide-stopband using substrate integrated waveguide cavities and short-circuited coplanar line." International Journal of Microwave and Wireless Technologies 12, no. 5 (November 26, 2019): 345–51. http://dx.doi.org/10.1017/s175907871900148x.

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AbstractThis article presented a compact bandpass filter with wide-stopband performance. Two substrate integrated waveguide (SIW) cavities and a short-circuited coplanar line introduced between the two cavities are used to realize a compact third-order bandpass filter. The passband is generated by combining the resonant frequency of TE101 mode of the SIW cavities and the fundamental resonant frequency of the short-circuited coplanar line. The size of the proposed filter reduces significantly in comparison with conventional third-order SIW filters. Moreover, the center frequency (CF) and the bandwidth of the filter can be controlled by adjusting the structural parameters of the filter. In addition, the first higher-order mode TE102 of the SIW cavity is suppressed by minimizing the coupling of TE102 mode in order to obtain wide-stopband performance. The proposed filter is designed, fabricated, and measured, and the simulation and measurement results show a good agreement. The filter exhibits compact size, low loss, and a rejection higher than 20 dB up to 1.94f0.

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Górski, Paweł, and Leszek Morzyński. "Active Noise Reduction Algorithm Based on NOTCH Filter and Genetic Algorithm." Archives of Acoustics 38, no. 2 (June 1, 2013): 185–90. http://dx.doi.org/10.2478/aoa-2013-0021.

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Abstract Application of active noise reduction (ANR) systems in hearing protectors requires the use of control algorithms to ensure stability of the ANR system and at the same time highly effective active noise reduction. A control algorithm based on NOTCH filters is an example of solutions that meet these criteria. Their disadvantage is operation over a narrow frequency band and a need for prior determination of frequencies to be reduced. This paper presents a solution of the ANR system for hearing protectors which is controlled with the use of modified NOTCH filters with parameters determined by a genetic algorithm. Application of a genetic algorithm allows to change the NOTCH filter reference signal frequency, and thus, adapt the filter to the reduced signal frequency.

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Mitić, Darko, Goran Jovanović, Mile Stojčev, and Dragan Antić. "ON DESIGN OF SELF-TUNING ACTIVE FILTERS." Facta Universitatis, Series: Automatic Control and Robotics 19, no. 1 (July 28, 2020): 059. http://dx.doi.org/10.22190/fuacr2001059m.

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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.

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Li, Luping, Lijuan Dong, Peng Chen, and Kai Yang. "Multi-band rejection filters based on spoof surface plasmon polaritons and folded split-ring resonators." International Journal of Microwave and Wireless Technologies 11, no. 08 (April 17, 2019): 774–81. http://dx.doi.org/10.1017/s1759078719000369.

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AbstractA dualband rejection filter and a triband rejection filter are proposed in this letter, both of which are implemented by cascading spoof surface plasmon polaritons (SSPPs) of the same structure but with diverse rejection bands. Compared with traditional ones, the proposed filters provide more compact structures, wider rejection bands, and better independent tunability. In the proposed filters, the rejection bandwidth, the center frequency of the rejection band and the filter's cutoff frequency can be adjusted independently. And the different rejection bands in the same filter also can be independently controlled. Agreements between the dispersion of SSPP units and the S21 of filters are also presented. Measurement results demonstrate that both filters load multiple rejection bands on the 27.7 GHz wide low-pass band and all the rejection bands locate in Ku and K bands. The average rejection bandwidth and the average rejection depth of the two filters are 1.49 GHz and 42.1 dB, respectively.

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12

Zhou, Wen‐Jun, and Jian‐Xin Chen. "Novel microfluidically tunable bandpass filter with precisely‐controlled passband frequency." Electronics Letters 52, no. 14 (July 2016): 1235–36. http://dx.doi.org/10.1049/el.2016.1298.

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13

Pendharker, Sarang, Raghunath K. Shevgaonkar, and Arun N. Chandorkar. "Optically controlled frequency reconfigurable band stop filter with multifrequency switching." Microwave and Optical Technology Letters 56, no. 5 (March 11, 2014): 1204–11. http://dx.doi.org/10.1002/mop.28297.

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Chen, Shinn-Horng, Jyh-Horng Chou, and Liang-An Zheng. "Robust Kalman-Filter-Based Frequency-Shaping Optimal Active Vibration Control of Uncertain Flexible Mechanical Systems." Journal of Mechanics 16, no. 3 (September 2000): 145–55. http://dx.doi.org/10.1017/s1727719100001805.

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ABSTRACTThis paper presents a time-domain control methodology, which is named as the robust Kalman-filter-based frequency-shaping optimal feedback (KFBFSOF) control method, to treat the active vibration control (or active vibration suppression) problem of flexible mechanical systems under simultaneously high frequencies unmodelled dynamics, residual modes, linear time-varying parameter perturbations in both the controlled and residual parts, noises (input noise and measurement noise),and noise uncertainties. Two robust stability conditions are proposed for the flexible mechanical system, which is controlled by a KFBFSOF controller and subject to mode truncation, noise uncertainties, and linear structured time-varying parameter perturbations simultaneously. The advantage of the presented KFBFSOF control methodology is that it can make the controlled closed-loop system to obtain both good robustness at high frequencies and good performance at low frequencies. Besides, the proposed robust stability criteria guarantee that the designed KFBFSOF controller can make the controlled flexible mechanical system to avoid the possibilities of both spillover-induced instability and time-varying-parameter-perturbation-induced instability. Two examples are given to illustrate the application of the presented control methodology to the active vibration control problems of a simply supported flexible beam and of a flexible rotor system.

