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Generalized design of frequency filters with operational amplifiers
Dokoupil, Drahomír ; Minarčík, Martin (referee) ; Vrba, Kamil (advisor)
This thesis is about general design of frequency-selection filter with help of autonomous circuits. Operational amplifier has been chosen as active device/element. In the begining of this project is described role of frequency-selection filters in electronics circuits, their basic types and their transmission function. Another part of this thesis dissertate about construction of autonomous circuits, selection of suitable admittance network and it's simplification. Selected autonomous circuits are initial elements to find out known connections of frequency-selection filters. Last part of this thesis describing work with SNAP software, ways to find new connection of filter and describe how autonomous circuit works in voltage or current mode.
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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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Design of linear structures on transistor level
Gajdoš, Adam ; Kubánek, David (referee) ; Koton, Jaroslav (advisor)
Bachelor thesis deals with the development of software for automated design frequency filters using active elements instead of inductors. The first part deals with the allocation of frequency filers by transmitted specrum and type of components used. It also deals with working mode in the circuit. Thesis also focuses on the description developmet environment in Wolfram Mathematica,and overall development and also advantages. The next chapter is devoted to the theoretical description of the program and all the necessary theoretical provisions, that are needed to manage the program, i.e. description modified nodal analysis, replacement of MOSFET transistor for Voltage Controlled Current Source and writing passive elements in programming language too. The last chapter is dedicated to the development of the program and detailed description.
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Synthesis and Analysis of Circuits with Modern Active Elements
Koton, Jaroslav ; Vrba, Kamil (advisor)
The dissertation thesis deals with the synthesis and design of active frequency filters using current (CC) and voltage (VC) conveyors, or current active elements CMI (Current Mirror and Inverter), MCMI (Multi-output CMI) and PCA (Programmable Current Amplifier). As introduction, these active elements are described as suitable for the design of the circuits working in the voltage-, current,- ,and mixed-mode, or in pure current-mode speaking about the current active elements. The new frequency filter structures presented in this thesis using the above mentioned active elements were designed by the generalized autonomous circuit method, transformation cells and signal flow-graph theory. The generalized autonomous circuit method is based on full admittance network to which generalized active elements are connected. The described admittance networks can be used for other active elements. The next method is based on the transformation cells that subsequently are used for the design of synthetic elements with higher-order imittance. Original conditions for the design of such blocks are given that lead to maximal simplicity of the final structure with minimal number of passive and active elements. For effective usage of another method utilizing signal flow-graphs, new reduced graphs of chosen active elements are given. Their usage leads to direct function blocks synthesis with required properties. The functionality and behavior of chosen circuit solutions have been verified by analyses in simulation programs. The active elements were simulated by the universal current conveyor (UCC) or universal voltage conveyors (UVC) that were designed at the FEEC, BUT in cooperation with AMI Semiconductor Design Centre Brno with the CMOS 0.35 m technology. These active elements have been also used for the realization of chosen filter structures. The experimental measurements were performed in the in the frequency range 10 KHz to 100 MHz.
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Active frequency filter using current mode
Paščinský, Jiří ; Dostál, Tomáš (referee) ; Slezák, Josef (advisor)
The aim of this work is design of frequency filter working in current mode. The introduction of the work deals with features and applications of frequency filters. Special attention is paid to the transfer function of the filter. In third chapter different operational modes of electrical circuits and their advantages and disadvantages are discussed. Attention is paid to active blocks suitable for circuits working in current mode. There is description of components AD844 and EL2082 which represent current conveyors of the second generation and are used in the designed filter. The last two chapters deal with design of component values of the frequency filter. The designed circuit was simulated in PSpice and the results were compared with measurments. Also sensitivity and tolerance analysis of the filter were performed.
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Design of frequency filters with active current element
Polášek, Lubomír ; Herencsár, Norbert (referee) ; Vrba, Kamil (advisor)
In my bachelor's thesis I deal with the matter of frequency filters, how to use them, types of transferential functions and various types of approximation that can be used in the design. The next part of my thesis describes various types of active elements, either voltage or current or those working in a mixed mode. My thesis also deals with various techniques that we can use when creating frequency filters. In the final part of my thesis I introduce a scheme of an ideal current amplifier and several possible connexions of autonomous circuits with this element. Several suggestions have been shown, as well as final simulations in a OrCAD software and a possible realization of input and output impedance of a PCA element.
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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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Design of tunable frequency filters with modern current active elements
Stejný, Jiří ; Herencsár, Norbert (referee) ; Jeřábek, Jan (advisor)
This master´s thesis deals an active elements called digitally controlled current amplifier, multiple-output current follower and its usage in tunable frequency filters. These tunable frequency filters operate in a pure current mode. In the first part of this work are presented the different types of current active elements. Universal current conveyor, multiple-output current follower, digitally controlled current amplifier (UCC, MO-CF, DCCA). In the second part of this work are introduced particular methods of design tunable frequency filters. Special attention is given to using the design method of via autonomous circuits because it is one of the most. In the last part of this thesis are designed and computer-simulated individual multifunction tunable frequency filters with those already active yet elements. These filters were designed via autonomous circuits or modification of existing circuits. The functionality of the proposed filtres have been verified by computer simulation. Snap3 program was used for the symbolic analyse of circuit and OrCad PSpice program was used to simulate the characteristics of multifunction filters.
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Multifunction frequency filters using GCMI
Voráč, Ladislav ; Minarčík, Martin (referee) ; Jeřábek, Jan (advisor)
At the beginning of my work are the frequency filter possibilities and their use discussed. I continue with the basic theoretical filter characters, their description through the use of the transfer functions, the transfer filter function of the second rank and further possible filter diversification on active and pasive ones. In the next chapter, there is a current mode introduced with its use and reasons why to pick it up. As next are several active current items descriped, that will be used for construction of the frequency filter of the second rank. The most used item for the application in the pure current mode is GMCI, which easily means Generalized Current Mirrors and Inventors. It is obvious already from its name what does it do, mirror reflecting and inverting. The next chapter talks about the concept method of the autonomous circuit, where in several blocks is the process of the frequency filter concept to be found. Last four chapters are focused on the detailed frequency filters concept, with all its active elements and their simulations. One of the circuit was choosen for the practical realization and at the conclusion it shows the comparison of the measured and simulated transfer parameters.
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Filters with current mirrors
Kotlán, Petr ; Herencsár, Norbert (referee) ; Lattenberg, Ivo (advisor)
A second-order frequency-selection filters with current amplifier design is shortly shown in this bachelor's thesis. An autonomous circuit was modified to be conform with all rules of functionality of filters. A few version of autonomous circuit are shown i this text. The circuits were simulated by a program Microcap expecially transient and AC analysis. The current amplifier was replaced by a current mirror or more precisely by a current inverter. A direct-current and his relations to suplied harmonic signal were investigated. A deformation of a harmonic signal is unwanted. This deformation is ussualy created by the transistors in nonlinear mode. This current have to have special ratio to the alternating-current. A sixth-order filter was created by cascade connection of three second-order blocks. This more intricated circuit is correct. A correct rate of characteristic due for low-pass, high-pass and band-pass was shown thanks AC analysis.
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