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    Design of fractional-order transitional filters of the Butterworth-Sync-Tuned, Butterworth-Chebyshev, and Chebyshev-Sync-Tuned types: optimization, simulation, and experimental verification
    (Elsevier, 2024-03-25) Mahata, Shibendu; Kubánek, David; Herencsár, Norbert
    This paper presents the optimal and generalized design of three different fractional-order (FO) transitional filters for the first time in the literature. The transitional filters considered are of the FO Butterworth-sync-tuned, the FO Butterworth-Chebyshev, and the FO Chebyshev-sync-tuned types. A metaheuristic swarm intelligence optimizer, namely the Crow Search Algorithm (CSA), helps to achieve the optimal FO filter model that minimizes the magnitude error with the theoretical function. The accuracy of the proposed approximants is examined for 19 different combinations of orders of the constituent filters for each of the three types of FO transitional filters. Comparisons with the modified stability boundary locus-based second-, third-, and fourth-order filter approximants demonstrate the compactness and superior accuracy of the proposed models. The average performance regarding the approximation accuracy, computational time, and convergence of CSA for solving the proposed filter design problems is investigated. Circuit simulations conducted on the OrCAD PSPICE platform for the proposed filter using the current feedback operational amplifier as an active element highlight good matching between the proposed model and theoretical filter function. Experimental validation is also carried out to justify the practical feasibility of the proposed filter with printed circuit board fabricated FO capacitor emulators.
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    MOSFET-C transimpedance filters with center frequency tunability feature
    (TAYLOR & FRANCIS LTD, 2022-02-28) Metin, Bilgin; Basaran, Yasin; Herencsár, Norbert; Faseehuddin, Mohammad; Cicekoglu, Oguzhan
    In this paper, seven different MOSFET-C transimpedance filters with their corresponding transfer functions and basic filter specifications, are provided. Presented designs show second-order standard band-pass, low-pass, or high-pass characteristics. Moreover, some filters provide both low-pass and band-pass characteristics. Especially, having a tunability feature makes a design more useful and applicable for various communication and instrumentation systems. The selected filter topology was biased under various biasing conditions to tune central frequency by keeping bandwidth constant. To elaborate the design with different aspects, we checked its small-signal performance by introducing both changing temperature and implementation errors. The theoretical results are in detail verified by numerous simulations using Cadence IC6 Spectre analog design environment. In the design, transistors with 1.8 V supply voltage were used and modelled by the SilTerra Malaysia 180 nm CMOS process parameters. The implemented layout, including metal-insulator-metal on-chip capacitors, occupies an area of 175 mu m x 75 mu m, while the total power consumption of the filter is found to be only 128.86 mu W.
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    Novel Design Solution of Reconnection-less Electronically Reconfigurable Filter
    (IEEE, 2019-06-27) Langhammer, Lukáš; Šotner, Roman; Dvořák, Jan; Dostál, Tomáš
    The paper presents a new design solution of a reconnection-less electronically reconfigurable filter (no manual reconnection or topology change is necessary) offering all standard 2nd-order transfer functions (low pass, band pass, high pass, band stop and all pass). The filter can also provide high-pass and low-pass function with transfer zero (HPZ, LPZ), direct transfer and high-pass function of the 1st-order. The design is based on well-known operational transconductance amplifiers (OTAs) and adjustable current amplifiers (ACAs). Moreover, the electronic control of the pole frequency and quality factor of the filter are available. The proposal is verified by PSpice simulations using commercially available devices.
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    Practical Design of RC Approximants of Constant Phase Elements and Their Implementation in Fractional-Order PID Regulators Using CMOS Voltage Differencing Current Conveyors
    (SPRINGER BIRKHAUSER, 2019-03-18) Domanský, Ondřej; Šotner, Roman; Langhammer, Lukáš; Jeřábek, Jan; Psychalinos, Costas; Tsirimokou, Georgia
    This paper brings a practical and straightforward view on the design of circuit elements described by fractional-order dynamics known as the constant phase element (CPE) and their implementation in a novel structure of a PID (or PID in some literature) regulator based on fabricated CMOS voltage differencing current conveyors. Comparison of presented topology with known solutions indicates significant improvements regarding overall simplification, simpler electronic controllability of time constants, and having all passive elements in grounded form. Step-by-step design of the CPE as well as the PID regulator is supported by experiments with active devices fabricated using the C07 I2T100 0.7 m CMOS process (ON Semiconductor). Laboratory tests in frequency and time domain confirm the correct operation of the designed application and the accuracy of the derived results in comparison with the theoretical expectations.
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    Practical design of the voltage controllable quadrature oscillator for operation in MHz bands employing new behavioral model of variable-voltage-gain current conveyor of second generation
    (Springer, 2018-09-30) Šotner, Roman; Polák, Ladislav; Petržela, Jiří; Langhammer, Lukáš
    This paper introduces a new simple behavioral model of variable-voltage-gain (inverting) current conveyor of second generation (VG-(I)CCII) intended for experimental verification of linearly controllable quadrature oscillator operating above 1 MHz. The proposed novel topology implements two models of VG-(I)CCII. Next, its precise design procedure is presented. Operation with constant amplitude levels is ensured from 2.69 to 20.18 MHz, whereas the highest available oscillation frequency achieves 30.1 MHz. The oscillator employs high-speed off-the-shelf active elements, which emulate behavior of current conveyor of second generation with a variable voltage gain between Y and X terminals. The influence of the real features of active elements and printed circuit boards is considered for the estimation (design equations) of the operational conditions of the circuit. Experimental measurements confirmed the validity of the expected results. Novel behavioral model of active device brings significant advantages (variable voltage gain and its polarity control) for its implementation in applications. Simple circuitry of the newly proposed quadrature oscillator and its wideband linear electronic tuning, constant amplitudes and phase shift with frequency tuning are the most notable benefits of our proposed concept, compared to current state-of-the-art solutions.