Variable attenuators are important circuits that can be employed in many radio frequency (RF) applications, e.g., in automatic gain control (AGC) amplifiers, broadband gain-control blocks at RF frequencies or as broadband vector modulators. For any applications, low insertion phase shift and low power consumption are of interest. A way to implement variable attenuators is using the RF PIN diode. The PIN diode is characterized by a low doped (I = intrinsic) semiconductor region between p- (P) and n-type (N) semiconductor regions. Besides the variable attenuators, the PIN-diode is used in other RF circuits, such as RF switches, limiters and phase shifters. This project presents the design of variable attenuators at 7.5 GHz and 500 MHz frequency bandwidth for ultra-wideband (UWB) applications using two different PIN diodes. The variable attenuators have a topology based on 90° hybrid couplers. The design is performed using Advance Design Systems (ADS) from Agilent Technologies Inc. After presenting the PIN diode and its equivalent circuit, the theory of the 90° passive directional branch line coupler and the operation principle of the variable attenuators are presented. As the selection of the appropriate PIN diode is a critical step in the design, special attention is dedicated to this aspect. It follows the design of the variable attenuators with extensive descriptions of the simulations in ADS. Firstly, both series and shunt attenuators are presented. However, as these circuits normally offer narrow band variable attenuation, the 900 directional branch line coupler is used in the attenuator for broader band operation. At the end, a double hybrid coupler is found to eliminate the ripple in the high attenuation state of the single hybrid coupled attenuator. So the final topology of the variable attenuator is a double hybrid coupler variable attenuator- Moreover, in this project, different PIN diodes are investigated for variable attenuator applications. Different manufacture companies are currently providing different kinds of PIN diodes in terms of parameters and packages. Every type of PIN diodes are providing different sort of advantages to the designers. That is why it has become more difficult for the RF designers to choose the right device for the specified application. Beside the design of the variable attenuator using PIN diodes, some considerations in form of a guide line to the designers while they are using the PIN diode for designing the variable attenuator. In this work, the used PIN diodes are a beam lead PIN diode and chip PIN diode. The beam lead PIN diode is used because it is manufactured for high frequency and it produces excellent electrical performance and isolation at high frequencies. On the other hand, the chip PIN diode eliminates the problem of package parasitics. However, printed circuit board (PCB) manufacturing limitations at the university laboratory incline the balance in the favor of the beam lead PIN diode, HPND- 4005 from Avagotech, instead of the also considered chip diode MA-COM MA4P202.

No description available.

In the early 80’s it was recognized that electronic data mining is a serious threat to the autonomity of persons and PIN became a symbol of total citizen control. There appeared a need to consider either the priority of technical advancements or the priority of human rights. This is why precise legal provisions about using the PIN appeared. The use of PIN became a requirement and this process began even in those countries where PIN had been already introduced before the rise of overwhelming concern about data protection. It can be noted that the regulation of the use of personal number is not fully comprehensive, despite the fact that the European Convention for the Protection of Human Rights and Fundamental Freedoms enacted by the Council of Europe in 1950, where the right to privacy is provisioned as one of the most significant rights, established an efficient human rights implementation mechanism. The countries employing the PIN of specific context acquire the information about a part of life of the individual and not violate the individual privacy. The countries, employing universal multifunctional identity identificators have established a high level control measures. However, in any case when the confirmation of a person’s identity is needed, it is advisable to authentificate his/ her existing features disclosing only a minimum content of private personal data. In other words, the disclosure of private personal data should be in proportion with the main objectives of... [to full text]

Thèse (M.Sc. )--Université Laval, 2007. / Titre de l'écran-titre (visionné le 5 mai 2008). Bibliogr.

Akademisk avhandling--Uppsala. / Summary in English. Bibliography: p. 103-108.

Thèse (M.Sc.)--Université Laval, 2004. / Bibliogr.: f. 44-51. Publié aussi en version électronique.

Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 27, 2007) Includes bibliographical references.

