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Controllable Frequency Filters with Modern Active Elements
Preclík, Milan ; Jeřábek, Jan (referee) ; Koton, Jaroslav (advisor)
The work deals with design of transformation cells suitable for realization of higher orders frequency filters with possibility of cutoff frequency control. At first, there is a common description of frequency filters and active elements like current and voltage conveyors. Furthermore assumptions of cutoff frequency control are defined which result in a convenient characteristical equation. Phylosophy of synthetic elements DP , EP , DS , ES including a possibility of change of cutoff frequency is next in line. By exploitation of synthetic elements theory new circuit’s schemes of transformation cells are searched. The work continues with the choice of appropriate transformation cells for resulting circuit’s solutions of frequency filters with possibility of cutoff frequency control by using transfer coefficients of active elements or with help of passive elements. The work concludes with verification of its proper function based on a simulation executed in OrCAD and with practical implementation of choosen circuit’s solution.
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Selected frequency filter design methods using non-traditional active elements
Omasta, Zdeněk ; Koton, Jaroslav (referee) ; Herencsár, Norbert (advisor)
This master’s thesis is bent on comparison of four newest method of analog frequency filter design. After the introductory part, a description of properties and internal structure of active elements (Second-Generation Current Conveyor), VG-CCII (Variable Gain Current Conveyor), VCG-CCII (Voltage and current gained second generation current conveyor) a CFTA (Current Follower Transconductance Amplifier) is mentioned. This active elements are used in subsequent design. At the next part, process of frequency filters design by generalized method of filter design flowing from the full admittance network, by extending autonomous circuits, design using the signal flow graphs theory and design with synthetic high-order elements are presented. Thirty nine autonomous circuits are derived from full admittance networks with one and two active elements CFTA. Selected autonomous circuits are used for direct design of frequency filter and for filter design by extending autonomous circuits. Produced structures guarantee the possibility of controlling the quality factor Q0 independently of the characteristic frequency f0. Three frequency filters are designed by method using the signal flow graph theory. Active elements CFTA, VG-CCI and VCG-CCII are used. Full multifunctional frequency filter with conveyors VG-CCII and VCG-CCII guarantee the possibility of controlling the quality factor Q0 and the characteristic frequency f0 independently of the each other. In last part, from 2nd to 5th order low-pass filters by the method using synthetic high-order elements are designed. The behaviour of the selected filters has been verified by simulations in the PSpice program for all of the mentioned methods separately.
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Pseudo-differential frequency filters operating in current mode
Velič, Ladislav ; Bečková, Zuzana (referee) ; Sládok, Ondřej (advisor)
This bachelor thesis deals with pseudo-differential frequency filters working in current mode. This thesis further describes different types of frequency filters and their characteristics. In the thesis there are described differencies between differential, non-differential and pseudo-differential filters and their schemes. The thesis then shows schemes of pseudo-differential filters working in current mode. Pseudo-differential band-pass filter is in practical part of the thesis constructed and its practical features are compared to the theoretical.
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Design of a New Filter Structure Employing Devices of Fractal Order
Detko, Adam ; Kubánek, David (referee) ; Bečková, Zuzana (advisor)
This thesis deals with fractional order analogue filtration structures. The first part focuses on theory of analog frequency filters, including fractal order. In the next part, some of the active elements that can be used in frequency filters designing are mentioned. In the third part, known integer order filtration structure working in current mode is shown, which is modified to fractal in the next part. Modification to fractional order filter is realized by the RC structure Foster I, which approximates fractal order element, also known as pseudocapacitor. This part also contains calculations. Next part contains simulation results, that have been made with ideal models of active elements. The fifth part deals with the design of original filtration structure and its subsequent modification to fractal order filtration structure. Last part contains results of simulations and their comparison with the theory and for low pass as well comparison with physically measured values.
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Utilization of circuit elements described by fractional-order dynamics in analog phase shifters
Zedka, Radim ; Šotner, Roman (referee) ; Petržela, Jiří (advisor)
This document deals with fractional passive dipole structures, their mathematical description, design methods and practical use with respect to limited frequency range. Two fractional dipole design methods are being described while one of them is used for practical realization of three fractional dipole samples. All of them are well measured and documented. Analog phase shifters implementing this fractional-order dipole are being discussed theoretically and they are practically constructed and measured. Concisely the fractional-order two-port design method implementing biquadratic filters is described.
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Active Filters and their Transformation to Differential Structures
Bečková, Zuzana ; Herencsár, Norbert (referee) ; Vrba, Kamil (advisor)
Bachelor thesis is considered with transformation of single--ended frequency filters to fully--differential structures. Theoretical part contains a brief introduction to frequency filters and short summary of important features of signal flow graphs. Active elements, which are used in designed filters, are shown in the third chapter. Practical part of the thesis shows five single-ended filters (one already published, four newly designed) and their transformation to fully-differential structures. Results of simulations in programms OrCAD and SNAP are shown.
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Fully-differential frequency filters with nontraditional active elements
Dvořák, Jan ; Koton, Jaroslav (referee) ; Jeřábek, Jan (advisor)
Bachelor's thesis deals with designs of fully-differential frequency filters which operate in current mode where it is possible to control their parameters by change the transconductance or the amplification. The first part divides and describes in general frequency filters. Furthermore, there are described active elements together with their simple simulation models. The second part describes the design of frequency filter by M-C signal-flow graph and methods of transforming final circuit to fully-differential structure. Next part presents several structures of the second-order filter with their simulations in non-differential and fully-differential forms. Last part presents designs of boards of printed circuits and measurement results of two chosen circuits.
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Analysis of differential and non-differential filtering structures with adjustable current amplifier
Dvořák, Jan ; Vrba, Kamil (referee) ; Jeřábek, Jan (advisor)
The master thesis deals with designs of the single-ended and the fully-differential secondorder frequency filters with adjustable parameters. This filters operate in the current mode where main element is the current amplifier DACA (Digitally Adjustable Current Amplifier). The first part describes basic behaviour of frequency filters and distribution according to filter funcion, used parts and structure. The second part of thesis describes the design of the frequency filters by the M-C signal-flow graphs and the transformating single-ended structures to the fully-differential forms. The next part deals with properties of the active elements and their simulation models. The following part describe six circuits of the frequency filters with adjustable parameters and their simulations. Four simulation models with different properties were used for simulating of the DACA in the each circuits. The last part deals with the practical design and measurement of the selected frequency filters.
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Synthesis of the electronically reconfigurable frequency filters
Michalička, Filip ; Dvořák, Jan (referee) ; Langhammer, Lukáš (advisor)
This diploma thesis deals with design of reconection-less electronically reconfigurable filter structures which have single input and single output using unconventional active elements, which have ability to adjust one of their parameter e.g. gain or transconductance. The first part describes basic parameters of frequency filters, the division of filters by frequency transfer response and used circuit elements, their operational modes, the principle of reconnection-less electronically reconfiguration and the circuit design method MUNV. Second part describes all active elements used in the proposal of filters, their properties and the implementation using existing transistor-level models. The third part contains the design of three reconnection-less electronically reconfigurable filters and the simulations results obtained from simulation programs OrCAD Capture and PSpice. The obtained results were compared with theoretical behaviour. This part also contains results of these analyses: sensitivity, parasitic, Monte Carlo and temperature to determine the behaviour in varied cases.
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