Continuous-time cascaded ΣΔ modulators for VDSL: A comparative study

This paper describes new cascaded continuous-time ΣΔ modulators intended to cope with very high-rate digital subscriber line specifications, i.e 12-bit resolution within a 20-MHz signal bandwidth. These modulators have been synthesized using a new methodology that is based on the direct synthesis of the whole cascaded architecture in the continuous-time domain instead of using a discrete-to-continuous time transformation as has been done in previous approaches. This method allows to place the zeroes/poles of the loop-filter transfer function in an optimal way and to reduce the number of analog components, namely, transconductors and/or amplifiers, resistors, capacitors and digital-to-analog converters. This leads to more efficient topologies in terms of circuitry complexity, power consumption and robustness with respect to circuit non-idealities. A comparison study of the synthesized architectures is done considering their sensitivity to most critical circuit error mechanisms. Time-domain behavioral simulations are shown to validate the presented approach.Ministerio de Educación y Ciencia TEC2004-01752/MI

A design tool for high-resolution high-frequency cascade continuous- time Σ∆ modulators

Event: Microtechnologies for the New Millennium, 2007, Maspalomas, Gran Canaria, SpainThis paper introduces a CAD methodology to assist the de signer in the implementation of continuous-time (CT) cas- cade Σ∆ modulators. The salient features of this methodology ar e: (a) flexible behavioral modeling for optimum accuracy- efficiency trade-offs at different stages of the top-down synthesis process; (b) direct synthesis in the continuous-time domain for minimum circuit complexity and sensitivity; a nd (c) mixed knowledge-based and optimization-based architec- tural exploration and specification transmission for enhanced circuit performance. The applicability of this methodology will be illustrated via the design of a 12 bit 20 MHz CT Σ∆ modulator in a 1.2V 130nm CMOS technology.Ministerio de Ciencia y Educación TEC2004-01752/MICMinisterio de Industria, Turismo y Comercio FIT-330100-2006-134 SPIRIT Projec

Effect of Clock Jitter Error on the Performance Degradation of Multi-bit Continuous-Time ΣΔ Modulators With NRZ DAC

This paper analyses the effect of the clock jitter error in multi-bit continuous-time ΣΔ modulators with non-return-to-zero feedback waveform. Derived expressions show that the jitter-induced noise power can be separated into two main components: one that depends on the modulator loop filter transfer function and the other one due to the input signal parameters, i.e amplitude and frequency. The latter component, not considered in previous approaches, allows us to accurately predict the resolution loss caused by jitter, showing effects not taken into account up to now in literature which are specially critical in broadband telecom applications. Moreover, the use of state-space formulation makes the analysis quite general and applicable to either cascade or single-loop architectures. Time-domain simulations of several modulator topologies intended for VDSL application are given to validate the presented analysis.Ministerio de Educación y Ciencia TEC2004-01752/MIC, TIC2003-0235

Post-Franco Theatre

In the multiple realms and layers that comprise the contemporary Spanish theatrical landscape, “crisis” would seem to be the word that most often lingers in the air, as though it were a common mantra, ready to roll off the tongue of so many theatre professionals with such enormous ease, and even enthusiasm, that one is prompted to wonder whether it might indeed be a miracle that the contemporary technological revolution – coupled with perpetual quandaries concerning public and private funding for the arts – had not by now brought an end to the evolution of the oldest of live arts, or, at the very least, an end to drama as we know it

Una Contribución al Diseño de Moduladores Sigma-Delta en Cascada Realizados Mediante Técnicas de Circuito en Tiempo Continuo

Esta tesis doctoral es el resultado de un conjunto de trabajos de investigación encaminados a sistematizar y optimizar el diseño de convertidores analógico-digitales de tipo Sigma-Delta (), realizados mediante técnicas de circuito en tiempo continuo. Pa

Benito Pérez Galdós

In Galdós\u27 time, the tensions between such diverse phenomena as coins and credit, free trade and protectionist tariffs, factory work and domestic economy, masculine and feminine, and private and public exacerbated friction among peoples—those of pueblo and rural origins, whose voices rasped and whose bright colors raked the eye, and a nascent, insecure bourgeosie who, fearful of the masses, strove to imitate the aristocracy. Old and new converged also with the question of suffrage and citizenship to aggravate social malaise and political upheavals—Carlist wars, palace intrigues, the Revolution of 1868 and overthrow of Queen Isabel, the brief reign of Amadeo of Savoy, the aborted First Republic and the Bourbon Restoration (1875-1885), which reached Spain from England in the imported person of Alfonso XII. These turbulent events undergird the cultural, historical, and political events of the novels by Benito Pérez Galdós (1843–1920) to be discussed in this chapter. Galdós is the author of seventy-seven novels, twenty-six original plays, and numerous occasional pieces, written between 1867 and 1920. These divide into two main categories: the historical and the contemporary social novels, now more appropriately described as novels of modernity The forty-six historical novels, called Episodios nacionales, make up five series, each consisting of ten interconnected novels, except the fifth series, left unfinished. The thirty-one novels of modernity, published between 1870 and 1915, also divide into two groups: Novelas de la primera época ( Novels of the Early Period, 1870–1879) and Las novelas de la serie contemporánea ( The Contemporary Social Novels, 1881–1915). The novels of the early period comprise Galdós\u27 first attempts at novel writing, as well as four so-called thesis novels : Doña Perfecta (1876), the sequel Gloria (1876–1877), Marianela (1878), and La familia de León Roch ( The Family of León Roch, 1878–1879). The next group of novels represents what Galdós called his segunda manera —his second style, a different kind of writing ... a more sophisticated and varied mode of narrative presentation