|
|
Unconventional Signals Oscillators
Hruboš, Zdeněk ; Galajda, Pavol (oponent) ; Štork, Milan (oponent) ; Petržela, Jiří (vedoucí práce)
The doctoral thesis deals with electronically adjustable oscillators suitable for signal generation, study of the nonlinear properties associated with the active elements used and, considering these, its capability to convert harmonic signal into chaotic waveform. Individual platforms for evolution of the strange attractors are discussed in detail. In the doctoral thesis, modeling of the real physical and biological systems exhibiting chaotic behavior by using analog electronic building blocks and modern functional devices (OTA, MO-OTA, CCII±, DVCC±, etc.) with experimental verification of proposed structures is presented. One part of theses deals with possibilities in the area of analog–digital synthesis of the nonlinear dynamical systems, the study of changes in the mathematical models and corresponding solutions. At the end is presented detailed analysis of the impact and influences of active elements parasitics in terms of qualitative changes in the global dynamic behavior of the individual systems and possibility of chaos destruction via parasitic properties of the used active devices.
|
|
|
Fully-Differential Frequency Filters with Modern Active Elements
Langhammer, Lukáš ; Dostál, Tomáš (oponent) ; Štork, Milan (oponent) ; Jeřábek, Jan (vedoucí práce)
This doctoral thesis focuses on research in the field of frequency filters. The main goal is to propose and analyze fully-differential current-mode frequency filters employing modern active elements. Presented filters are proposed using current followers, operational transconductance amplifiers, digitally adjustable current amplifiers and transresistance amplifiers. The proposal is focusing on ability to control some of the typical filter parameter or parameters using controllable active elements suitably placed in the circuit structure. Individual presented filters are proposed in their single-ended and fully-differential forms. Great emphasis is paid to a comparison of the fully-differential structures and their corresponding single-ended forms. The functionality of each proposal is verified by simulations and in some cases also by experimental measurements.
|
|
|
Effective Usage of Circuits with Fractional Order in Integrated Circuits
Kadlčík, Libor ; Štork, Milan (oponent) ; Husák, Miroslav (oponent) ; Horský, Pavel (vedoucí práce)
Integration and differentiation are usually known for an integer order (i.e. first, second, etc.); however, a generalization to a fractional (non-integer) order is possible, which can be implemented by fractional-order electronic circuits (or make an approximation) and which provide a new degree of freedom for design. Approximation of fractional-order circuits with discrete components usually employs RC structures with a wide range of resistances and capacitances and appear difficult to use in integrated circuits. This work shows implementation of fractional-order circuits in integrated circuits and their use in circuit design. Lumped-element components (e.g. RC ladder) and distributed elements (e.g. R-PMOScap, consisting of unsalicided polysilicon strip above gate oxide) are used; only analog CMOS process is used, without any special processing steps. The usefulness of fractional-order circuits has been practically demonstrated by realization of several integrated voltage regulators, in which fractional-order circuits implement fractional-order regulation to achieve both tight DC regulation and a good stability of the regulation loop, without requiring a compensation zero or too large external capacitance (some of the regulators even allow a load capacitance from zero to infinity).
|
|
|
Signal Integrity Optimization Techniques for High-Speed Chips Signaling
Ševčík, Břetislav ; Štork, Milan (oponent) ; Horský, Pavel (oponent) ; Brančík, Lubomír (vedoucí práce)
The doctoral thesis deals with signal integrity problems in modern chip circuits. Based on the simulation and practical experiments an optimized second order pre-emphasis signaling technique is proposed. High bandwidth efficiency of signal pre-emphasis together with a minimum voltage swing during signal emphasizing and still lower power dissipation are the main features respected in the proposal. The performed analysis clearly shows that proposed pulse shaping method due to the spectral efficiency can increase the transmission bandwidth of low cost wire channels. The performance of proposed signaling technique is demonstrated on various type channels with higher order transfer function. Additional channel impairments which can occur during transmission channel design are discussed too.
|
|
|
Analog Implementation of Fractional-Order Elements and Their Applications
Kartci, Aslihan ; Štork, Milan (oponent) ; Machado,, José Tenreiro (oponent) ; Brančík, Lubomír (vedoucí práce)
With advancements in the theory of fractional calculus and also with widespread engineering application of fractional-order systems, analog implementation of fractional-order integrators and differentiators have received considerable attention. This is due to the fact that this powerful mathematical tool allows us to describe and model a real-world phenomenon more accurately than via classical “integer” methods. Moreover, their additional degree of freedom allows researchers to design accurate and more robust systems that would be impractical or impossible to implement with conventional capacitors. Throughout this thesis, a wide range of problems associated with analog circuit design of fractional-order systems are covered: passive component optimization of resistive-capacitive and resistive-inductive type fractional-order elements, realization of active fractional-order capacitors (FOCs), analog implementation of fractional-order integrators, robust fractional-order proportional-integral control design, investigation of different materials for FOC fabrication having ultra-wide frequency band, low phase error, possible low- and high-frequency realization of fractional-order oscillators in analog domain, mathematical and experimental study of solid-state FOCs in series-, parallel- and interconnected circuit networks. Consequently, the proposed approaches in this thesis are important considerations in beyond the future studies of fractional dynamic systems.
