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[pt] Este trabalho se propõe a examinar as propriedades da Transformada (epsilon) - Herglotz e sua aplicação aos filtros digitais, permitindo explicitar a relação entre módulo e fase da função de transferência de um sistema causal a partir de seu módulo. É apresentada, também, uma extensão da Transformada epsilon - Herglotz Conjugada que permite determinar a característica de módulo da função de transferência de fase é arbitrada. O caso particular da fase linear é estudado, é proposto um algarismo de aproximação e são apresentados exemplos. / [en] This work examines the caracteristics of the epsilon - herglotz Transform and its application to digital filters, leading to the relationship between the magnitude and phase of the transfer function of a causal system from its magnitude function. It also presents an extension of this result to the phase through the definition of a Conjugated epsilon - Herglotz Transfom, which allows the determination of the magnitude characteristic of the transfer function of the causal system when its phase characteristic is given. The special case of the linear phase is analysed, an approximation algorithm is suggested and examples are also presented.

In this paper, the step modulated sine wave [u(t)Asin2πft] response of the low-pass, band-pass, and high-pass filters are evaluated. Butterworth filters from the first order on up to the ideal filter are analyzed, and expressions for the settle times developed. The longest settle time occurs for the ideal filter, with all other filters taking progressively less time to settle as the order decreases. A significant point is that the transient settle time for a filter depends on the difference in applied signal frequency and the filter cut off frequency. The set of expressions developed in this report are primarily intended to be sued in selecting programming time delays in computer based signal measurement and processing systems.

Surface Acoustic Wave (SAW) devices are manufactured using standard metallization and photolithographic techniques that have been established by the semiconductor industry. The facilities in the newly developed Microelectronics laboratory at the University of Central Florida will be utilized in the fabrication of a SAW device. This thesis will outline the complete procedure beginning with the initial design from given specifications, up to mask generation, fabricating and testing of the device. This will serve to calibrate the fabrication process for future work in SAW device and semiconductor fabrication. The models that are used in the SAWCAD design software will be verified by comparing the theoretical and experimental results.

The purpose of this thesis is to formulate a technically sound approach to designing Infinite Impulse Response (IIR) digital filters using high-level modeling tools. High-level modeling tools provide the ability to build and simulate ideal models. Once proper validation is complete on these ideal models, the user can then migrate to lower levels of abstraction until an actual real world model is designed. High-level modeling tools are the epitome of the top-down design concept in which design first takes place with the basic functional knowledge of a system. With each level of abstraction, validation is performed. High-level modeling tools are used throughout industry and their application is continually growing especially in the DSP area where many modes of communications are expanding. High-level modeling tools and validation significantly address this complex expansion by utilizing an ideal representation of a complicated network. / Master of Science

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / The need for precise gain and phase matching in multi-channel data sampling systems can result in very strict design requirements for presample or anti-aliasing filters. The traditional use of active RC-type filters is expensive, especially when performance requirements are tight and when operation over a wide environmental temperature range is required. New Digital Signal Processing (DSP) techniques have provided an opportunity for cost reduction and/or performance improvements in these types of applications. This paper summarizes the results of an evaluation of various digital filter types used as matched presample filters in data sampling systems.

