The reconfigurable aperture (RECAP) is a reconfigurable antenna consisting of a dense array of electronically controlled elements, which can be manipulated to support many antenna functions within a single architecture. RECAPs are explored herein as an enabling technology for future software defined and cognitive radio architectures, as well as compact wireless devices supporting many bands and services. First, the concept of a parasitic RECAP is developed and analyzed for various communication applications. This begins with the analysis of existing RECAP topologies (e.g. planar and parasitic) using a hybrid method combining full wave simulations and network analysis. Next, a performance versus complexity analysis is performed to assess the use of a parasitic RECAP for the most critical communications functions: pattern synthesis, MIMO communications and physical-layer wireless security. To verify simulation results, a prototype parasitic RECAP is also built and deployed in real propagation environments. Given the potential of adaptive and reconfigurable architectures for providing enhanced security, an idealized reconfigurable antenna is analyzed, resulting in the concept of secure array synthesis. The objective is to find optimal array beamforming for secure communication in the presence of a passive eavesdropper in a static line-of-sight (LOS) channel. The method is then extended to the case of multipath propagation environments. The problem is solved by casting it into the form of a semi-definite program, which can be solved with convex optimization. The method is general and can be applied to an arbitrary array topology with or without antenna mutual-coupling. Due to complexity of the problem, initial attention has been restricted to idealized reconfigurable antennas (smart antennas), where excitation amplitude and phase at each element can be controlled independently. Lastly, reconfigurable antennas are investigated as a solution to support the emerging application of over-the-air (OTA) testing in a low-cost and compact way, resulting in the concept of the reconfigurable over-the-air chamber (ROTAC). First, an idealized two-dimensional ROTAC is analyzed, revealing that the fading distribution, spatial correlation, frequency selectivity, and multipath angular spectrum can be controlled by proper specification of the random loads. Later, a prototype of ROTAC is built to study the fading statistics and angular characteristics of the multipath fields inside a practical chamber.

Falls and injuries related to falls are one of the most common health problems among older people and are becoming increasingly more frequent. Regular exercise has been identified as one of the most effective fall-prevention activities for older people; however, awareness of the impact of exercise programmes and adherence to recommended exercise among the elderly population is generally low. Research examining how an exercise programme is administered to and experienced by elderly community-dwelling people is needed. The overall aim of this thesis was to investigate the feasibility, experiences and effects of and adherence to the fall-preventive Otago Exercise Programme (OEP) with or without motivational interviewing (MI) among community-dwelling people aged 75 years or older. Four studies were performed from October 2012 to May 2016 in a sample of 175 people. Both quantitative and qualitative research methods were used. The methods included the feasibility for conducting a randomized controlled trial (RCT) (I), individual face-to-face interviews (II), an RCT (III) and a prospective cohort study (IV). The intervention was given to two groups. The participants who received OEP with or without MI were compared with a control group that received standard care. The feasibility of performing an exercise intervention with or without MI was acceptable from the perspective of the participating physiotherapists. From the perspective of the older participants performing the exercise with behavioural change support, the inclusion of monitored exercises in everyday life and daily routines was important. The participants also expressed experiencing more strength, improved physical functioning and greater hope for an extended active life during old age. From the short-term perspective, there were significant improvements within the OEP combined with MI group in terms of physical performance, fall self-efficacy, activity level, and handgrip strength. Improved physical performance and fall self-efficacy were also found within the control group; however, corresponding differences did not occur in the OEP group without MI. There were no significant differences between the study groups after 12 weeks of regular exercise. Adherence to the exercises in the pooled exercise group was 81% at the 12-week follow-up. At the 52-week follow-up, the behavioural factors being physically active and obtaining behavioural support in terms of MI had a significant association with adherence to the exercise programme. These studies provide some support for the combination of OEP with MI as the addition of MI was valuable for achieving adherence to the exercise programme over time in older community-dwelling people.