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Werthmüller, Dieter, Kerry Key, and Evert C. Slob. "A tool for designing digital filters for the Hankel and Fourier transforms in potential, diffusive, and wavefield modeling." GEOPHYSICS 84, no. 2 (March 1, 2019): F47—F56. http://dx.doi.org/10.1190/geo2018-0069.1.

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The open-source code fdesign makes it possible to design digital linear filters for the Hankel and Fourier transforms used in potential, diffusive, and wavefield modeling. Digital filters can be derived for any electromagnetic (EM) method, such as methods in the diffusive limits (direct current, controlled-source EM [CSEM]) as well as methods using higher frequency content (ground-penetrating radar [GPR], acoustic and elastic wavefields). The direct matrix inversion method is used for the derivation of the filter values, and a brute-force minimization search is carried out over the defined spacing and shifting values of the filter basis. Included or user-provided theoretical transform pairs are used for the inversion. Alternatively, one can provide layered subsurface models that will be computed with a precise quadrature method using the EM modeler empymod to generate numerical transform pairs. The comparison of the presented 201 pt filter with previously presented filters indicates that it performs better for some standard CSEM cases. The derivation of a longer 2001 pt filter for a GPR example with a 250 MHz center frequency proves that the filter method works not only for diffusive EM fields but also for wave phenomena. The presented algorithm provides a tool to create problem specific digital filters. Such purpose-built filters can be made shorter and can speed up consecutive potential, diffusive, and wavefield inversions.

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Lu, Xiaoming, Koen Mouthaan, and Tat Soon Yeo. "A Wideband Bandpass Filter With Frequency Selectivity Controlled by SAW Resonators." IEEE Transactions on Components, Packaging and Manufacturing Technology 6, no. 6 (June 2016): 897–905. http://dx.doi.org/10.1109/tcpmt.2016.2553105.

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Sooksatra, S., and C. Q. Lee. "PWM-controlled SRC with inductive output filter at constant switching frequency." IEEE Transactions on Power Electronics 7, no. 2 (April 1992): 289–95. http://dx.doi.org/10.1109/63.136245.

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Chinnappan, Ravichandran, Premalatha Logamani, and Rengaraj Ramasubbu. "Fixed- and variable-frequency sliding mode controller–maximum power point tracking converter for two-stage grid-integrated photovoltaic system employing nonlinear loads with power quality improvement features." Measurement and Control 52, no. 7-8 (May 13, 2019): 896–912. http://dx.doi.org/10.1177/0020294019830120.

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This article presents a reliable and efficient photovoltaic sliding mode voltage-controlled maximum power point tracking DC-DC converter–active power filter integration system to supply real power to grid. This integrated active power filter system performs power quality enhancement features to compensate current harmonics to make distortion-free grid supply current and reactive power employing nonlinear loads. The proposed proportional–integral–derivative–based sliding mode controller is designed with fixed-frequency pulse-width modulation based on equivalent control approach. The main objective of this paper is to design a photovoltaic system with a new sliding surface to force the photovoltaic voltage to follow the reference maximum power point voltage with the alleviation of slow transient response and disadvantages of chattering effects of variable-frequency hysteresis modulation sliding mode controller–maximum power point tracking. The perturbations caused by the uncertainties in climatic conditions and converter output bulk oscillations during grid integration are also mitigated. The features of the proposed photovoltaic–active power filter integration system are confirmed at different operating conditions through PSIM simulation software, and its performance is also compared with a conventional variable-frequency sliding mode-controlled maximum power point tracking. The obtained simulation and experimental results give good dynamic response under various operating conditions of environmental and local load conditions.

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Silva, L. G., A. A. C. Alves, and Arismar Cerqueira Sodré. "Optically Controlled Reconfigurable Filtenna." International Journal of Antennas and Propagation 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/7161070.

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This work is regarding the development of a novel antenna called optically controlled reconfigurable filtenna, which is based on the integration of a broadband printed antenna with a bandpass reconfigurable RF filter. The filter is designed by applying defected microstrip structure (DMS) technique and positioned in printed antenna feeding line in order to keep the same size of the original antenna. The filtenna bandwidth is optically reconfigurable by using two photoconductive silicon switches excited by CW laser at 808 nm. Numerical results rely on independent and switchable operational modes through the 2.4 and 5.1 GHz ISM bands, whereas measurements demonstrate two reconfigurable modes based on single-band/dual-band operation over the same frequency bands. The proposed device is validated by theoretical, numerical, and experimental results.

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Wang, Ji Dong, and Mei Cui Qin. "Microgrid Harmonic Suppression Method Based on One Cycle Controlled Active Power Filter." Applied Mechanics and Materials 347-350 (August 2013): 1445–49. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1445.

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With widely research and application of microgrid, the effect of the harmonic problems becomes not be ignored. This paper applies one cycle controlled active power filter (APF) to suppress harmonic in microgrid. Compared with traditional methods, one cycle controlled APF omits the harmonic detecting circuit and greatly simplifies the system structure. The one cycle control method in this paper, combining with space vector control, divides the frequency cycle into three control sextants, which simplifies the controller further. This paper builds the model of one cycle controlled APF and microgrid model including wind power system and photovoltaic systems. Then make simulation analysis about microgrid harmonic suppression. Simulation results show that one cycle controlled APF has a good compensation effect in microgrid harmonic suppression.

