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Multifunctional analog frequency filters
Žůrek, Radomil ; Koton, Jaroslav (referee) ; Minarčík, Martin (advisor)
Main topic of this bachelor thesis are the frequency filters and their application. It presents multifunction frequency filter circuits with focus on active circuit elements like current conveyors (GCC), voltage conveyors (GVC) and transconductance amplifiers (OTA), which operate in both voltage and current modes. Then it presents the outcomes of designing 26 second order frequency filters, all operating in both voltage and current modes. It discusses in theory the problematics of M-C graph design, which is graphics-based analogy of voltage and current incidental matrices. Selected circuit designs are examined as examples with their transfer functions determined and results presented as module frequency characteristics. Individual M-C graphs (signal flow graph) are designed for each filter circuit. In conclusion are summarized the characteristics of M-C graphs and their suitable applications.
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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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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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Design of frequency filters with non-traditionally combined active elements
Danyi, Ivo ; Koton, Jaroslav (referee) ; Jeřábek, Jan (advisor)
This paper discusses the frequency second-order filters that work in the current mode. As active elements are used VDTA (voltage differential transconductance amplifier) and CCTA (Current Conveyor Transconductance Amplifier) design method as a method is used to graph of signal flow. They are designed and analyzed four frequency filters. The first uses only one element VDTA and is a multifunctional frequency-controllable frequency filter of the second order. The second is composed of two elements, is VDTA fully controllable multifunctional frequency filter of the second order. The third uses one element CCTA represents a multifunctional frequency filter of the second order without control. The fourth element uses a single CCTA and VDTA and is a multifunctional frequency-controlled frequency filter of the second order. All frequency filters are subjec- ted to sensitivity analysis and simulated for ideal and non-ideal active element. Second circuit wiring with two VDTA elements is realized and analyzed the characteristics of this filter.
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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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Filtering structures containing a fractional-order elements
Kubát, Pavel ; Kubánek, David (referee) ; Dvořák, Jan (advisor)
Bachelor work deals with fractal order frequency filters. The first part describes basic division frequency filters, the following part describes fractional order frequency filters and design of the circuit with fractal order. The following part contains active elements that are used for the design of the frequency filters. The last theoretical part shows design method for frequency filters, where signal flow graph is shown. Realisation, simulation and measurement are described in the practital parts.
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Voltage Conveyor Conception Design and Its Applications
Minarčík, Martin ; Vrba, Kamil (advisor)
This doctoral thesis deals with a voltage conveyor as a new active element for an analog signal processing. Various types of the voltage conveyors have been defined as a dual active elements to current conveyors based on a duality principle. Conception of a new active element that can supply all types of the voltage conveyors have been proposed. The active element has been named an universal voltage conveyor – UVC. A voltage follower is a basic building block of the UVC. The well-known circuit realization of the voltage follower comes from four transconductance amplifiers with key parameters (voltage transfer and output resistance) derived from relative accuracy of used transconductance amplifiers has been used by UVC fabrication. A new circuit realization of the voltage follower comes from three transconductance amplifiers with key parameters also derived from relative accuracy of used transconductance amplifiers has been designed. Further the doctoral thesis deals with a frequency filter with the voltage conveyors design using signal flow graphs. Various graphs of the voltage conveyors comes from the various circuit analysis methods with non-regular active elements have been created. A basic graph of the voltage conveyor has been designed with help of a known controlled sources graphs. This graph have been used to design of multifunctional frequency filters, filters with high input and low output impedance and controlled frequency filters. A design procedure have been created so that in specific step of the frequency filter design the basic graph of the voltage conveyor could be extended to graph of any type of the voltage conveyor. Thereby a practical usage of various types of the voltage conveyors has been finding out. Further a new method of frequency filter design based on expanding of the signal flow has beenproposed.
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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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Tunable Universal Fully-Differential Filter With
Operational Transresistance Amplifier
Polesakova, Zuzana
The new single-ended (S-E) second order frequency filter providing transfer function of Low Pass (LP), High Pass (HP), Band Pass (BP), Band Stop (BS) and All Pass (AP) is presented in this paper. The cut-off frequency is tunable up to 3 MHz. Also the fully-differential (F-D) version of the filter is presented and so is the transformation method which is in this case the Signal Flow Graph (SFG). The design filter can be implemented with discretive active devices or as an Integrated Circuit (IC). The features of both S-E and F-D filters are verified using PSpice simulations comparing ideal and behavioral models of the active devices.
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Filtering structures containing a fractional-order elements
Kubát, Pavel ; Kubánek, David (referee) ; Dvořák, Jan (advisor)
Bachelor work deals with fractal order frequency filters. The first part describes basic division frequency filters, the following part describes fractional order frequency filters and design of the circuit with fractal order. The following part contains active elements that are used for the design of the frequency filters. The last theoretical part shows design method for frequency filters, where signal flow graph is shown. Realisation, simulation and measurement are described in the practital parts.
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