|
|
|
Reverberation Reduction in Transformer-Less Ultrasonic Sensors for Parking Applications
Ledvina, Jan ; Husák, Miroslav (oponent) ; Štork, Milan (oponent) ; Horský, Pavel (vedoucí práce)
A common feature of modern car is a parking assistant that typically depends on performance of ultrasonic sensors. This doctoral thesis opens question of reverberation reduction in these sensors. Reverberation is unwanted phenomenon that prevents the sensor in short distance ranging, which is crucial in a parking application. The thesis intentionally aims on emerging transformer-less sensor solution. To address the reverberation problem different types of electric damping are studied. From the theory review it became apparent that a combination of multiple damping methods is needed. The proposed practical solution utilizes a nonlinear damping followed by a linear damping. For the linear damping an adaptive shunt tuning method was proposed to address variation in transducer parameters, which enables the system to achieve the fastest damping. To prove viability of this concept a hardware implementing the proposed damping method was developed and using this hardware the methods were evaluated.
|
|
|
Reverberation Reduction in Transformer-Less Ultrasonic Sensors for Parking Applications
Ledvina, Jan ; Husák, Miroslav (oponent) ; Štork, Milan (oponent) ; Horský, Pavel (vedoucí práce)
A common feature of modern car is a parking assistant that typically depends on performance of ultrasonic sensors. This doctoral thesis opens question of reverberation reduction in these sensors. Reverberation is unwanted phenomenon that prevents the sensor in short distance ranging, which is crucial in a parking application. The thesis intentionally aims on emerging transformer-less sensor solution. To address the reverberation problem different types of electric damping are studied. From the theory review it became apparent that a combination of multiple damping methods is needed. The proposed practical solution utilizes a nonlinear damping followed by a linear damping. For the linear damping an adaptive shunt tuning method was proposed to address variation in transducer parameters, which enables the system to achieve the fastest damping. To prove viability of this concept a hardware implementing the proposed damping method was developed and using this hardware the methods were evaluated.
|
|
|
Effective Usage of Circuits with Fractional Order in Integrated Circuits
Kadlčík, Libor ; Štork, Milan (oponent) ; Husák, Miroslav (oponent) ; Horský, Pavel (vedoucí práce)
Integration and differentiation are usually known for an integer order (i.e. first, second, etc.); however, a generalization to a fractional (non-integer) order is possible, which can be implemented by fractional-order electronic circuits (or make an approximation) and which provide a new degree of freedom for design. Approximation of fractional-order circuits with discrete components usually employs RC structures with a wide range of resistances and capacitances and appear difficult to use in integrated circuits. This work shows implementation of fractional-order circuits in integrated circuits and their use in circuit design. Lumped-element components (e.g. RC ladder) and distributed elements (e.g. R-PMOScap, consisting of unsalicided polysilicon strip above gate oxide) are used; only analog CMOS process is used, without any special processing steps. The usefulness of fractional-order circuits has been practically demonstrated by realization of several integrated voltage regulators, in which fractional-order circuits implement fractional-order regulation to achieve both tight DC regulation and a good stability of the regulation loop, without requiring a compensation zero or too large external capacitance (some of the regulators even allow a load capacitance from zero to infinity).
|
|
|
Analog Implementation of Fractional-Order Elements and Their Applications
Kartci, Aslihan ; Štork, Milan (oponent) ; Machado,, José Tenreiro (oponent) ; Brančík, Lubomír (vedoucí práce)
With advancements in the theory of fractional calculus and also with widespread engineering application of fractional-order systems, analog implementation of fractional-order integrators and differentiators have received considerable attention. This is due to the fact that this powerful mathematical tool allows us to describe and model a real-world phenomenon more accurately than via classical “integer” methods. Moreover, their additional degree of freedom allows researchers to design accurate and more robust systems that would be impractical or impossible to implement with conventional capacitors. Throughout this thesis, a wide range of problems associated with analog circuit design of fractional-order systems are covered: passive component optimization of resistive-capacitive and resistive-inductive type fractional-order elements, realization of active fractional-order capacitors (FOCs), analog implementation of fractional-order integrators, robust fractional-order proportional-integral control design, investigation of different materials for FOC fabrication having ultra-wide frequency band, low phase error, possible low- and high-frequency realization of fractional-order oscillators in analog domain, mathematical and experimental study of solid-state FOCs in series-, parallel- and interconnected circuit networks. Consequently, the proposed approaches in this thesis are important considerations in beyond the future studies of fractional dynamic systems.
|
|
|
Signal Integrity Optimization Techniques for High-Speed Chips Signaling
Ševčík, Břetislav ; Štork, Milan (oponent) ; Horský, Pavel (oponent) ; Brančík, Lubomír (vedoucí práce)
The doctoral thesis deals with signal integrity problems in modern chip circuits. Based on the simulation and practical experiments an optimized second order pre-emphasis signaling technique is proposed. High bandwidth efficiency of signal pre-emphasis together with a minimum voltage swing during signal emphasizing and still lower power dissipation are the main features respected in the proposal. The performed analysis clearly shows that proposed pulse shaping method due to the spectral efficiency can increase the transmission bandwidth of low cost wire channels. The performance of proposed signaling technique is demonstrated on various type channels with higher order transfer function. Additional channel impairments which can occur during transmission channel design are discussed too.
|
host ::
RSS.