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Alraho, Senan, Qummar Zaman, and Andreas König. "Wide Programmable Range Fourth-Order, Fully-Differential Sallen-Key MOSFET-C LPF for Impedance Spectroscopy Measurements and Self-X Sensory Electronics in Industry 4.0." tm - Technisches Messen 88, s1 (August 24, 2021): s77—s82. http://dx.doi.org/10.1515/teme-2021-0064.

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Abstract This paper picks up the need for a wide range programmable corner frequency for anti-aliasing and antiimaging filters in on-chip impedance spectroscopy and sensor signal readout circuitry with self-X properties (selfdiagnosing/healing) for industry 4.0 applications. A fourthorder wide tunable range MOSFET-C low pass filter is designed by using XFAB 0.35 μm CMOS technology and Cadence design tools. The proposed circuit is based on fully differential Sallen-Key architecture with Butterworth approximation. It covers a frequency range from 30 Hz up to 7 MHz. Tunability is achieved using a potentially high resistance and linearized configurable MOS resistor to control the filter pole frequency. The configurable elements in the circuit serve as tuning knobs to be controlled by machine learning. The physical design area is 0.39mm2.

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Pinto, Marinaldo F., Dinara G. Alves, Ezequiel Saretta, Antonio P. de Camargo, and Tarlei A. Botrel. "Development of a filtration system with high-frequency flow reversal." Revista Brasileira de Engenharia Agrícola e Ambiental 20, no. 4 (April 2016): 295–301. http://dx.doi.org/10.1590/1807-1929/agriambi.v20n4p295-301.

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ABSTRACT The aim of this study was to develop a filtration system with high-frequency flow reversal and minimum requirement of water for cleaning routines. The system was developed in the period from 2011 to 2013 and consists of three screen filters and eleven solenoid valves electronically controlled by a controller that operates based on head loss measurements. The following evaluations were carried out: head loss curve as a function of flow rate; filtrating efficiency as a function of solids concentration, frequency of flow reversal and increment in head loss. The experimental design was completely randomized in a factorial scheme with three replicates and two treatment levels for each factor. The filtration efficiency was equal to 98.6% for particles larger than 50 µm. The minimum volume of water for each cleaning of the filters was 5.39 L. The head loss increment in the filtration system with flow reversal at frequencies of 11.11 and 22.22 mHz was smaller compared with the filtration system without flow reversal. The developed filtration system has potential for filtering low-quality irrigation water, but requires periodic maintenance to clean the filter element.

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Rahimi, Eesa, and Kürşat Şendur. "Thermally controlled femtosecond pulse shaping using metasurface based optical filters." Nanophotonics 7, no. 3 (February 23, 2018): 659–68. http://dx.doi.org/10.1515/nanoph-2017-0089.

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AbstractShaping of the temporal distribution of the ultrashort pulses, compensation of pulse deformations due to phase shift in transmission and amplification are of interest in various optical applications. To address these problems, in this study, we have demonstrated an ultra-thin reconfigurable localized surface plasmon (LSP) band-stop optical filter driven by insulator-metal phase transition of vanadium dioxide. A Joule heating mechanism is proposed to control the thermal phase transition of the material. The resulting permittivity variation of vanadium dioxide tailors spectral response of the transmitted pulse from the stack. Depending on how the pulse’s spectrum is located with respect to the resonance of the band-stop filter, the thin film stack can dynamically compress/expand the output pulse span up to 20% or shift its phase up to 360°. Multi-stacked filters have shown the ability to dynamically compensate input carrier frequency shifts and pulse span variations besides their higher span expansion rates.

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Jerabek, Jan, Roman Sotner, and Kamil Vrba. "Tiso Adjustable Filter with Controllable Controlled–Gain Voltage Differencing Current Conveyor." Journal of Electrical Engineering 65, no. 3 (May 1, 2014): 137–43. http://dx.doi.org/10.2478/jee-2014-0021.

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Abstract The main aim of this paper is to present solution of triple-input single-output (TISO) filter with independently adjustable pole frequency, quality factor, bandwidth and also gain. Filter is universal, operates in current mode and includes only one active element - the so-called Controlled-Gain Voltage Differencing Current Conveyor (CG-VDCC) with two controllable parameters: transconductance (gm) and gain of output currents (BX ). Implementation of CG-VDCC element in 0.18 μm CMOS technology is also included and this model is used in proposed filter simulations.

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Bang, Jun-Ho, In-Ho Ryu, and Jae-Young Yu. "A Voltage-controlled Frequency Tunable CMOS Current-mode Filter for Software Radio." Transactions of The Korean Institute of Electrical Engineers 60, no. 4 (April 1, 2011): 871–76. http://dx.doi.org/10.5370/kiee.2011.60.4.871.

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Nedungadi, A. P., and R. L. Geiger. "High-frequency voltage-controlled continuous-time lowpass filter using linearised CMOS integrators." Electronics Letters 22, no. 14 (1986): 729. http://dx.doi.org/10.1049/el:19860500.

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Okushima, L., M. Saito, S. Sase, P. Ling, and M. Ishii. "Spectral Characteristics of Penicillium Species using a Frequency controlled Liquid Crystal Filter." Biosystems Engineering 88, no. 3 (July 2004): 265–69. http://dx.doi.org/10.1016/j.biosystemseng.2004.04.001.

