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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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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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Design and analysis of electronically reconfigurable filtering structures
Kříčka, Tomáš ; Dvořák, Jan (referee) ; Langhammer, Lukáš (advisor)
This bachelor thesis deals with the proposal of analog filters with the ability of the electronic reconfiguration. The main aim was to propose three fully electronically reconfigurable filters using different methods. The work focuses on the use of modern active elements that ensure the electronic reconfiguration. Specifically on operational transconductivity amplifiers, second-generation current conveyors and current amplifiers. The transfer functions are simulated in the Orcad PSpice software, at the ideal and behavioral level. Sensitivity and parasitic analysis is applied to the two proposed filtration structures. Both structures are made on printed circuit boards, which are measured and then their transfer functions are compared with the simulated functions.
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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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Electronically reconfigurable frequency filters
Gajdoš, Adam ; Langhammer, Lukáš (referee) ; Jeřábek, Jan (advisor)
The aim of the thesis was design of reconnection-less and electronically reconfigurable filters of SISO type with non-traditional active elements. Adjustability of bandwidth or quality factor is also required. First part of the thesis deals with theoretical analysis of filters, their operation modes and design of frequency filters using Signal-flow graph method aswell. Last but not least, electronical reconfiguration of transfer function and parasitic analysis was discussed. Another part describes active elements used in the practical part of thesis. Behaviors and design of active elements using existing circuits (e.g. UCC,EL2082) are described and their transformation into the Signal-flow graph form too. In the practical part five reconnection-less and reconfigurable filters of SISO type was designed using SNAP program. Simulations were done using Orcad program with ideal and real simulation models of active elements. Last part deals with filter design in EAGLE and experimental measurement.
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Frequency filters with untraditional combination of active elements
Filgas, Jaroslav ; Herencsár, Norbert (referee) ; Jeřábek, Jan (advisor)
The Bachelor’s thesis deals with the theory and designing of analog frequency filters of the second order, which operate in current mode and use the untraditional combination of active elements. The filters are designed by means of the autonomous circuits. Active elements used in the design is Multiple Output Current Follower MO-CF, Digitally Controlled Current Amplifier DACA, Generalized Current Mirror and Inverters GCMI, Balanced Operational Transconductance Amplifier BOTA, Inverting Current Conveyor 1st and 3rd Generation ICCI/ICCIII and Universal Voltage Conveyor UVC. The proposed filters work in current mode and their ideal and real models are verified in the simulation environment OrCad. The thesis is structured into five chapters including the conclusion. The first chapter gives the general characteristics of the frequency filters, types of filter functions, types of filters and general equations. The second chapter is devoted to the theory of the active elements. The third charter is about methods of designing and the fourth includes custom designed filters, including their transfer functions and the results verify their functionality in the simulation environment.
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