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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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Nonlinear circuit structures using current and voltage conveyors
Gabriel, Viktor ; Hanák, Pavel (referee) ; Koton, Jaroslav (advisor)
This thesis deals with the use of active components in nonlinear circuits. First the variants of the current and voltage conveyors are theoretically described. Then the thesis deals with the design of the new curcuit structures with nonlinear components, which comes out from the former known realizations. Several possible solutions of the examined circuit have been designed and the most convenient structure has been selected. The chosen solution has been thoroughly analysed in subsequent diploma thesis to enable comparison of the theoretically designed circuit with the practically realized one.
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Design of new active filters, using signal flow graphs
Jašek, František ; Kubánek, David (referee) ; Vrba, Kamil (advisor)
This master’s thesis describes the design of the frequency filters by the help of the graph of the signal flows. There are defined by modern components like GVC (Generalized Voltage Conveyor), GCC (Generalized Current Conveyor), CF (Current Follower), DO-CF (Dual-Output Current Follower), OTA (Operational Transconductance Amplifier), BOTA (Ballanced Operational Transconductance Amplifier) and CFTA (Current Follower Transconductance Amplifier), the graphs of the signal flows, which describe their activity in the thesis. In the other part of the thesis is illustrated the procedure of the design of the frequency filters by the help of the graphs of the signal flows. For the concrete design was selected in the first case as the active component double output current follower and in the second case the CFTA. There are noted all designed circuits of the frequency filters also their characteristic equations in this thesis. The activity of the selected circuits was remitted to the analysis in the simulation program called PSpice. Because the active components, with which was engaged in the design of the filter which doesn’t exist in the real form, that is why the UCC, which is sufficing for attestation of the function of the circuit, was used for the simulation. The simulation was implemented in the frequency range 10 Hz to 10 MHz.
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Modern active elements and their behavior in linear circuit blocks
Kosztyu, Tomáš ; Jeřábek, Jan (referee) ; Koton, Jaroslav (advisor)
The topic of this master’s thesis was a frequency filters and their realization using modern active elements like UVC, UCC, VFA, CFA and OTA. The base point of this thesis was designed frequency filters with these active elements, when the shape of the transfer function will be identical for all structures and compare the characteristics of active elements. The proposed frequency filters are second order with one or two active elements. In the first part of thesis are discussed basic properties of frequency filters, their properties and distribution. Next are described the general characteristics of active filters and their basic elements such as operational amplifier OTA, VFA and CFA, and recently more frequently used voltage and current conveyor. The second part is the frequency filters designed with these elements is the same transfer function. Subsequently, simulations are done all the filters and obtained the frequency response. Finally, these filters are experimentally made and made practical measurements.
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Frequency filters using current active elements
Homola, Radek ; Lattenberg, Ivo (referee) ; Koton, Jaroslav (advisor)
This master´s thesis is about MO-CF, DCCA and CC frequency filters with current active elements proposal. Current active elements, their features, structure and utilization are shown in introduction. A progress propose of universal filter is described in thesis. With the use of active elements has been established an universal filter with basic parameter changes capability (quality and limit frequency). SNAP software was used in this propose and the characteristics simulation have been done in OrCad-PSpice. For control changes of quality and limit frequency was used active element DCCA. The main circuit board of universal controlled filter was made with the EAGLE software. Created sample was measured for each type of filter, the different quality and limit frequency. These values were compared with simulated values of the filter.