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Chen, Shinn-Horng. "Robust Kalman-Filter-Based Frequency-Shaping Optimal Active Vibration Control of Uncertain Flexible Mechanical Systems with Nonlinear Actuators." Journal of Vibration and Control 9, no. 6 (June 2003): 623–44. http://dx.doi.org/10.1177/1077546303009006001.

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In this paper, we present a time-domain control methodology, called the robust Kalman-filter-based frequency-shaping optimal feedback (KFBFSOF) control method. Using this method, we treat the active vibration control (or active vibration suppression) problem of flexible mechanical systems under simultaneously high-frequency unmodeled dynamics, residual modes, linear time-varying parameter perturbations in both the controlled and residual parts, noises (input noise and measurement noise), noise uncertainties and actuator nonlinearities. Two robust stability conditions are proposed for the flexible mechanical system, which is controlled by a KFBFSOF controller and subject to mode truncation, noise uncertainties, actuator nonlinearities and linear structured time-varying parameter perturbations simultaneously. The advantage of the presented KFBFSOF control methodology is that it can make the controlled closed-loop system have both good robustness at high frequencies and good performance at low frequencies. Besides, the proposed robust stability criteria guarantee that the designed KFBFSOF controller can make the controlled flexible mechanical system avoid the possibilities of instability induced by both spillover and time-varying parameter perturbations. Two examples are given to illustrate the application of the presented control methodology to the active vibration control problems of a simply-supported flexible beam and of a flexible rotor system.

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Rashmi, Ruchi, and Shweta Jagtap. "A comparative study of phase margin based digital and analog controlled synchronous buck with optimum LC filter." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 6 (October 24, 2019): 2020–39. http://dx.doi.org/10.1108/compel-12-2018-0508.

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Purpose Traditionally, industrial power supplies have been exclusively controlled through analog control to sustain high reliability with low cost. However, with the perpetual decrement in cost of digital controllers, the feasibility of a digitally controlled switch mode power supply has elevated significantly. This paper aims to outline the challenges related to the design of digital proportional-integral (PI) controlled synchronous rectifier (SR) buck converter by comparing controller performance in continuous and discrete time. The trapezoidal approximation-based digital PI control is designed for low voltage and high-frequency SR buck converter operating under continuous conduction mode. Design/methodology/approach The analog and digital controller are designed using a SISO tool of MATLAB. Here, zero-order hold transform is used to convert the transfer function from continuous to discrete time. Frequency and time domain analysis of continuous plant, discrete plant and close loop system is performed. The designed digital PI control is simulated in MATLAB Simulink. The simulated results is also verified on hardware designed around digital signal processing control. Findings The continuous and discrete control loops are validated with multiple tests in the time and frequency domain. The detailed steady state theoretical analysis and performance of the SR buck converter is presented and verified by simulation. It is found that the delay in digital control loop results in a low phase margin. This phase margin decreases with higher bandwidth. The hardware experiments with the digital control loop are carried out on a 10 W prototype. The chosen parameters for the SR buck converter are found to be optimum for steady and transient state response. Originality/value This paper compares the digital and analog control approach of compensator design. It focuses on the implications created at the time of transforming the control design from continuous to discrete time. Further, it also focuses on the selection of parameters such as phase margin, bandwidth and low pass filter.

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Premalatha, R., and P. Murugesan. "Comparison of Filter with Fuzzy Controlled Three Level DC-DC Converter Fed Drive." International Journal of Engineering Research in Africa 14 (March 2015): 63–74. http://dx.doi.org/10.4028/www.scientific.net/jera.14.63.

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A simple Fuzzy logic controller (FLC) applied to buck converter is presented in this paper. This approach uses FLC which performs better when compared with the conventional PI controllers. In proposed buck converters, high voltage dc supply is switched at very high frequency and inductively transferred to dc load via a high frequency transformer and rectifier. In this converter four power switches are connected in series to primary of high frequency transformer for large load currents. To achieve large step-down voltage ratios the power switches are turned ON and OFF alternatively with a time gap. The voltage step-down ratios, Total Harmonic Distortion and angular velocity of drive are the parameters to be analyzed. The comparison with the original FLC and comparison of three level DC-DC converter with capacitor and pi filter is carried out by MATLAB-Simulink simulation and Model is designed to verify the proposed method performance.

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Wang, San-Fu, Hua-Pin Chen, Yitsen Ku, and Chia-Ling Lee. "Versatile Voltage-Mode Biquadratic Filter and Quadrature Oscillator Using Four OTAs and Two Grounded Capacitors." Electronics 9, no. 9 (September 11, 2020): 1493. http://dx.doi.org/10.3390/electronics9091493.

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This article presents a versatile voltage-mode (VM) biquad filter with independently electronic tunability. The proposed structure using one dual-output operational transconductance amplifier, three single-output operational transconductance amplifiers (OTAs) and two grounded capacitors was explored to derive a new VM quadrature oscillator with the independent control of the oscillation frequency and the oscillation condition. The proposed versatile VM biquad filter achieves nearly all of the main advantages: (i) simultaneous realizations of band-reject, band-pass, and low-pass from the same architecture, (ii) multiple-input and multiple-output functions, (iii) independent electronic adjustability of quality factor and resonant angular frequency, (iv) no resistor needed, (v) all input terminals with cascade functions, (vi) no additional inverting amplifier for input signals, (vii) using only grounded capacitors, and (viii) easy to implement a VM quadrature oscillator with independent electronically controlled oscillation frequency and oscillation condition. The proposed versatile VM biquad filter employs only four OTAs and two grounded capacitors. The active components of the proposed VM biquad filter are one less than that of recent reports. The proposed circuit also brings versatility and simplicity to the design of VM biquad filters and VM quadrature oscillators. Filters and oscillators with less active and passive components have the advantages of low cost, low power dissipation, low circuit complexity, and low noise. Commercially available integrated circuit LT1228 and discrete components can be used to implement the proposed OTA-based circuits. The simulation and experiment results validated the theoretical analysis.

