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Design and realization of V/I and I/V symmetrical converters
Chrást, Jakub ; Koton, Jaroslav (referee) ; Jeřábek, Jan (advisor)
Master´s thesis deals about design of symmetrical converters voltage on current and current on voltage. These converters will be used for measuring frequency characteristics of differential frequency filters. Current feedback amplifier was used as active element. Some circuits useful for this function were chosen. Various integrated circuits were put into these circuits. All variations were simulated in computer program Orcad. In terms of computer simulations the best variation was chosen. Selected variants were practically verified and control measuring were realized.
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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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Utilization of signal-flow graphs in design of the fully-differential filters
Žůrek, Radomil ; Kubánek, David (referee) ; Jeřábek, Jan (advisor)
The dissertation deals with the design of fully differential frequency filters using the signal flow graphs. It presents the procedures for designing frequency filters, focusing on the active elements such as multiple-output current followers (MO-CF) and digitally adjustable current amplifiers (DACA), which work in a current mode. It is theoretically discussed the issue of designing the M-C graphs, which are the graphic analogy of voltage and current incidence matrices. There are also presented three designs of 2nd order frequency filter circuits using the indirect method of design by M-C graphs and one circuit design using the direct method. The results of each simulation and measurement are presented in a module frequency characteristics. Finally, there is a summary of M-C graphs characteristics and applicability.
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Design of adjustable fully-differential filters with current active elements
Polášek, Lubomír ; Koton, Jaroslav (referee) ; Jeřábek, Jan (advisor)
The master thesis deals with design of the fully differential frequency filters working in the current mode and is focused on possibilities of the natural frequency and the quality factor adjustment. At the beginning, there is a brief description of frequency filters and active elements (MO-CF, FD-CF and DACA), which are used in the thesis. Furthermore, simplified signal flow graphs design method and transformation of passive and active elements to the differential structures are described. The designs of four differential circuitries which provide possibility of tuning the natural frequency or quality factor by the gain of the DACA element are shown in the thesis. Simulation results made in OrCAD program with help of third-order models are included. The practical implementation of the differential frequency filter for tuning of the natural frequency by the DACA elements is shown in the last chapter.
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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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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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Voltage Conveyors in Linear Blocks
Dohnal, Pavel ; Jeřábek, Jan (referee) ; Koton, Jaroslav (advisor)
The main goal of this diploma thesis will be realization of tunable frequency filters using voltage conveyors, that are only little explored yet. At the beginnig of diploma thesis the frequency filters and their types will be defined. The theory of voltage conveyors based on principle of duality results from the character of current conveyors. Accordingly these active components will be closely presented. At first there will be defined individual types of voltage conveyors and their closer characteristics. Then design methods of frequency filters using unconventional active components will be described. There will be defined the method of the total admitance net, subsequently design using synthetic components and at the end there will be presented method using follow graphs that will be used to design concrete circuit solution. Using follow graphs method will be found circuit solutions of current structures with unconventional active components. During searching circuit solutions will be very important the posibility to operate the quality factor. That can be obtained by two ways. One way is the activ operation which is done by coeficients of the activ component. Other way is operating using the passiv component. There are found 26 circuits that realize condition of active operating using two active and four passive components. One of these circuits will be chosen and simulated in simulation program PSpice. To compare both methods of operation there will be compiled some circuit with passive operating with two active and five passive components and one of the passive components will be able to operate the quality factor. This circuit will be simulated in the simulation program PSpice again. The circuit will be real compiled and experimentaly measured in laboratory. Results of this measurement will be compared with calculated values and with values acquired from the simulations.
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MPKT communication protocol extension on .NET platform
Görlich, Tomáš ; Malý, Jan (referee) ; Jeřábek, Jan (advisor)
This thesis is focused on extension of MPKT 2008 communication protocol. It has been made analysis of this protocol version and proposals to improve and extend this version with other options have been raised. It has been created a new version of the protocol on the basis of the proposals. Then the .NET platform has been presented and its architecture has been described. The C# language available on the .NET platform has been chosen to implement the new protocol version and its facilities for network communication and threading have been described. It has been said an assessment of the application of this programming language in practical lessons. A proposal to update tutorial texts has been made.
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Analysis of the wireless network security
Bencel, Jozef ; Koutný, Martin (referee) ; Jeřábek, Jan (advisor)
This master's thesis deals with security of wireless network standard 802.11. There are described security mechanisms as hide SSID, MAC address filtering, WEP, WPA, WPA2 protocols. There are described also the most often kinds of attacks (Denial of Service, disclosure WEP key, Man-in-the-Middle). The work contains investigation of used security mechanisms in wireless networks in parts of Brno. There were used NetStumbler and inSSIDer applications for this measurement. The last part of work contains measurement of security mechanisms (WEP, WPA, WPA2) effect to transfer rate from the point of view of the end user. The measurement was realized with Iperf application.
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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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