This thesis addresses itself to the solution of a number of problems which arise in the development of Radio Frequency filters, particularly those involving coupled transmission lines as resonant elements. The text is divided into a number of sections dealing with individual topics. After a brief description of Darlington filter design principles, there is an account of the pivotal role of quarter wave sections and their vital part in the realisation of high frequency filters. This is followed by the development of new material relating to equivalent circuits of physical lines in terms of quarter wave sections, and its application to improvements in the design of wide-band filters. There follows an account of a new procedure for calculating the dimensions of comb-line and inter-digital filters. This section includes a new proposal for the inversion of Getsinger's procedure to permit the calculation of rectangular rod dimensions and spacings from given electrical data. There is also an algorithm for use with round rods which circumvents the tedious manual interpolation procedure devised by Cristal. There follows an investigation of and a proposed solution to a long-known but unexplained discrepancy existing between the calculated and measured pass-band width of the class of comb-line filters. With the new procedure the discrepancy reported previously to be of the order of 10% is eliminated. Finally, experimental evidence is adduced to verify the algorithms outlined in the preceding chapters.

Τα φίλτρα λογαριθμικού πεδίου (log-domain filters) είναι μια οικογένεια φίλτρων συνεχούς χρόνου στην οποία γίνεται χρήση της μη-γραμμικής I/V χαρακτηριστικής των ενεργών στοιχείων (BJT τρανζίστορ, MOSFET τρανζίστορ σε ασθενή αναστροφή) για να επιτευχθεί γραμμική συμπεριφορά από είσοδο σε έξοδο. Επιπρόσθετα τα log-domain φίλτρα, προσφέρουν και άλλα πλεονεκτήματα, όπως την ηλεκτρονική ρύθμιση της συχνότητας αποκοπής, την λειτουργία σε υψηλές συχνότητες και την δυνατότητα λειτουργίας με χαμηλή τάση τροφοδοσίας. Στην παρούσα διατριβή προτείνεται μια καινούρια τεχνική σχεδιασμού log-domain φίλτρων, η οποία στηρίζεται στη κυματική μέθοδο (log-domain wave filters). Με αυτή την τεχνική, log-domain φίλτρα μπορούν να σχεδιαστούν είτε με την χρήση των κυματικών παραμέτρων σκέδασης (wave scattering parameters), είτε με την χρήση κυματικών τερματιστών θύρας (wave port terminator). Έτσι αρχικά, προτείνονται δομές log-domain κυματικών φίλτρων με χρήση των κυματικών παραμέτρων σκέδασης. Σε αυτήν την προσέγγιση, το log-domain κυματικό ισοδύναμο ενός επαγωγού σε σειρά κλάδο μετασχηματίζεται από το γραμμικό στο λογαριθμικό πεδίο. Τα log-domain κυματικά ισοδύναμα των υπολοίπων βασικών στοιχείων του παθητικού πρωτοτύπου φίλτρου προκύπτουν από το κυματικό ισοδύναμο του επαγωγού σε σειρά κλάδο με την εναλλαγή των εξόδων του ή/και την προσθήκη αντιστροφέων τάσης. Χρησιμοποιώντας μια διαφορετική προσέγγιση, προτείνονται δομές log-domain κυματικών φίλτρων με χρήση του log-domain κυματικού τερμαστιστή θύρας. Με την χρήση του σχεδιάζεται το κυματικό ισοδύναμο στο log-domain ενός πυκνωτή σε παράλληλο κλάδο, το οποίο χρησιμοποιείται ως το βασικό κυματικό ισοδύναμο δομικό στοιχείο. Τα κυματικά ισοδύναμα των υπολοίπων στοιχείων του παθητικού κυκλώματος προκύπτουν με χρήση των παραπάνω κυματικών ισοδυνάμων. Τέλος γίνεται μελέτη της επίδρασης των μη-ιδανικών χαρακτηριστικών του BJT τρανζίστορ και της επίδρασης των θερμοκρασιακών μεταβολών στην συμπεριφορά των προτεινόμενων φίλτρων, ενώ προτείνονται μέθοδοι τόσο για την επιμέρους όσο και την συνολική αντιστάθμισή τους. / Log-domain filters are a family of continuous time filters that instead of being designed using locally linearized components, directly exploit the non-linear nature of a BJT, or a MOSFET transistor operating in weak inversion, in order to obtain a system with overall linear performance. This way they exhibit high linearity even for large signal to bias ratios. In addition they have some other interesting features like tunability and the ability to work at high frequencies even with low voltage supplies. In the present dissertation a new method for the design of log-domain filters is proposed, based on the well-known wave method. According to this method log-domain filters can be designed using the wave scattering parameters or using the wave port terminator block. Structures of log-domain wave filters using wave scattering parameters are initially proposed. In this approach the log-domain wave equivalent of a series inductor is transformed from linear to log-domain. Log-domain wave equivalents of the other basic elements of a passive prototype are then derived by the interchange of its outputs or/and the addition of voltage inverters. These equivalents are then connected together forming the actual filter. Log-domain differential wave filters can be designed by the introduction of the log-domain differential wave equivalent of the series inductor. Using a different approach, log-domain wave filters have been designed, introducing the block of a log-domain wave port terminator. Using this block, the log-domain wave equivalent of a shunt capacitor is derived as the based structure element. The wave equivalents of other basic elements of the passive prototype are derived as before interchanging its outputs or/and adding voltage inverters. Finally the influence of the non-ideal characteristics of the BJT transistor on the frequency response of the derived filters is analyzed and efficient methods are proposed for their compensation.