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Aubakirov, Konstantin Ya, and Alexander V. Makeev. "ANALOG PHASE SHIFTERS OF THE DECIMETER RANGE FOR INCREASED POWER LEVEL." Interexpo GEO-Siberia 8, no. 2 (July 8, 2020): 89–93. http://dx.doi.org/10.33764/2618-981x-2020-8-2-89-93.

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The results of designing a phase control device in the decimeter wavelength range in the form of a tunable bandpass filter are presented. Tuning such a filter by 1/2 of the relative bandwidth, not exceeding 40 - 50%, provides a frequency-independent controlled phase shift. The minimization of parasitic amplitude modulation, along with an increase in the high-frequency power transmitted by the phase shifter, is achieved by optimizing the switching factor of the varicap into the quasi-polynomial bandpass filter circuit.

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Jerabek, Jan, Jan Dvorak, Roman Sotner, Norbert Herencsar, and Jaroslav Koton. "Experimental Verification of Pseudo-Differential Electronically Controllable Multifunction Filter Using Modified Current Differencing/Summing Units." Journal of Circuits, Systems and Computers 28, no. 06 (June 12, 2019): 1950098. http://dx.doi.org/10.1142/s0218126619500981.

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This paper presents the synthesis and analysis of reconfigurable frequency filter with differential input and differential output terminals and its experimental verification. The inner structure of the filter has single-ended form, i.e., filter behaves as the so-called pseudo-differential circuit. Filtering function can be electronically reconfigured between low-pass (LP) and band-pass (BP) responses. Active elements of the filter are differential voltage buffer (DVB) as an input stage and modified current differencing unit (MCDU) together with modified current summing unit (MCSU) as the inner and also output stage. Each of the important parameters of the filter (angular pole frequency, quality factor and pass-band gain) is electronically controllable by parameters of these active elements used. Some of the parameters of the filter are controlled by two independent parameters, i.e., are dual-controlled, which enables the extended electronic controllability. The proposed topology operates in the voltage mode and both input nodes have high input impedance. Expected behavior of the filter is analyzed and verified by PSpice simulations using CMOS models of above-mentioned active elements. Moreover, features of the filter in both configurations were successfully verified also by experimental measurements using behavioral models of active elements.

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Menq, Chia-Hsiang, and Jin-jae Chen. "Precision Tracking Control of Discrete Time Nonminimum-Phase Systems." Journal of Dynamic Systems, Measurement, and Control 115, no. 2A (June 1, 1993): 238–45. http://dx.doi.org/10.1115/1.2899027.

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In this paper, a precision tracking control scheme for linear discrete time nonminimum-phase systems is proposed. This control scheme consists of a preview filter, a tracking-performance filter, a command feedforward controller, and a feedback controller. A command feedforward controller, whose design is based on the minimal order inverse model of the plant being controlled, will result in a completely decoupled system. The preview filter is introduced to compensate the phase and gain errors induced by the nonminimum phase zeros or lightly damped zeros of the system. Using the command feedforward controller along with the proposed preview filter, the tracking performance of the proposed control scheme can be characterized by the frequency response of the tracking-performance filter. For the design of the preview filter, a generalized Nth order preview filter and its associated penalty function that quantifies the tracking error of a design are defined. It is shown that, given the desired bandwidth and the order of the preview filter, the optimal solution for the design of the preview filter can be obtained explicitly. The proposed control scheme together with the optimal preview filter is shown to be very effective in achieving precision tracking control of discrete time MIMO nonminimum phase systems. It is also shown that the tracking performance is improved as the order N of the preview filter is increased.

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Mathur, Koushick, Palaniandavar Venkateswaran, and Rabindranath Nandi. "All-Pass Filter Based Linear Voltage Controlled Quadrature Oscillator." Active and Passive Electronic Components 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/3454165.

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A linear voltage controlled quadrature oscillator implemented from a first-order electronically tunable all-pass filter (ETAF) is presented. The active element is commercially available current feedback amplifier (AD844) in conjunction with the relatively new Multiplication Mode Current Conveyor (MMCC) device. Electronic tunability is obtained by the control node voltage (V) of the MMCC. Effects of the device nonidealities, namely, the parasitic capacitors and the roll-off poles of the port-transfer ratios of the device, are shown to be negligible, even though the usable high-frequency ranges are constrained by these imperfections. Subsequently the filter is looped with an electronically tunable integrator (ETI) to implement the quadrature oscillator (QO). Experimental responses on the voltage tunable phase of the filter and the linear-tuning law of the quadrature oscillator up to 9.9 MHz at low THD are verified by simulation and hardware tests.

