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Active Frequency Filters for Higher Frequencies
Fröhlich, Lubomír ; Dostál, Tomáš (referee) ; Biolek, Dalibor (referee) ; Sedláček, Jiří (advisor)
This thesis deals with the synthesis and optimization of frequency analogue filters with modern active elements usable for higher frequencies. The thesis is divided into three parts, the first part deals with the problematic concerning Leap-Frog combined ARC structure. Due to a difficult design, this method is not described in a detail and used in practice, although it shows e.g. low sensitivity. Firstly, a complete analysis of individual filters was made (for and T endings) and consequently these findings were used during implementation of this method to NAF program. Finally, samples of real filters were realized (for verification of functioning and correct design). Another very interesting topic concerning filters is usage of coupled band-pass for small bandwidth, where it is necessary to solve the problems concerning ratio of building elements values, but also price, quality, size of coils, sensitivity, Q factors, coefficients etc. That is why in practice a coil is very often substituted with other equivalent lossy and lossless blocks which create ARC filters structure. The design and the possibility of usage of lossy grounded elements were described here (such as synthetic inductors, frequency dependent negative resistor). Some parts of the design are individual computer sensitivity analysis, setting of usage and quality comparison of individual lossy grounded blocks. Besides, a program for these elements was created, it is useful for a quick design and depiction of transfer characteristics. The third part deals with the usage of tuning universal filters consisting three or more operational amplifiers, which secures its universality and possibility to create different kinds of transfer characteristic. In practice, Akerberg - Mossberg and Kerwin - Huelsman - Newcomb are the most used types of filters. These were also compared with less common universal filters. In the end, the possibility of digital tuning of universal filter with the help of digital potentiometers for filters of 10th order and frequency around 1 MHz was shown.
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Studies of Influences of Oscillators Frequency Instabilities in Satellite Communication Systems
Baran, Ondřej ; Baláž, Igor (referee) ; Šimša, Jan (referee) ; Kasal, Miroslav (advisor)
The dissertation thesis deals with a study of an influence of a simultaneous incidence of an additive thermal noise and a multiplicative phase noise on the useful signal transmission in narrowband satellite communication systems. While the additive thermal noise affects the useful signal only on the receiver side of the communication system, the multiplicative phase noise is produced in all system oscillators. One investigates how the receiver filter bandwidth reduction takes effect on the influence of individual noise types. The thesis is divided into four units. The first one (chapters 4 and 5) solves the ways of modeling of both noise types. In the second part (chapter 6), on the simple example, the primary analysis of the phase noise influence is made. Basic modulation schemes used in the satellite communication are also discussed (chapter 7). Third part (chapter 8) is devoted to the modeling of a general digital system with a M PSK modulation made directly on the main carrier wave. The last part (chapter 9) describes the modeling of a digital system with a BPSK modulation on the auxiliary subcarrier wave followed by an SSB modulation on the main carrier wave. General conclusions are deduced from obtained simulation results.
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MICROSTRIP FILTERS USING DEFECTED GROUND STRUCTURE
Vágner, Petr ; Kasal, Miroslav (advisor)
The thesis deals with the microstrip filter design using defected ground structure (DGS). The difference between standard asymmetric microstrip technique and DGS is in using the structures etched in the microwave substrate ground plane. The DGS resonant characteristics are then used in filter design. The thesis consists of three factual parts. The first one (chapter 4) introduces the use of the DGS resonators in the lowpass filter design. It involves experimental analysis of one type of the lowpass filter. The second part (chapter 5) deals with a novel microstrip lowpass filter design method using DGS. The proposed method is verified by simulations and several samples are realized and measured. Finally, the third part (chapters 7 and 8) deals with the bandpass filter design using specific defected ground structure as a resonator. The resonators are used in a coupled resonator structure. Filters of various orders and resonator configurations are designed and simulated. A combination of the DGS resonators and half-wavelength microstrip resonators is introduced as well. Selected samples are realized and measurement results are compared with simulations.
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Higher-order current mirror filters
Semmler, Petr ; Jeřábek, Jan (referee) ; Lattenberg, Ivo (advisor)
The bachelor's thesis deal with designing frequency filters fourth and sixth rule with current component CMI, GCMI and MCMI and with multi-output current mirrors. The introduction presents basic information about frequency filters divided base several views. Next information attention about current mirrors with divided base several views. Theory part is closed information about current component GCMI, CMI, MCMI. Second part my bachelor's thesis deal manual designing frequency filter with method of autonomous circuits. This method were designed several circuit for fourth and sixth rule. Then he was always one circuit selected for the final analysis, an analysis was performed using program PSpice and Snap. The last section is devoted to the replacement of components of current mirrors. It analyzed the functionality of current mirrors including verification of the functionality of filters incorporating current mirrors.
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Frequency filter
Suchánek, Tomáš ; Kubánek, David (referee) ; Káňa, Ladislav (advisor)
The main objective of this thesis is to design and implement integration that will be building block for tunable active filters 2nd range of low , high and band pass through the jet structure Sallen - Key. This work first examines the use of different types of frequency filters, the detailed design of the components and selection of a suitable operational amplifiers for participation. Practical part focuses on the production of the finished product, measure its parameters resulting in graphs.In implementing are used software such as simulation programme Micro-cap and layout editor Eagle.
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Basic measurement on the Vector network analyzer
Lapčík, Josef ; Urbanec, Tomáš (referee) ; Dřínovský, Jiří (advisor)
This bachelor project concerns with a vector network analyzer for measurement of reflection coefficient, carry coefficient and scattering coefficients. Main parts of vector network analyzer and principle of analyzer with relation to possible areas of error correction are described. Possibilities of using modern vector network analyzer are shown in relation to their conception. Second part of the project deals with design of filters and directional coupler designed for measuring on analyzer. Designs of lowpass filter, bandpass filter and branch-line directional coupler are describe in details. Results of filters analysis from program Ansoft Designer and results of measurement on vector network analyzer are appended. The last part of project focus on creation of application for automatic measurement on network analyzer in program interface Agilent VEE.
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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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Defected ground planar filters
Tomíček, Martin ; Vágner, Petr (referee) ; Raida, Zbyněk (advisor)
In the bachelor´s thesis, the microstrip low-pass filter with the defected ground is described. The project deals with the design and the simulation of the filter in Ansoft Designer, confrontation of results between simulation and realized low-pass filter and the discussion of obtained results.
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Adaptive antialiasing frequency filter
Sovadina, Václav ; Murina, Milan (referee) ; Sedláček, Jiří (advisor)
The aim of this project is to become acquainted with the Bessel approximation function and to present the possible connections of the adaptive antialiasing filter. Then, cascade and partition filter realizations are designed and their computer analysis are carried out. Furthermore, the thesis deals with the options of electronic realignment of filters. A common connection of digital potentiometer along with the block diagram of the whole mechanism are described. The next part presents a construction of the analogue part of the filter, measuring of its real characteristics and the control circuit for the analogue part.
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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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