This thesis deals with the application using digitally controlled current amplifiers DACA (Digitally Adjustable Current Amplifer), which was developed at the Department of Telecommunications FEEC in cooperation with ON Semiconductor in 2010. In introduction is decribed the topic of active filters and oscillators. Farther active current components, besides DACA are described current conveyor UCC (Universal Current Conveyor), current amplifier DO-CF (Dual-Output Current Follower), MO-CF (Multiple-Output Current Follower) and FD-CF (Fully Diferential Current Follower) and operational transconductant amplifier BOTA (Balanced-Output Operational Transconductance Amplifer) and MOTA (Multiple-Output Operational Transconductance Amplifier). The following is a compilation of theories circuits using signal flow graphs, which are designed using a simulated filter circuits to control the cutoff frequency or the quality factor. Then design and simulation with auxiliary oscillator circuit AGC for controlling the oscillation frequency. Simulations are conducted with ideal models and with models that include some real properties. The conclusion of this work is devoted to the printed circuit board design for a selected filter circuit realization and measurement.

Semestral thesis deals with fractional-order frequency filters. There is descripe proposal of the filter, their simulations and practical realizations. The first part is focused at the introduction to a frequency filters. The following is chapter which explore various proposals fractional-order frequency filters. The next chapter describes used activ elements in this thesis. Then there is briefly described a method of the signal flow graphs. The following is a description of the theoretical design of lowpass and highpass frequency filter, where order of the filter is between the first and second. Another part deal with the design and simulation of the four circuits. There are two curcuits consists of transconductance amplifiers (BOTA) and two curcuist consists of current followers. The last part of the thesis deals with practical realization of the two fractional-order filters.

Purpose – The purpose of this study is to elaborate security risks with OTA updates within TRÅDFRI:s PAN. To ensure that today’s IoT devices maintains a high and robust standard to protect end-user’s integrity. Method – To answer the questions and to provide research-based evidence the study was carried out as a case study and two methods were applied in the study. An initial literature review in which the Zigbee protocol and it´s process for certification as well as OTA updates was studied. The literature review was followed by a qualitative experiment with focus on how IKEA implemented the PAN-security in practice. Findings – The findings show reduced security within the TRÅDFRI:s PAN when a third party device performs the OTA update. The experiments also questions parts of the certificate issued by Zigbee Alliance. Implications - Due to the increasing popularity of IoT devices, requirements are increasing from a data security perspective. The data security perspective is more important than ever and take up significantly more space during the development process as well as during the life cycle. This study discusses the OTA updates impact on integrity as well as how an established IoT company, such as IKEA, has implemented this necessary feature to maintain its products during the products life cycle. Limitations – Data gathered from the experiment was limited to TRÅDFRI E27 LED Bulb and therefore the result cannot be seen as a generalization of all TRÅDFRI products.

We have been examinining the image of Ostrava on prose of six authors after 1989. Our aim was to find the function of such space in narrative - it can only play role of a scenery (Slawińsky term), sometimes more functions are added, which empasizes the importance of region in literature according to Urbanová: each region can become a theme or be transposed into author ́s aesthetic sense, influence creative method and become an inspiration in various ways. We have also evaluated how much the protagonists identify themselves with the urban space of Ostrava. This has been based on phenomenological approach of Norberg- Schultz Genius loci. In conclusion we have tried to summarize which themes regarding Ostrava become common for examined authors, whether they create a coherent literary utterance about Ostrava, which has similarities with Todorov ́s petersburg text of russian literature.

In my graduation thesis I first of all shortly mentioned frequency–selection filters and their utilisations. However, the base point of this project was to acquaint with different types of signal flow diagrams with whom I should design and analyse frequency-selection filtres with conventional and also innovative active components. As the first I created signal flow diagrams for both voltage and current conveyors. These modern active components are well known today and enable the construction of circuits with better properties than circuits with traditional differentiating amplifiers with voltage feedback. Thereinafter I made signal flow diagrams for OTA component. Transconductancal amplifiers are well known active components used in various areas of analog signal processing. OTA amplifier is in fact the current source controlled by voltage difference, which is characterised by gm transconductance. Ulterior components were IOZ and IZN models of voltage amplifier with voltage gain A. The last component was COA amplifier. It is a current operational amplifier. COA model is fully dual component to VOA, which is classical voltage amplifier. In my project I used filters with two OTA components. This filter offers functions like low-pass filter, band-pass filter, high-pass filter, band-stop filter and two-phase network. Following this I used circuits with two GCC conveyors. These offer band-pass filter, low-pass filter, high-pass filter, band-stop filter and two-phase network. Ultimately I designed filters with COA components, which offer three transmission functions simultaneously (DP, PP and HP). Analysis of these filters was made with a help of PSpice computer programme.