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Chilipi, Rajasekhara Reddy, Bhim Singh, and Srinivasa Murthy. "A New Voltage and Frequency Controller for Standalone Parallel Operated Self Excited Induction Generators." International Journal of Emerging Electric Power Systems 13, no. 1 (February 18, 2012): 1–17. http://dx.doi.org/10.1515/1553-779x.2809.

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This work proposes a new voltage and frequency controller (VFC) for standalone parallel operated self excited induction generators driven by uncontrolled micro hydro turbines. This VFC consists of a current controlled static compensator (STATCOM) for regulating the voltage during different load conditions and a variable frequency induction motor drive driving a water pump operating as an electronic load controller (ELC) for balancing the generated power, which in turn regulates the system frequency. The STATCOM functions as a reactive power compensator for regulating the system voltage and an active filter for harmonics elimination. The control algorithm of STATCOM is based on the synchronous reference frame (SRF) theory.

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Langhammer, Lukas, Jan Dvorak, Jan Jerabek, Jaroslav Koton, and Roman Sotner. "Fractional-order low-pass filter with electronic tunability of its order and pole frequency." Journal of Electrical Engineering 69, no. 1 (January 1, 2018): 3–13. http://dx.doi.org/10.1515/jee-2018-0001.

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Abstract This paper presents novel solution of a fractional-order low-pass filter (FLPF). The proposed filter operates in the current mode and it is designed using third-order inverse follow-the-leader feedback topology and operational transconductance amplifiers (OTAs), adjustable current amplifiers (ACAs), auxiliary multiple-output current follower (MO-CF) as simple active elements. The filter offers the beneficial ability of the electronic control of its order and also the pole frequency thanks to electronically controlled internal parameters of OTAs and ACAs. As an example, five particular values of fractional order of the FLPF were chosen and parameters of the filter were calculated. Similarly, also electronic control of the pole frequency of the filter was studied. The design correctness and proper function of the filter are supported by simulations with CMOS models and also by experimental laboratory measurements. Comparison of the simulation results of the proposed filter for two different approximations of the parameter sα is also included.

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Lee, Sang-Ho, Hobyung Yoon, Jungje Ha, and Yongshik Lee. "Wideband suppression of spurious response for microstrip filters based on coupled lines of incommensurate lengths." International Journal of Microwave and Wireless Technologies 7, no. 6 (August 13, 2014): 685–90. http://dx.doi.org/10.1017/s1759078714001056.

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This work demonstrates design methods that can achieve remarkable enhancement in the stopband response of microstrip coupled-line filters. The frequencies of resonance and/or the transmission zeros of a coupled-line section can be controlled by its length. Therefore, by constructing a filter with coupled lines of incommensurate lengths such that these frequencies do not overlap, substantial improvement in the stopband response can be obtained. Besides its compact structure and simple design procedure, an unprecedented performance is demonstrated experimentally in which the transmission level is maintained below −20 dB up to as high as 11.9 f0 for a third-order filter, where f0 is the center frequency.

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Summart, Saksit, and Chanchai Thongsopa. "CDTAs Based Current-Mode Universal Biquad Filters with Orthogonal Control of Quality Factor and Pole Frequency." Advanced Materials Research 787 (September 2013): 501–7. http://dx.doi.org/10.4028/www.scientific.net/amr.787.501.

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This article presents current-mode universal biquad filters based on CDTAs. The filter circuits using four CDTAs and two grounded capacitors which are able to provide low-pass, high-pass, band-pass, band-reject and all-pass functions. The pole frequency can be orthogonally controlled from quality factor and the circuits have high output impedance appropriate for cascade connection application in current mode which is capable to directly drive load. This qualification is very appropriate for further development into an integrated circuit. The results of PSPICE simulation program are corresponding to the theoretical analysis.

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MAHESHWARI, SUDHANSHU. "A NEW CURRENT-MODE CURRENT-CONTROLLED ALL-PASS SECTION." Journal of Circuits, Systems and Computers 16, no. 02 (April 2007): 181–89. http://dx.doi.org/10.1142/s0218126607003599.

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This paper presents a new translinear-C current-mode first order all-pass filter suited for high frequency operation. The new circuit offers a simpler structure than the available translinear-C works. The pole-frequency of the circuit is controllable over a wide range through external bias current of CCCII and the circuit possesses low THD for a wide range of signal amplitudes. Extensive simulations are performed to verify the utility of the proposed circuit.

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Lambrechts, Johannes W., and Saurabh Sinha. "Estimation of signal attenuation in the 60 GHZ band with an analog BiCMOS passive filter." International Journal of Microwave and Wireless Technologies 7, no. 6 (July 17, 2014): 645–53. http://dx.doi.org/10.1017/s1759078714000956.

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Prediction of millimeter(mm)-wave radio signals can be beneficial in recreating and repeating atmospheric conditions in a controlled, laboratory environment. A path-loss model has been proposed that accounts for free-space losses, oxygen absorption, reflection and diffraction losses, and rain-rate attenuation at mm-wave frequencies. Two variable passive low-pass-integrated circuit filter structures for attenuation in the 57–64 GHz unlicensed frequency band have been proposed, designed, simulated, prototyped in a 130-nm SiGe bipolar complementary metal-oxide semiconductor process, and measured. The filters are based on the Butterworth and Chebyshev low-pass filter topologies and investigate the possibility of using the structures to perform amplitude attenuation of mm-wave frequencies over a short distance. Both filters are designed and matched for direct coupling with equivalent circuit models of dipole antennas operating in this frequency band. Full integration therefore allows prediction of atmospheric losses on an analog, real-time, basis without the requirement of down-converting (sampling) to analyze high-frequency signals through a digital architecture. On-wafer probe measurements were performed to limit parasitic interference from bonding wires and enclosed packaging.