Techn. Universiẗat, Diss., 2004--Dresden.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Economia, Administração e Contabilidade, Departamento de Administração, 2016. / Submitted by Camila Duarte (camiladias@bce.unb.br) on 2017-01-24T15:58:32Z No. of bitstreams: 1 2016_LeonardoMeloBosque.pdf: 6077809 bytes, checksum: 18ba231fecce38d5446c0ce62dec4f98 (MD5) / Rejected by Ruthléa Nascimento(ruthleanascimento@bce.unb.br), reason: Altere o título e o nome do orientador, por favor. Obrigada! on 2017-02-15T17:08:17Z (GMT) / Submitted by Camila Duarte (camiladias@bce.unb.br) on 2017-02-16T11:21:08Z No. of bitstreams: 1 2016_LeonardoMeloBosque.pdf: 6077809 bytes, checksum: 18ba231fecce38d5446c0ce62dec4f98 (MD5) / Approved for entry into archive by Ruthléa Nascimento(ruthleanascimento@bce.unb.br) on 2017-03-30T13:20:03Z (GMT) No. of bitstreams: 1 2016_LeonardoMeloBosque.pdf: 6077809 bytes, checksum: 18ba231fecce38d5446c0ce62dec4f98 (MD5) / Made available in DSpace on 2017-03-30T13:20:03Z (GMT). No. of bitstreams: 1 2016_LeonardoMeloBosque.pdf: 6077809 bytes, checksum: 18ba231fecce38d5446c0ce62dec4f98 (MD5) / Um dos modelos mais populares na mensuração da assimetria de informação de ativos financeiros consiste no modelo da probabilidade de informação privilegiada (PIN) proposto por Easley et al. (1996b). O seu embasamento teórico bem como sua ampla possibilidade de aplicação, tornaram da PIN um benchmark para a verificação da existência de insider trading em transações financeiras. Tendo em vista a facilidade de interpretação da PIN e de seus parâmetros, este estudo objetiva avaliar e propor o cálculo da probabilidade de informação privilegiada por meio de inferência bayesiana. Tal abordagem traz a possibilidade de agregar opiniões de especialistas sobre os parâmetros da PIN e apresenta contribuições inéditas para o escopo teórico de modelos de microestrutura de mercado. / One of the most popular models for measuring information asymmetry of financial assets is the probability of informed trading model (PIN) proposed by Easley et al. (1996b). Its theoretical foundation and its wide possibility of application, made PIN a benchmark on insider trading studies. In view of the interpretability of PIN and its parameters, this study aims to evaluate and propose a bayesian version for the probability of informed trading model. Such approach brings the possibility to include expert opinions about the PIN parameters and represents a new contribution to the theoretical scope of market microstructure models.

Neste trabalho foram processados e caracterizados dispositivos emissores de luz (LED’s) baseados em estruturas p-i-n a partir de filmes de GaAs dopados unicamente com Silício e crescidos através da técnica de Epitaxia de Feixes Moleculares sobre substratos de GaAs orientados nas superfícies (311)A e (211)A. Nas superfícies (311)A e (211)A, o Si tem comportamento anfótero, ou seja, pode ocupar tanto o sítio do Ga como o do As, o que resulta em filmes com portadores tipo n e p, respectivamente. As características elétricas dos filmes dependem das seguintes condições de crescimento: i) razão entre os fluxos de Ga e As; e ii) temperatura do substrato. As técnicas de caracterização utilizadas foram fundamentalmente: Fotoluminescência, IxV (corrente-tensão) e Efeito Hall. Os dispositivos p-i-n foram processados a partir de técnicas convencionais de fotolitografia e caracterizados a partir das técnicas de IxV e Eletrolumi-nescência. Os dispositivos estudados foram produzidos a partir de camadas de GaAs e AlGaAs crescidas nas direções [311]A e [211]A. Os dispositivos obtidos a partir de filmes dopados de GaAs apresentaram uma boa eficiência de emissão, porém foram observadas perdas ôhmicas ocasionadas pela natureza da junção obtida nestes planos, ocasionada por defeitos, principalmente nos filmes dopados tipo n que são crescidos em condições extremas de temperatura e pressão de Arsênio. Os dispositivos a base de AlGaAs apresentaram baixa eficiência e altas perdas, relacionadas com a alta compensação apresentada pelos filmes. Foram testados também dispositivos com heteroestruturas na camada intrínseca, apresentando resultados satisfatórios.