Operational transconductance amplifier and capacitor (OTA-C) filters have outstood among different types of filter due to high frequency and low power capabilities in the main stream digital CMOS technology. They have been widely used in computer hard disk drive (HDD) and wireless communication transceivers. OTA-C filters based on cascade and passive ladder simulation are well-known. However, multiple loop feedback (MLF) OTA-C filters which have certain advantages still have the scope for further research. So far there have been no explicit formulas for current-mode leapfrog (LF) filter design and performance evaluation of current-mode MLF OTA-C filters are still lacking. From application viewpoints, read channels for computer hard disk drives require very high frequency continuous-time filters. This automatically disqualifies active- RC/MOSFET-C filters and OTA-C filters become the only solution. In wireless communications, active-RC/MOSFET-C filters have been proved useful for mobile systems whose baseband frequency falls below a few MHz. However, for wireless LANs with the frequency of several tens of MHz, OTA-C filters are a strong candidate. Whilst in HDD read channels, cascaded OTA-C architectures have been most utilized and in wireless receivers, OTA-C structures based on ladder simulation have been popular, MLF OTA-C filters have not been practically used in either of the applications. This thesis describes some novel designs and applications of multiple loop feedback OTA-C filters with extensive CMOS simulations. Analogue filters for computer hard disk drive systems are first reviewed; the state of the art and design considerations are provided. Three VHF linear phase lowpass OTA-C filters are then designed, which include a seventh-order and a fifth-order current-mode filter based on the follow-the-leader-feedback (FLF) structure and a seventh-order voltage-mode filter using the inverse FLF (IFLF) configuration. These filters all have very low power consumption. The synthesis and design of general current-mode LF OTA-C filters are conducted next. Iterative design formulas for both all-pole and finite-zero functions are derived and explicit formulas for up to sixth-orders are given. These formulas are very easy to use for designing any type of characteristics. Subsequently, linear phase lowpass OTA-C filter design for HDD read channels using LF structures are investigated in details. A current-mode filter and a voltage-mode filter using the fifth-order LF structure are presented. The two filters can operate up to 800MHz and have very small passband phase ripple. Analogue filters for wireless communication baseband applications are also reviewed thoroughly in this thesis, where the design of a fourth-order current-mode FLF Butterworth lowpass OTA-C filter for multi-standard receivers is presented. Then two fifth-order current-mode elliptic lowpass OTA-C filters based on respective LF and FLF structures for wireless communication baseband are designed. Fifth-order voltage-mode IFLF and LF elliptic lowpass filters are also presented. All these MLF baseband filters designed can operate up to 40MHz to cover all important wireless and mobile standards. Simulations show that the LF structures have better dynamic range and stopband attenuation performances than the FLF and IFLF configurations.