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Jerabek, Jan, Roman Sotner, Jan Dvorak, Josef Polak, David Kubanek, Norbert Herencsar, and Jaroslav Koton. "Reconfigurable Fractional-Order Filter with Electronically Controllable Slope of Attenuation, Pole Frequency and Type of Approximation." Journal of Circuits, Systems and Computers 26, no. 10 (March 8, 2017): 1750157. http://dx.doi.org/10.1142/s0218126617501572.

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This paper presents design of electronically reconfigurable fractional-order filter that is able to be configured to operate as fractional-order low-pass filter (FLPF) or fractional-order high-pass filter (FHPF). Its slope of attenuation between pass band and stop band, i.e., order of the filter, is electronically adjustable in the range between 1 and 2. Also, pole frequency can be electronically controlled independently with respect to other tuned parameters. Moreover, particular type of approximation can be also controlled electronically. This feature set is available both for FLPF and FHPF-type of response. Presented structure of the filter is based on well-known follow-the-leader feedback (FLF) topology adjusted in our case for utilization with just simple active elements operational transconductance amplifiers (OTAs) and adjustable current amplifiers (ACAs), both providing possibility to control its key parameter electronically. This paper explains how reconfigurable third-order FLF topology is used in order to approximate both FLPF and FHPF in concerned frequency band of interest. Design is supported by PSpice simulations for three particular values of order of the filter (1.25, 1.5, 1.75), for several values of pole frequency and for two particular types of approximation forming the shape of both the magnitude and phase response. Moreover, theoretical presumptions are successfully confirmed by laboratory measurements with prepared prototype based on behavioral modeling.

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Sipkin, Stuart A., and Arthur L. Lerner-Lam. "Pulse-shape distortion introduced by broadband deconvolution." Bulletin of the Seismological Society of America 82, no. 1 (February 1, 1992): 238–58. http://dx.doi.org/10.1785/bssa0820010238.

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Abstract The availability of broadband digitally recorded seismic data has led to an increasing number of studies using data from which the instrument transfer function has been deconvolved. In most studies, it is assumed that raw ground motion is the quantity that remains after deconvolution. After deconvolving the instrument transfer function, however, seismograms are usually high-pass filtered to remove low-frequency noise caused by very long-period signals outside the frequency band of interest or instabilities in the instrument response at low frequencies. In some cases, data must also be low-pass filtered to remove high-frequency noise from various sources. Both of these operations are usually performed using either zero-phase (acausal) or minimum-phase (causal) filters. Use of these filters can lead to either bias or increased uncertainty in the results, especially when taking integral measures of the displacement pulse. We present a deconvolution method, based on Backus-Gilbert inverse theory, that regularizes the time-domain deconvolution problem and thus mitigates any low-frequency instabilities. We apply a roughening constraint that minimizes the long-period components of the deconvolved signal along with the misfit to the data, emphasizing the higher frequencies at the expense of low frequencies. Thus, the operator acts like a high-pass filter but is controlled by a trade-off parameter that depends on the ratio of the model variance to the residual variance, rather than an ad hoc selection of a filter corner frequency. The resulting deconvolved signal retains a higher fidelity to the original ground motion than that obtained using a postprocess high-pass filter and eliminates much of the bias introduced by such a filter. A smoothing operator can also be introduced that effectively applies a low-pass filter. This smoothing is useful in the presence of blue noise, or if inferences about source complexity are to be made from the roughness of the deconvolved signal.

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ZENG Wei-qing, 曾炜卿, 陈力荣 CHEN Li-rong, 徐忠孝 XU Zhong-xiao, 李淑静 LI Shu-jing, and 王海 WANG Hai. "The Design of Temperature Controlled and Frequency Tunable Narrow-band Fabry-perot Filter." Acta Sinica Quantum Optica 22, no. 4 (2016): 386–92. http://dx.doi.org/10.3788/asqo20162204.0386.

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Singh, Balraj, S. Parthipan, T. S. Rathore, and B. B. Bhattacharyya. "A Note on Single-Grounded-Resistor-Controlled Variable Frequency Active RC Notch Filter." IETE Journal of Research 35, no. 1 (January 1989): 25–27. http://dx.doi.org/10.1080/03772063.1989.11436785.

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Mohammad Noor, S. Z., N. Rosmizi, N. Aminudin, and Faranadia A.H. "Investigation of Passive Filter Performance on Three Phase DC to AC Converter." International Journal of Power Electronics and Drive Systems (IJPEDS) 9, no. 3 (September 1, 2018): 1016. http://dx.doi.org/10.11591/ijpeds.v9.i3.pp1016-1028.

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This work presents investigation of passive filter performance on three-phase inverter with 180° conduction mode. The simulation model of the inverter is developed by using MATLAB/Simulink. The power circuit used Insulated Gate Bipolar Transistor (IGBT) as switching device. The inverter is controlled by using bipolar Sinusoidal Pulse Width Modulation (SPWM) technique. The IGBT was set to 25 kHz for switching frequency (fs). Three types of passive filters which are LC, RC and PI filters are used to investigate the ability to remove the unwanted signal that occurred on the inverter. The result is analyzed based on the performances of output filter in term of Total Harmonic Distortion in voltage (THDv), current (THDi), shape of output voltage and current. The THD must be less than 5% at rated inverter output voltage or current by referring to IEC 61727 Standard. The passive filter is modeled in MATLAB/Simulink environment to study the characteristics and performance of the filters.

