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Adjustable filters with utmost tuning and untraditional active elements
Voráč, Ladislav ; Herencsár, Norbert (referee) ; Jeřábek, Jan (advisor)
The thesis is paid to design frequency filters steerable jet active elements of the MO–CF (Multiple-Output Current Follower) and also newly-developed current active element DACA (Digitally Adjustable Current Amplifier) in the company ON Semiconductor. The first three chapters focus on basic properties of frequency filters, used components and circuit design methods. The digitally controllable current amplifier DACA is used for managing the radio frequency filters and adjust it using the current amplification parameter A through the digital input CTR. For the design of filters of the second order a method of M-C Signal flow graphs is used. This method is in the work proved very useful and contributed to the modification of already designed frequency filters. The fourth chapter describes the actual detailed design of circuits with quality management, or marginal frequencies to the two parameters. Involvement of the proposed filter is simulated in the OrCAD program for different levels of models of the circuit elements. At the end of each filter design there is a comparison of theoretical and simulated values of the adjustable parameters circuit. The conclusion was one of the districts selected for experimental verification, followed by comparing the measured and simulated transmission characteristics.
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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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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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