The electronics industry has developed incredibly in last few years and the need for low voltage and low power consuming devices is reflected with its growth. A small extension in battery life can be reflected in an order of magnitude in terms of retail prices. From multimedia gadgets (like laptops, mobiles, notebook etc.) to the biomedical device, all applications have seen a rapid advancement. All these devices need a low voltage and low power transceiver to connect with the wireless networks. This PhD thesis is focused on the development of new designing techniques for low voltage, low power integrated circuits, having close attention on circuits suitable for analog devices. The vast majority of high performance analog circuit cells realized in metal–oxide–semiconductor field-effect transistor (MOSFET) technologies traditionally exploits transistors operating in saturation. Meanwhile there exists a region of weak inversion, which was left unexploited until recently, where the behavior of a MOS transistor is similar to a bipolar transistor in qualitative terms. This region could be exploited for the devices which require operating with low voltage supply. Instead of operating in saturation region, the MOS devices employed in this design, operate in weak inversion. The MOS devices in the proposed circuits are bulk-controlled. In the conventional mode of biasing the bulk terminal is left unused and is connected with lowest supply voltage or ground while the gate is usually chosen for the input signal introduction to bias the circuit. The bulk can be used as an input for signal, can lower the threshold of a transistor if biased properly, ultimately lowering the supply voltage requirement of the transistor. In this work a modified Nauta’s Transconductor, which operates on very low voltages and have a tunable transconductance is employed to design filters. The filter constructed can be tuned in the range of few MHz. The proposed filter is operated using a 0.5V supply and its cutoff frequency can be easily adjusted. All circuits are designed and analyzed using a triple well 0.13μm CMOS process. This OTA is further modified to achieve better performance, in order to implement it in a complex filter. In low IF devices the down-conversion of image signal along with the wanted signal at the same frequency is a major problem. Complex filter can easily remove this image signal by applying a frequency shifting operation. A sixth order complex filter by implementing Leapfrog technique is designed using the differential OTA. The filter is designed to meet the Bluetooth and Zigbee standard requirements. The filter operates on a 0.5V supply voltage, and has very good results for Image rejection, sensitivity, noise and the filter is orthogonally tunable. The performance of the filter has been evaluated through simulation results by employing a triple well 0.13μm CMOS process. This filter design can be implemented in the Bluetooth devices used for the biomedical applications. / Η βιομηχανία της ηλεκτρονικής έχει αναπτυχθεί απίστευτα τα τελευταία χρόνια και η ανάπτυξη αυτή συνδυάζεται με την ανάγκη για συσκευές που λειτουργούν σε χαμηλή τάση και με χαμηλή κατανάλωση ενέργειας. Σε ότι αφορά την εμπορική τιμή, μια μικρή αύξηση της διάρκειας ζωής της μπαταρίας μπορεί να αντανακλάται σε μια αύξηση κατά μία τάξη μεγέθους της τιμής. Όλες οι εφαρμογές, από τις συσκευές πολυμέσων (όπως κινητά τηλέφωνα, φορητούς υπολογιστές, notebook κ.λπ.) έως και τις βιοϊατρικές συσκευές έχουν δει μια ταχεία πρόοδο. Όλες αυτές οι συσκευές, για να συνδέονται με ασύρματα δίκτυα, χρειάζονται πομποδέκτη χαμηλής τάσης και χαμηλής κατανάλωσης ισχύος. Η παρούσα διδακτορική διατριβή επικεντρώνεται στην ανάπτυξη νέων τεχνικών σχεδιασμού για ολοκληρωμένα κυκλώματα με έμφαση στα αναλογικά κυκλώματα, χαμηλής τάσης και χαμηλής ισχύος. Η συντριπτική πλειοψηφία των δομικών βαθμίδων αναλογικών κυκλωμάτων υψηλών επιδόσεων πραγματοποιείται σε τεχνολογία μετάλλου οξειδίου ημιαγωγού τρανζίστορ φαινομένου πεδίου (MOSFET) και εκμεταλλεύεται τα τρανζίστορ που παραδοσιακά λειτουργούν σε κόρο. Ωστόσο, υπάρχει η περιοχή ασθενούς αναστροφής, η οποία αφέθηκε ανεκμετάλλευτη μέχρι πρόσφατα, όπου η συμπεριφορά των τρανζίστορ MOS είναι παρόμοια με αυτήν των διπολικών τρανζίστορ. Αυτή η περιοχή θα μπορούσε να αξιοποιηθεί για τις συσκευές που απαιτούν λειτουργία με χαμηλή τάση τροφοδοσίας. Αντί να λειτουργούν στην περιοχή κόρου, τα τρανζίστορ MOS που χρησιμοποιούνται σε αυτό το σχεδιασμό, λειτουργούν σε ασθενή αναστροφή. Τα τρανζίστορ MOS στα προτεινόμενα κυκλώματα είναι ελεγχόμενα από το υπόστρωμα (bulk-driven). Στο συμβατικό τρόπο οδήγησης το υπόστρωμα παραμένει αχρησιμοποίητο και συνδέεται με την χαμηλότερη τάση τροφοδοσίας ή τη γείωση, ενώ η πύλη συνήθως, επιλέγεται για την εισαγωγή σήματος εισόδου και οδηγεί το κύκλωμα. Το υπόστρωμα μπορεί να χρησιμοποιηθεί ως είσοδος για το σήμα, μπορεί να μειώσει την τάση κατωφλίου (threshold voltage) των τρανζίστορ, και τελικά, χαμηλώνει την τάση λειτουργίας του τρανζίστορ. Σε αυτήν την διδακτορική διατριβή χρησιμοποιείται ως διαγωγός (transconductor) ένα τροποποιημένο κύκλωμα Nauta, ο οποίος λειτουργεί σε πολύ χαμηλές τάσεις. Οι ελεγχόμενοι διαγωγοί χρησιμοποιούνται για το σχεδιασμό των προτεινόμενων συντονιζόμενων φίλτρων. Τα κατασκευασμένα φίλτρα μπορούν να συντονιστούν στην περιοχή των λίγων MHz. Τα προτεινόμενα φίλτρα λειτουργούν χρησιμοποιώντας τάση τροφοδοσίας 0.5V και η συχνότητα αποκοπής τους μπορεί εύκολα να προσαρμοστεί. Όλα τα κυκλώματα σχεδιάζονται και εξομοιώνονται χρησιμοποιώντας μία τεχνολογία CMOS triple well 0.13μm. Ο υπό μελέτη τελεστικός ενισχυτής διαγωγιμότητας (Operational Transconductor Amplifier - OTA) έχει τροποποιηθεί περαιτέρω, για να επιτευχθεί καλύτερη απόδοση και να εφαρμοστεί σε ένα μιγαδικό φίλτρο. Η μετατροπή σήματος από τις μεσαίες συχνότητες (IF) στις χαμηλές συχνότητες παρουσιάζεται ένα σημαντικό πρόβλημα όπου μαζί με το επιθυμητό σήμα εμφανίζεται και το σήμα εικόνας στην ίδια συχνότητα. Τα μιγαδικά (complex) φίλτρα μπορούν να αφαιρέσουν εύκολα το σήμα εικόνας, εφαρμόζοντας μια διαδικασία μετατόπισης συχνότητας. Ένα μιγαδικό Leapfrog φίλτρο έχει σχεδιαστεί χρησιμοποιώντας διαφορικούς ενισχυτές διαγωγιμότητας. Το τελικό μιγαδικό φίλτρο δωδέκατης τάξης έχει σχεδιαστεί για να καλύψει τις απαιτήσεις του προτύπου Bluetooth και Zigbee. Το φίλτρο λειτουργεί με τάση τροφοδοσίας 0.5V και έχει πολύ καλά αποτελέσματα στην απόρριψη εικόνας, την ευαισθησία και το θόρυβο. Επίσης, η κεντρική συχνότητα και το εύρος συχνοτήτων είναι ανεξάρτητα ρυθμιζόμενα. Η απόδοση του φίλτρου έχει επαληθευτεί μέσω προσομοίωσης χρησιμοποιώντας μοντέλα τρανζίστορ μιας τεχνολογίας CMOS triple well 0.13μm. Φίλτρα που σχεδιάζονται με την προτεινόμενη μέθοδο μπορούν να εφαρμοστούν σε συσκευές Bluetooth που χρησιμοποιούνται και σε βιοϊατρικές εφαρμογές.

