Foram encontradas 50 questões.
Supondo que um multiplexador possua 16 entradas de sinal, o número de entradas de seleção necessárias, excluindo a entrada ENABLE (habilita), é igual a
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Considere a ROM (Read Only Memory) abaixo. Assinale a alternativa que NÃO contém uma palavra armazenada na ROM representada:
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Sobre a fabricação de um transistor nMOS (Metal-Óxido-Semicondutor tipo “n”), pode-se afirmar que a seguinte etapa desse processo é dita auto-alinhada:
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Alguns anéis de pad existentes nas entradas de dispositivos CMOS (Metal-Óxido-Semicondutor Complementar) contêm implementações de Schmitt triggers, cuja histerese eleva o ponto de chaveamento quando o sinal de entrada é baixo e o reduz quando o sinal de entrada é alto. A função desse circuito nessas estruturas é
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Seja um transistor nMOS (Metal-Óxido-Semicondutor tipo “n”) em um processo de 0,6 μm com espessura do óxido da porta de 10 nm. A concentração de dopantes aceitadores de carga NA é igual a 5 x 1018 cm-3 e a tensão de limiar nominal é igual a 5 V. Se tensão da fonte for igual a 440 mV, a variação na tensão de limiar à temperatura ambiente será igual a:
(Considere os seguintes parâmetros: permissividade do vácuo ε0 = 8,85 x 10-14 F/cm; permissividade absoluta do óxido εox = 4ε0; permissividade absoluta do silício εSi = 88,5ε0; carga elétrica elementar q = 1,6 x 10-19 C; tensão térmica VT = 25 mV e concentração intrínseca de portadores de carga ni = 1010 cm-3 à temperatura ambiente. Considere, ainda, para os cálculos que: ln 5 = 1,6 e ln 10 = 2,3.)
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Um mecanismo de falha de inversores CMOS (Metal-Óxido-Semicondutor Complementar) caracteriza-se pela formação de um retificador controlado de silício (SCR) biestável a partir do acoplamento cruzado de transistores “npn” e “pnp” parasitas, desenvolvendo caminhos de baixa resistência entre o dreno e o corpo dos inversores que normalmente são aterrados. É, então, estabelecida uma malha de realimentação que faz circular uma corrente elevada entre o dreno e o corpo, resultando no desligamento da fonte de alimentação ou no derretimento dos terminais de alimentação. Tal mecanismo de falha denomina-se:
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O software Virtuoso Hierarchy Editor permite ao usuário visualizar vários níveis de um único projeto usando uma tabela ou uma vista em árvore.
Assinale uma alternativa que NÃO é passível de ser executada pelo Virtuoso Hierarchy:
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Em um dispositivo semicondutor, o movimento dos portadores de carga por deriva deve-se
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O trecho que segue foi extraído do conto “Lâmpadas e Ventiladores”, de Humberto de Campos:
A tarde estava quente, abafada, ameaçando tempestade. Na sala da sorveteria onde tomávamos chá, os ventiladores ronronavam, como gatos, refrescando o ambiente. Lufadas ardentes, fortes, brutais, varreram, lá fora, o asfalto da Avenida. O céu escureceu, de repente, e um trovão estalou, rolando pelo céu. Nesse momento, as lâmpadas do salão, abertas àquela hora, apagaram-se todas, ao mesmo tempo em que, dependendo da mesma corrente elétrica, os ventiladores foram, pouco a pouco, diminuindo a marcha, até que pararam, de todo, como aves que acabam de chegar de um grande voo.
Sobre a tipologia textual dessa passagem do conto, pode-se dizer a organização predominante é
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TEXT
Emerging markets: a bubble that has finally burst?
Patrick Collinson, guardian.co.uk, Friday 5 August 2011
One of Britain's most successful fund managers has warned about an emerging market bubble and told small investors, who have poured billions of pounds into emerging market funds, that returns could be sorely disappointing over the next few years.