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Wang, San-Fu, Hua-Pin Chen, Yitsen Ku, and Ming-Xiu Zhong. "Voltage-Mode Multifunction Biquad Filter and Its Application as Fully-Uncoupled Quadrature Oscillator Based on Current-Feedback Operational Amplifiers." Sensors 20, no. 22 (November 22, 2020): 6681. http://dx.doi.org/10.3390/s20226681.

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This research introduces a new multifunction biquad filter based on voltage mode (VM) current-feedback operational amplifier (CFOA) and a fully uncoupled quadrature oscillator (QO) based on the proposed VM multifunction biquad filter. The proposed VM multifunction biquad filter has high impedance to the input voltage signal, and uses three CFOAs as active components, while using four resistors and two grounded capacitors as passive components. The VM CFOA-based multifunction biquad filter realizes band-reject, band-pass, and low-pass transfer functions at high-input impedance node simultaneously, which has the feature of easy cascading in VM operation without the need for additional voltage buffers. Additionally, the filter control factor parameter pole frequency (ωo) and quality factor (Q) of the proposed VM multifunction biquad filter can be independently set by varying different resistors. By slightly modifying the VM multifunction biquad filter topology, a VM fully-uncoupled QO is easily obtained. The difference from the previous VM CFOA-based multifunction biquad filter is that the proposed VM CFOA-based multifunction biquad filter can be independently controlled by the filter control factor parameters, ωo and Q. The proposed VM CFOA-based multifunction biquad filter can be transformed into a VM QO with fully-uncoupled adjustable of the oscillation condition and the oscillation frequency. The oscillation condition and the oscillation frequency can be fully-uncoupled and controlled by varying two sets of completely different resistors. The proposed VM fully-uncoupled QO solves the amplitude instability. The constant amplitude ratio of two quadrature sinusoidal waveforms can be realized when tuning FO. PSpice simulation and experimental results prove the performances of the proposed VM multifunction filter and VM fully-uncoupled QO. Simulation and experimental results confirm the theoretical analysis of the proposed circuits.

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Pandey, Neeta, Praveen Kumar, and Jaya Choudhary. "Current Controlled Differential Difference Current Conveyor Transconductance Amplifier and Its Application as Wave Active Filter." ISRN Electronics 2013 (February 28, 2013): 1–11. http://dx.doi.org/10.1155/2013/968749.

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This paper proposes current controlled differential difference current conveyor transconductance amplifier (CCDDCCTA), a new active building block for analog signal processing. The functionality of the proposed block is verified via SPICE simulations using 0.25 μm TSMC CMOS technology parameters. The usefulness of the proposed element is demonstrated through an application, namely, wave filter. The CCDDCCTA-based wave equivalents are developed which use grounded capacitors and do not employ any resistors. The flexibility of terminal characteristics is utilized to suggest an alternate wave equivalents realization scheme which results in compact realization of wave filter. The feasibility of CCDDCCTA-based wave active filter is confirmed through simulation of a third-order Butterworth filter. The filter cutoff frequency can be tuned electronically via bias current.

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Chuluunbaatar, Z., C. Wang, and N. Y. Kim. "Miniaturized Bandpass Filter Using a Meandered Stepped-Impedance Resonator with a Meandered-Line Stub-Load on a GaAs Substrate." Scientific World Journal 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/809809.

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This paper reports a compact bandpass filter with improved skirt selectivity using integrated passive device fabrication technology on a GaAs substrate. The structure of the filter consists of electromagnetically coupled meandered-line symmetric stepped-impedance resonators. The strength of the coupling between the resonators is enhanced by using a meandered-line stub-load inside the resonators to improve the selectivity and miniaturize the size of the filter. In addition, the center frequency of the filter can be flexibly controlled by varying degrees of the capacitive coupling between resonator and stub-load. To verify the proposed concept, a protocol bandpass filter with center frequency of 6.53 GHz was designed, fabricated, and measured, with a return loss and insertion loss of 39.1 dB and 1.63 dB.

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Booma, Nagarajan, S. Rama Reddy, and M. Beryl. "Design and Simulation of Energy Efficient Fixed Frequency Pulse Controlled Power Converter for Induction Melting Application." Advanced Materials Research 768 (September 2013): 404–10. http://dx.doi.org/10.4028/www.scientific.net/amr.768.404.

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This paper discusses the design and simulation of pulse width modulated based circuit for induction melting application. This high frequency inverter topology have the practical advantages of energy saving, clean environment, high output power due to low switching losses, less electromagnetic noise and low total harmonic distortion. This two stage power converter has single phase full bridge rectifier, DC filter, zero voltage switching pulse width modulation controlled high frequency inverter. In this work, the steady state operation and control strategy of pulse width modulated high frequency inverter is analyzed. In order to achieve energy efficiency switching losses are reduced by operating the inverter above resonance frequency. Input side supply harmonics is also reduced using EMI filter. The simulation of the designed high frequency power supply is carried out at a frequency of 20 kHz using MATLAB simulink tool. Simulation results proof the energy saving due to reduction in switching losses of the presented control strategy and reduction in harmonic distortion of the presented power supply for induction heating load.

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Journal articles on the topic 'Controlled frequency filter'

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