Vast attention has been paid to active continuous-time filters over the years. Thus as the cheap, readily available integrated circuit OpAmps replaced their discrete circuit versions, it became feasible to consider active-RC filter circuits using large numbers of OpAmps. Similarly the development of integrated operational transconductance amplifier (OTA) led to new filter configurations. This gave rise to OTA-C filters, using only active devices and capacitors, making it more suitable for integration. The demands on filter circuits have become ever more stringent as the world of electronics and communications has advanced. In addition, the continuing increase in the operating frequencies of modern circuits and systems increases the need for active filters that can perform at these higher frequencies; an area where the LC active filter emerges. What mainly limits the performance of an analog circuit are the non-idealities of the used building blocks and the circuit architecture. This research concentrates on the design issues of high frequency continuous-time integrated filters. Several novel circuit building blocks are introduced. A novel pseudo-differential fully balanced fully symmetric CMOS OTA architecture with inherent common-mode detection is proposed. Through judicious arrangement, the common-mode feedback circuit can be economically implemented. On the level of system architectures, a novel filter low-voltage 4th order RF bandpass filter structure based on emulation of two magnetically coupled resonators is presented. A unique feature of the proposed architecture is using electric coupling to emulate the effect of the coupled-inductors, thus providing bandwidth tuning with small passband ripple. As part of a direct conversion dual-mode 802.11b/Bluetooth receiver, a BiCMOS 5th order low-pass channel selection filter is designed. The filter operated from a single 2.5V supply and achieves a 76dB of out-of-band SFDR. A digital automatic tuning system is also implemented to account for process and temperature variations. As part of a Bluetooth transmitter, a low-power quadrature direct digital frequency synthesizer (DDFS) is presented. Piecewise linear approximation is used to avoid using a ROM look-up table to store the sine values in a conventional DDFS. Significant saving in power consumption, due to the elimination of the ROM, renders the design more suitable for portable wireless communication applications.