This thesis is focused on the microprocessor-controlled frequency filter project. The main goal of the thesis is to present basic terms and principles of frequency filters and active frequency filters for cascading synthesis. Furthermore, the work contains information on digital potentiometers. The thesis includes circuit simulations and a project of connecting with a printed circuit board. The last chapter contains the results of the measurements.

Cette thèse porte sur la conception d'un circuit intégré CMOS pour l'électronique de lecture de capteurs bolométriques à base de semiconducteurs ou supraconducteurs haute-température. Dans ce manuscrit, une chaîne de traitement du signal est étudiée. Elle est composée d'un amplificateur différentiel à gain fixé pour des températures de 40 à 400K, ainsi que d'un filtre de fréquence passe-bas actif à haute dynamique. Une architecture optimale d'amplificateur est définie sans contre-réaction, permettant d'atteindre une large bande passante (17MHz pour un gain de 40dB), une consommation réduite (Iq = 2mA) et une haute impédance d'entrée. Afin de fixer le gain avec précision dans la structure CMOS, deux méthodes différentes sont présentées et vérifiées sur un circuit intégré. Par la suite, le comportement des filtres dans la bande d'atténuation est étudié afin d'augmenter la fréquence de coupure maximale. Deux structures avec une faible influence des éléments actifs « réels » sont conçues: le filtre Sallen-Key amélioré et la structure basée sur un convoyeur du courant CCII-. Enfin, nous présentons un CCII- intégré en CMOS ayant une très faible impédance de sortie.

Práce se zabývá adaptivními filtry pro vizualizaci obrazů s vysokým rozlišením. V teoretické části je popsán princip činnosti konfokálního mikroskopu a matematicky korektně zaveden pojem digitální obraz. Pro zpracování obrazů je volen jak frekvenční přístup (s využitím 2-D a 3-D diskrétní Fourierovy transformace a frekvenčních filtrů), tak přístup pomocí digitální geometrie (s využitím adaptivní ekvalizace histogramu s adaptivním okolím). Dále jsou popsány potřebné úpravy pro práci s neideálními obrazy obsahujícími aditivní a impulzní šum. Závěr práce se věnuje prostorové rekonstrukci objektů na základě jejich optických řezů. Veškeré postupy a algoritmy jsou i prakticky zpracovány v softwaru, který byl vyvinut v rámci této práce.

This diploma thesis is concentrated to fully differential and non-differential fractional-order filters with active elements. It describes how we can obtain fractional-order fully-differential filters design from non-differential design, thesis describes realization in OrCad program and simulation of this project. The first part of the thesis concerns theoretical analysis of frequency filters, active elements and fractional-order filters. The second part of the thesis includes designs of filters and simulations of differential structures and rest of non-differential structures simulation. The following part of the thesis concerns practical realization and experimental measurment of differential fractional-order filter. In the last part of this project, thesis evaluates all results which were revealed in our simulations and experimental measurment.

