Ústav radioelektroniky


Recent Submissions

Now showing 1 - 5 of 216
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    Design of Building Blocks for Fractional-Order Applications with Single and Compact Active Device
    (IEEE, 2020-07-09) Šotner, Roman; Jeřábek, Jan; Langhammer, Lukáš; Koton, Jaroslav; Polák, Josef; Andriukaitis, Darius; Valinevicius, Algimantas
    This paper introduces new promising applications of VCA822 active device in the fractional-order design of two-ports including very simple and compact solutions of integrator, differentiator, low-pass and high-pass filter. Key feature of the designed circuits is their tunability controlled by current gain of VCA822 not available in case of solution with standard op-amps. Block (principal) structure of the device is explained in detail. PSpice simulation results of the designed circuits indicate usability of these ideas and also simple tunability of the application verified with a fractional-order constant phase element with the order alpha = 1/4.
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    Design of Electronically Adjustable Fractional Order Immittances Using Single Active Device
    (IEEE, 2020-07-09) Šotner, Roman; Jeřábek, Jan; Langhammer, Lukáš; Koton, Jaroslav; Andriukaitis, Darius; Merfeldas, Audrius
    This paper brings new approach for the design and construction of electronically adjustable immittance functions using single compact commercially available active device (VCAS22). Some of parameters of designed circuits can be controlled electronically thanks to type of used active device. Presented design uses RC approximants of fractionalorder element (order 1/4) in three application examples (fractional-order adjustable capacitance, inductance and frequency dependent negative resistor). PSpice simulations confirm expected behavior and tunability described by theoretical expressions (in wide band up to 10 MHz).
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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.