British investors now hold more than £40bn in emerging market funds – typically invested in China, Brazil and India – and those who jumped in early have done well. The average fund invested in China has made a 112% gain since 2006 while the very best fund, run by First State, has notched up a breathtaking 159% gain for its investors. Meanwhile, the average fund invested in UK shares has limped in with a rise of 18% over the same period.
But last week the head of global emerging market equities at First State, Jonathan Asante, told investors that the good times may be over. Asante wrote to investors saying that most stocks in emerging markets are "fully valued", which in fund manager speak means he believes that they are not worth investing in and could be headed for a fall. A formal warning to investors from their fund manager is extremely rare, as it could prompt investors to bolt for the exit – and shrink the funds from which they are paid.
Asante takes a longer view than most of his rivals. Profit sharing and bonuses at First State are only paid out on the basis of three-year numbers rather than quarterly or half-yearly figures. Managers are also required to put most of their personal wealth into their funds. "It means that managers have to eat their own cooking," he says.
Asante, who used to teach at the London School of Economics before becoming a fund manager, is not forecasting an abrupt halt to the Chinese economic miracle, or an end to India's growth. But he says that so much money has flooded into the shares of emerging market companies that even the best of them may now be overvalued. Many companies command share price ratings which are a multiple of their equivalents in the west, he says, yet are trading in areas where corruption is rife, inflation rising, where legal systems are immature and where back-door state control is common.
Overvaluations are perhaps most severe in Latin America, particularly Brazil, he says. Indeed, he was so concerned that last December he wrote a separate warning note to clients in his Latin American portfolios. It was a good call – the São Paulo Bovespa index was then around 70,000, and is now around 56,000. He continues to believe that the Brazilian currency, the real, is the "most ridiculously over-valued currency in the world".
It is telling what First State managers are doing with their own cash tied up in First State funds. They now only have around 60% in equity funds, with 40% in cash (sterling, Hong Kong dollar and Singapore dollar) and gold.
"The world is a very risky place right now. I would have to be sceptical of the China story. The central planners have in some senses been wonderful at balancing growth, inflation, banking and environmental concerns. I applaud them but wonder if they can keep this going forever."
However, Asante's views are not shared by the majority of emerging market fund managers. In contrast, the manager of another giant emerging markets fund, Michael Konstantinov, of the £870m Allianz RCM Bric Stars fund, this week told potential investors that valuations are currently "very cheap" (his italics) and that they offer an "outstanding entry point".
"I think it is important to remind ourselves that the Bric [Brazil, Russia, India, China] countries came through the global economic crisis of 2008 and 2009 quite well. Brazil did not even go into recession in 2009 while India and China continued to grow very strongly in the range of 8%-9%. Only Russia had a short-term setback, but has recovered well and is, again, leading the global growth dynamic.
"As the demand side of these economies is mainly driven by domestic demand, not by exports, they are more resilient to a global crisis."
Fidelity, which took more than £500m from UK investors into a China fund launched by its most high-profile manager, Anthony Bolton, has struggled to make money for them yet. The trust is currently trading at 96p compared to its launch price of 100p in April 2010, although Fidelity remains bullish on the region.
Nick Price, manager of Fidelity Emerging Markets fund and the Fidelity EMEA fund, says: "As an emerging market fund manager you'd expect me to be bullish wouldn't you? Clearly, many of the markets are facing headwinds right now and these may last for some months. But having just come back from China where I spent a week visiting 30 companies, I remain convinced that the China consumer story is as strong as ever.
"On a longer-term basis, emerging market stocks represent a fraction of their potential worth. It's a strong statement I know, but look at the facts. Emerging markets represent 90% of the world's oil reserves, over 80% of the world's population, over 60% of the world's forex reserves, 30% of global GDP, but yet are only 13% of global stock market capitalisation. I am convinced that the longer you look out, the more sure you can be that emerging markets offer great opportunities."
(source: http://www.guardian.co.uk/money/2011/aug/05/emerging-markets-bubble-burst)
According to Text, the meaning conveyed by the question “a bubble that has finally burst?” is:
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