Práce se zabývá adaptivními filtry pro vizualizaci obrazů s vysokým rozlišením. V teoretické části je popsán princip činnosti konfokálního mikroskopu a matematicky korektně zaveden pojem digitální obraz. Pro zpracování obrazů je volen jak frekvenční přístup (s využitím 2-D a 3-D diskrétní Fourierovy transformace a frekvenčních filtrů), tak přístup pomocí digitální geometrie (s využitím adaptivní ekvalizace histogramu s adaptivním okolím). Dále jsou popsány potřebné úpravy pro práci s neideálními obrazy obsahujícími aditivní a impulzní šum. Závěr práce se věnuje prostorové rekonstrukci objektů na základě jejich optických řezů. Veškeré postupy a algoritmy jsou i prakticky zpracovány v softwaru, který byl vyvinut v rámci této práce.

Additive manufacturing (AM) is an attractive way to shorten development time, reduce product weight and allow the manufacturing of more complex products than by conventional manufacturing processes. The problem arises when the previous traditional manufacturing requirements need to be fulfilled by AM as well as the volume production capability. This investigation is done together with Ericsson to evaluate the possibilities of the different AM technologies, post-processing methods and silver coating processes to guarantee the specifications of radiofrequency (RF) filters. Here, minimal RF signal insertion losses are targeted. Since insertion losses are dependent on surface roughness, surface smoothness is sought as well. Ericsson simulation software uses correction factors to account for surface roughness, however there are some inconsistencies between the simulated and actual surface roughness that is allowed in the parts. In AM parts, surface roughness is not easy to control since it depends on parameters related to feedstock, process and machine properties. Commonly, most AM components do not comply with requirements of lower surface roughness values. Therefore, parts need to be smoothened before silver plated; this step is necessary to ensure the electrical conductivity in this specific application. These finishing processes add costs to the final product and increase time to market. Firstly, a comprehensive study was carried out to better understand the landscape of AM technologies, postprocessing and silver coating methods. Secondly, the different processes are assessed with the help of selection matrices, considering the products requirements. The components to print are two RF filters with different shapes and dimensions but similar requirements. The CAD design is modified depending on each AM process and directly affects the results. Afterwards, the design of an experimental plan is carried out; the number of samples of each part comparing AM technologies, feedstock, different suppliers (3D printing and post-processing) is obtained. Due to budget and time restrictions, the parts were printed using Multi Jet Fusion and Selective Laser Melting processes. After printing, tolerances and surface roughness were measured. This thesis results in the selection of suitable AM technologies and post-processing methods for RF filters. For MJF printed cavities at 0˚, 30˚ and 90˚ orientation, the best results for this application are obtained at 30˚ providing a good balance between sharp detail and smooth surfaces. In the case of SLM, waveguides are printed at 0˚ and 30˚. 30˚ waveguides present lower surface roughness values than the 0˚ ones as inner support material is needed at 0˚ orientation. SLM cavities were printed at 30˚ in seek of asymmetry between faces, resulting in higher surface roughness in the downfacing face.

The aim of master's thesis was design of electronically reconfigurable filters. Adjustability of pole frequency or quality factor is possible. First part of thesis deals with theoretical analysis of filters, their operation modes, design of frequency filters using Signal-Flow graph method and parasitic analysis. The next part describes active elements used in thesis. In a third part, three reconfigurable filters are described and designed and their simulations and parasitic analysis are made. Last part deals with filter design in EAGLE and experimental measurement.

Master’s thesis deals with the issue of electronic filtering circuits with arbitrary frequency characteristics. First part of the thesis describes theoretical basis. Second part explores the possibilities of design procedures for filters with arbitrary frequency characteristics. Design procedures are demonstrated on examples accordingly to the presented methods, including their circuit implementation and computer simulation to verify the correctness of theoretical assumptions. Thesis also explores the possibilities of tuning circuit structures and electronic setting for characteristics using controllable active elements.