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High-order frequency filters using modern active elements
Chrást, Jakub ; Minarčík, Martin (referee) ; Jeřábek, Jan (advisor)
The bachelor thesis deals with the designing of active frequency filters of the second – order which is useful for the construction of cascade high – order filters. These filters were designed by means of autonomous circuits. Multiple current mirror and inverter MCMI, current operational amplifier COA and current differencing transconductance amplifier CDTA were used as active elements. Designing is focused on the circuits using MCMI. Designed filters work in current mode. In the introductory part there are described general characters of frequency filters. The second part includes the methods of construction high – order filters, the third part contains the description of active elements used. The design we can find in the fourth part. The functionality of filters was verified by computer simulation. One of the optimal filters was practically verified by available component UCC 0520. Two other filters were used for the construction of the fourth – order filter.
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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 filters in current, voltage and hybrid modes with OA, using autonomous curcuits
Jašek, František ; Minarčík, Martin (referee) ; Vrba, Kamil (advisor)
This bachelor‘s thesis describes the procedure of design of frequency filters with operational amplifier using autonomous circuit. At first there is the procedure of an inference common and autonomous circuits with operational amplifier, of which they are follow on derived know and unknown engagement of frequency filters in voltage, current and hybrid mode. In all these inference frequency filters were determine a transmission function, according them is evidently about which frequency filters is discussed (low pass, high pass, band pass, band stop). The derived filter circuits are then selected two unknown involvement, which is set out in detail the procedure in the design of the frequency filter. Both suggestion circuits was verified by a simulation which results are noticed in this thesis and sequentially was made an experimental verified by mounting product in SMD. On this product was made a metering of a transmission and phase frequency characterization which was recorded in the graph. In fine there is a description of propriety of suggestion frequency filters for a practically use in this production.
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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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Laboratory kit for demonstration of active low pass, high pass and band pass filter by Sallen-Key structure
Kadlec, Michal ; Smejkal, Vladimír (referee) ; Slezák, Josef (advisor)
The main aim of this work is to design electric circuit for realizing of low pass, high pass and band pass filter using Sallen – Key structure. It is active filter so this work pays attention to choose the suitable active element. I will analyze individual types of frequency filters, simulate designed structure and will choose suitable computing amplifier for our structure. I will simulate every circuit with ideal operational amplifier, with operational amplifier having real parameters and finally with our chosen operational amplifier. I will confront the difference of individual circuit, influence of real parameters of amplifier for the general process of resultant filter modul characteristics. I closer take a look at the output resistance influence of operational amplifier for the modul characteristics of choosen circuit (low pass filter). This project also includes the summary and analyses of individual possibilities of the electronic control applied to active filter parameters. The part of the project is also detailed analyze and process of realization of the final connection of laboratory instrument.
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Utilization of CDTA and CFTA elements in electrical circuits and frequency filters
Kotlán, Petr ; Herencsár, Norbert (referee) ; Kubánek, David (advisor)
Thesis deals about active component in current mode, CDTA (current differencing transconductance amplifier) and CFTA (current follower transconductance amplifier). CDTA compares two input currents. Outcome current comes trough added terminal Z to load. Caused voltage is transfered to output current by transconductance g. Output surrents shall be possitive (terminal X+) or negative (terminal X-). In contrast to CDTA, CFTA has one current input. Components were used in filters and oscillators. Some filters of second order realized simultaneously low, hight and nad pass were designed. Then, the transfer of filters with diverse topology with opperational amplifier to filter with CDTA and CFTA was shown. Some oscillators were designed. Designed circuits were simulated. Transistor models of CDTA and CFTA were created to purpose of simulation. This components can be realized by AD844 and MAX435. There are shown the conclusions of AC analysis of filters and transission analysis of oscillators. The thesis contains practical realization of second order frequency filter also. Device was made like a PCB by smd. CFTA was realized by components AD844 and MAX435.
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Adaptive frequency filter
Kříž, Petr ; Hájek, Karel (referee) ; Sedláček, Jiří (advisor)
The aim of this work is to design a filter of the type low–pass of order 5th with Butterworth’s approximation in the range of over-tuning 10 – 100 kHz and if it will be possible so! achieve even higher marginal frequencies. To compare two typical representatives of the frequency filters cascading and non-cascading synthesis from the viewpoint the accuracy of an! approximation function, sensitivity to the tolerance values of components, number of the components (mainly OZ) and viability, especially the possibility of electronic over-tuning in selected frequency range. On the basis of these conditions will be chosen one design, which will be realized later. Further it will be necessary to consider the possibilities of electronic over-tuning and to choose for this over-tuning suitable component, to design user management changes of marginal frequency fm by the help of keyboard + LCD and control application on the PC. For this hardware will be programmed appropriate control software. At the end of this work will be constructed appropriate device, which fullfils requirements written above and will be subjected to the laboratory measurements that verify function of this device. The constructional details of the filter are presented in the enclosure at the end of this work. At the CD are available all materials, which were created during the master’s thesis or which are necessarily concerned.
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Frequency Filters with Controllable Current Followers
Novotný, Matouš ; Herencsár, Norbert (referee) ; Koton, Jaroslav (advisor)
Submitted work engage in suggestion and realization of frequency-selection filters with usage one or more active devices CMI (Current Mirror and Inverter). The preamble of thesis is applied to theory of frequency-selection filters and possible usage of them. The projected circuit layouts are discussed next to would be possible change some of choice parameters of frequency-selection filter. The part of thesis is numerical suggestion of found solutions, their simulation in suitable program and realization.
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Active Frequency Filters with Minimal Configuration
Preclík, Milan ; Jeřábek, Jan (referee) ; Koton, Jaroslav (advisor)
This work deals with exploitation of multiple current and voltage gates of active components. After that an optimal circuit´s scheme choice, its simulation and subsequent realization of frequency filter follow. First of all there is a common description of frequency filters and current and voltage conveyors. Furthermore the text focuses on searching circuit´s schemes of second-level frequency filters, described by characteristical equation. These equation make an easy numerical concept possible. New circuits with one active component and with a minimal number of pasive components are searched by using the method of autonomous circuits. The choice of resulting circuit based on simulations executed in Orcad is next in line. The work concludes with verification of a proper function of our filter.
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