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Transform-based filter design technique based on passive structures
Venclovský, Martin ; Koton, Jaroslav (referee) ; Herencsár, Norbert (advisor)
This diploma thesis deals with transformation of passive elements in filter structures onto substitutes with new active element CFTA. A basic characteristic, types of filters, their frequency characteristics and a form of transfer functions are listed in an introduction. After it is introduced a development of signal flow graphs, single type of graphs and their modifications. There is specified the method Mason-Coates graphs which proves as optimal for analysis circuits. There are listed rules for a correct evaluation and make-up the graphs. Further are described active elements CFTA, CDTA and a current conveyor. There are defined active substitutes to a floating and grounded inductance, a floating capacitor and also a floating and grounded resistor in this thesis. Here, there are also designed substitutes to parallel combinations of floating passive elements. All substitutes use CFTA as an active element and the grounded capacitor as a passive element of substitute. There are presented forms of M-C graphs, transfer functions and equations for calculation passive elements of substitute at created equivalents. Functionality of designed substitutes is always verified on second order passive filters by the help of a PC simulation. There are tabular listed defined equivalents with corresponding signal graphs, transfer functions and equations for calculation capacitor of substitute are here tabular listed too. In this work there are defined two ways of connecting defined substitutes within the scope of one circuit that can be used as a simple connection or integration bounded elements. In the case of usage of the integration bounded elements it is possible to reduce total number used active elements. The usage defined substitutions are verified by way of both methods on known higher order passive frequency filter structures. Third order low pass filter is here realized and scaled in frequency scope from 100 Hz to 100 MHz.
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Universal active elements and their usage in frequency filters
Vencálek, Roman ; Kubánek, David (referee) ; Herencsár, Norbert (advisor)
This master’s thesis deals with the advanced universal modern active elements, such as the current and voltage conveyors. The problem with small bandwidth has been fixed due to the quick development in recent years. Current and voltage conveyors are still being researched. The good properties of conveyors promise their possible commercial usage in the future. For the research of current conveyors we can use parts of other integrated circuits and thus get elements with similar properties. This thesis suggests how to make an active filter using the DBTA and FDBTA elements which were created by “combination” of the universal current and voltage conveyor. Simulations were carried out on selected circuits containing the DBTA to verify their properties. It was for finding out about their behaviour in real applications that the circuits were constructed. This enabled the comparison of the results acquired from the simulation programs with the ideal behaviour of the elements and with the models simulating real properties against the values acquired by measurements of the circuits.
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Modeling of the unconventional functional blocks in Pspice
Zetík, Rostislav ; Brančík, Lubomír (referee) ; Petržela, Jiří (advisor)
This master´s thesis on theme Modeling of the unconventional functional blocks in Pspice deals with the design procedures of electronic elements models and should to help with their create. At the beginning the thesis theoretically describes how the models are created and what possibilities for modeling the program Pspice offers. There are drawn near the individual levels of model and their properties. The second main part of thesis shows practically step by step the design procedures of models of the operational amplifier, current and voltage conveyors, OTA, CDTA, immittance inverter and converter and logarithmic amplifier. There are created the models up to 4.th level, the ideal, resistive, frequency dependent and nonlinear. The basic transmission properties, input and output impedance are modeled this way. The created models with sufficient accuracy correspond to the parameters of the commercial elements. This thesis such shows the possibilities of the program for finding of values for model components like stepping or Optimizer tool.
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Solution proposal and analysis of properties of current operational amplifier in bipolar and unipolar technologies
Pawlas, Radovan ; Lattenberg, Ivo (referee) ; Vrba, Kamil (advisor)
This master thesis is about current operational amplifiers and mainly about their internal structures and possible modifications of these structures. The Current operational amplifier consists of several elementary blocks and these blocks are shortly described and used in internal structures of proposed operational amplifiers. Basic elementary blocks of the current operational amplifier are current mirror, diferentional amplifier, current source, transimpedation amplifier and additional elements of a circuit. In this thesis, several elementary structures of the operational amplifiers are introduced. Each amplifier passed through the analysis of the circuit in software MicroCap 9.0. In this software is done the simple DC analysis of the internal structure of the current operational amplifier in connection with a feedback. The solution was focused on bipolar and unipolar technology for each connection. I deal with a method of feedback connection to the operational amplifier and explore real characteristic of the appropriate amplifier in the designed feedback. In principle this design has important influence to the resulting properties of the circuit. Within the analysis of the circuits have been found, how each current operational amplifier works in a defined current range. Every type of surveyed amplifier is closely described, the internal structure is depicted and graph of current transmission of amplifier is shown. At the end of this thesis the amplifiers are compared and there are introduced their advantages and disadvantages.
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