The problem of filtration of liquid aerosols by both wettable and nonwettable filters has been extensively studied and the results of the theoretical calculations together with the experimental results are presented. More realistic models of filtration by both wettable and nonwettable filters have been developed and verified experimentally. A new instrument has been developed, and used in the experiments, for the measurement of the absolute concentration of aerosols in the gas stream. This instrument is based on the measurement of the initial vapour content of the gas stream simultaneously with the measurement of the vapour content after the total evaporation of aerosol. The concentration of the aerosol is calculated as the difference between these two values. The instrument was developed to provide fast and accurate measurements of aerosol concentration. The main advantages of the instrument are: high accuracy, simplicity of measurement, possibility of use for a wide range of substances, perfect suitability of operation for automatic monitoring technologies, etc. All rights for this instrument have been reserved and the fully automatic version will be available in the near future. It was found that the efficiency of filtration of aerosol on the wettable filter depends on the thickness of the liquid film on the fibre. This parameter was taken into account in the development of a theoretical model of filtration on wettable fibrous filters. The particle breakthrough problem has been solved by the optimisation of the aspect ratio (the ratio of the height by width) of the wettable filter. On this basis, industrial devices have been developed, patented, and implemented in industry. These devices provide a stable operating efficiency of higher than 99%. It was found experimentally that the efficiency of filtration of aerosol on the nonwettable filter depends on the diameter of the drop suspended on the filter, and on the area of the filter blocked by drops: this influences the velocity of filtration. All these parameters were taken into account in the development of a theoretical model of filtration on nonwettable fibrous filters. On the basis of this model, satisfactorily verified by the experiments, an industrial device has been developed. The harnessing of atomisers makes it possible to maintain the efficiency of filtration higher than 99%, even with a relatively high velocity of filtration of 2.7m/s. The new technology is tackling the problem of handling huge amounts of exhaust gases and this is particularly important for cramped installations when the space available for the air pollution control technology is quite limited. A highly efficient gas cleaning technology has been developed. This technology is based on combining two stages (wet scrubber and filter) of currently utilised air pollution control devices by submerging the fibrous filter into the liquid on the plate. The new device provides an effective division of the main gas stream into ultra-small bubbles which increase the contact area between the gas and liquid phases. It was estimated theoretically and verified experimentally that the efficiency of the proposed 'combined' technology, is 45% higher than the efficiency of the two stages technology. The technology has been patented and will be offered for industrial implementation in the near future.

<p>Filtri predstavljaju nezaobilazan deo svakog mikrotalasnog uređaja. Skorašnji veoma brz razvoj bežičnih sistema pred mikrotalasne filtre postavlja nove zahteve kao što su visoke performanse, kompaktnost i rad na više proizvoljno odabranih učestanosti koje se mogu nezavisno kontrolisati.<br />Naučni doprinos ove doktorske disertacije predstavlja pet novih konfiguracija mikrotalasnih multi-band filtara koji su realizovani u mikrostrip arhitekturi. Od toga tri konfiguracije predstavljaju dual-band filtre, a preostale dve konfiguracije tri-band filtre. Filtri su realizovani korišćenjem fraktalnih krivih i/ili savijenih &lambda;/4 rezonatora, i to u klasičnoj tehnologiji štampanih ploča i u višeslojnoj tehnologiji nisko-temperaturne zajedno pečene keramike.<br />Detaljno je analiziran i opisan način rada predloženih filtara. Filtri su fabrikovani, a njihove performanse izmerene i upoređene sa drugim rezultatima dostupnim u literaturi. Pokazano je da predložene filtre karakteriše mogućnost nezavisne kontrole propusnih opsega što je iskorišćeno za realizaciju dual-band filtara koji rade na WLAN 2.4/3.5 GHz opsezima i tri-band filtara koji rade na WLAN 2.4/3.5/5.2 GHz opsezima. Štaviše, predložene tri-band strukture predstavljaju najmanje tri-band filtre do danas predložene u literaturi.</p> / <p>Filters are indispensable components in any microwave device. Recent rapid development of wireless systems posed new demands to microwave filters, such as high performance, compact size and the ability to simultaneously operate on several independently selected frequencies.<br />Scientific contribution of this dissertation are five novel microwave multi-band filters realized in microstrip architecture. Out of the five, three configurations are dual-band filters, while the remaining two are tri-band filters. Filters are designed using fractal curves and/or folded &lambda;/4 resonators, in the conventional printed circuits technology or in low-temperature cofired ceramics technology.<br />Operating principles of the proposed filters have been analyzed and explained in detail. Their performances have been measured and compared to other recently published results. It has been shown that the proposed filters allow independent control of the passbands. This has been used to design dual-band filters operating at WLAN frequencies of 2.4/3.5 GHz and tri-band filters operating at WLAN frequencies of 2.4/3.5/5.2 GHz. Moreover, the proposed tri-band filters are the most compact tri-band filters published so far.</p>

The purpose of this paper is to present a new design configuration for multicoupled band-pass filter based on Mason's loop rule, together with the negative feedback topology and to compare it with Leap Frog (LF) and Follow the Leader Feedback (FLF) design examples.