Matrix Methods for the Dynamic Range Optimization of Continuous-TimeGm-CFilters

This paper presents a synthesis procedure for the optimization of the dynamic range of continuous-time fully differential G m - C filters. Such procedure builds up on a general extended state-space system representation which provides simple matrix algebra mechanisms to evaluate the noise and distortion performances of filters, as well as, the effect of amplitude and impedance scaling operations. Using these methods, an analytical technique for the dynamic range optimization of weakly nonlinear G m - C filters under power dissipation constraints is presented. The procedure is first explained for general filter structures and then illustrated with a simple biquadratic section

A 0.18 μm CMOS low noise, highly linear continuous-time seventh-order elliptic low-pass filter

This paper presents a fast procedure for the system-level evaluation of noise and distortion in continuous-time integrated filters. The presented approach is based on Volterra's series theory and matrix algebra manipulation. This procedure has been integrated in a constrained optimization routine to improve the dynamic range of the filter while keeping the area and power consumption at a minimum. The proposed approach is demonstrated with the design, from system- to physical-level, of a seventh-order low-pass continuous-time elliptic filter for a high-performance broadband power-line communication receiver. The filter shows a nominal cut-off frequency of fc = 34MHz, less than 1dB ripple in the pass-band, and a maximum stop-band rejection of 65dB. Additionally, the filter features 12dB programmable boost in the pass-band to counteract high frequency components attenuation. Taking into account its wideband transfer characteristic, the filter has been implemented using G m-C techniques. The basic building block of its structure, the transconductor, uses a source degeneration topology with local feedback for linearity improving and shows a worst-case intermodulation distortion of -70 dB for two tones close to the passband edge, separated by 1MHz, with 70mV of amplitude. The filter combines very low noise (peak root spectral noise density below 56nV/√Hz) and high linearity (more than 64dB of MTPR for a DMT signal of 0.5Vpp amplitude) properties. The filter has been designed in a 0.18μm CMOS technology and it is compliant with industrial operation conditions (-40 to 85°C temperature variation and ±5% power supply deviation). The filter occupies 13mm2 and exhibits a typical power consumption of 450 mW from a 1.8V voltage supply.Ministerio de Ciencia y Tecnología TIC2003-0235

System-level optimization of baseband filters for communication applications

In this paper, a design approach for the high-level synthesis of programmable continuous-time baseband filters able to achieve optimum trade-off among dynamic range, distortion behavior, mismatch tolerance and power area consumptions is presented. The proposed approach relies on building programming circuit elements as arrays of switchable unit cells and defines the synthesis as a constrained optimization problem with both continuous and discrete variables, this last representing the number of enabled cells of the arrays at each configuration. The cost function under optimization is, then, defined as a weighted combination of performance indices which are estimated from macromodels of the circuit elements. The methodology has been implemented in MATLAB™ and C++, and covers all the classical approximation techniques for filters, most common circuit topologies (namely, ladder simulation and cascaded biquad realizations) and both transconductance-C (Gm-C) and active-RC implementation approaches. The proposed synthesis strategy is illustrated with a programmable equal-ripple ladder Gm-C filter for a multi-band power-line communication modem.P.R.O.F.I.T. FIT-070000-2001-84

A 0.18μm CMOS low-noise elliptic low-pass continuous-time filter

This paper presents a seventh order low-pass continuous-time elliptic filter for use in a high-performance wireline communication receiver. As an additional attribute, the filter provides programmable boost in the pass-band to counteract high frequency components attenuation. The filter shows a nominal cutoff frequency of fc=34 MHz , less than 1dB ripple in the pass-band, and a maximum stop-band rejection of 65dB. The filter also exhibits low noise feature (peak root spectral noise density below 56nV√Hz) and high linearity (more than 64dB of MTPR for a DMT signal of 0.5Vpp amplitude). It has been designed in a 0.18μm CMOS technology and it is compliant with industrial operation conditions (-40 to 85° C temperature variation and ± 5% power supply deviation). Simulations show a typical power consumption of 450 mW @ 1.8V supply.Ministerio de Ciencia y Tecnología TIC2003-0235

A revision of Supo L. and Nassella Desv. (Poaceae) genera in Iberian Peninsula and Balearic

A revision of Supo L. and Nassella Desv. (Poaceae) genera in Iberian Peninsula and Balearic Islands.. A taxonomic study of the genus Stipa L. and Nassella Desv. at the Iberian Penisula has been made. 27 taxa of the genus Stipa are recognized, 18 of which are species and the remaining infraspecific taxa. Nassella mucronata is the only species of the genus Nassella in the studied area. Keys to identification of the taxa are given, together with descriptions, the most important synonimies and information concerning to their cromosomic numbers and geographical distribution. Eight combinations have been made: Stipa sect. Inaequiglumes, Stipa sect. Jarava, Stipa sect. Macrochloa, Stipa sect. Giganteae, S. iberica var. austro-iberica, S. iberica var. pseudodasyphylla, S. parviflora var. pilosa and S. pauneroana. The following taxa are new : S. apertifolia var. nevadensis, S. juncea var. cabanasii y S. gigantea subsp. donyanae.Revisión del género Supo L. y Nassella Desv. (Poaceae) en la Peninsula Ibérica e Islas Baleares. Se ha efectuado un estudio taxonómico de los géneros Stipa L. y Nassella Desv. en la Península Ibérica e Islas Baleares. Para el primero se reconocen en el territorio 27 taxones: 18 especies y el resto taxones infraespecíficos, mientras que el segundo está representado sólo por N. mucronata. Se aportan claves para la identificacion de los taxones, que se acompañan además de descripción, principales sinonimias comprobadas e información sobre su número cromosómico y distribución en el territorio. Se efectúan ocho combinaciones: Supo sect. Inaequiglumes, Stipa sect. Jarava, Stipa sect. Macrochloa, Stipa sect. Giganteae, S. iberica var. pseudodasypkylla, S. iberica var. austro-iberica, S. parvtflora var. pilosa y S. pauneroana, y se describen ademas los siguientes taxones S. apernfolia var. nevadensis, S. juncea var. cabanasii y S. gigantea subsp. donyanae

The Bartle Bilinear Integration and Carleman Operators

AbstractSome characterizations of integrable functions in the bilinear sense of Bartle with respect to the injective tensor product are obtained. As a consequence it is shown that the kernels of Carleman compact operators coincide with these Bartle integrable functions. This result is applied to prove that every Carleman L-weak-compact operator is compact. An example showing the different behavior of the integrability with respect to the projective tensor product is given. A general Fubini theorem in this setting is shown

Delimiting coastal zones for integrated management: The case of the island and the sea of Chiloé (Chile)

A delimitation of coastal areas based on an integrated approach has not yet been proposed in Chile. In response, the objective of this research is to propose a definition of coastal zones on a subregional scale, specifically in the archipelagic environment of the island and the sea of Chiloé, a highly unique geographic area where most globally observable coastal dilemmas converge. The methodology used, which is based on the Integrated Coastal Zone Management's (ICZM) principles, consisted of the analysis of multiple criteria grouped into five typologies: ecological, socioeconomic, cultural, political-administrative, and arbitrary. It is therefore the first delimitation of these characteristics proposed not just for the far south of Chile, but for the entire country. The coastal area that was delimited and mapped exceeds the conventional borders of the provincial district of Chiloé. The totality of islands and the inland sea has been included, in addition to other continental and open sea areas. The results have been divided into the four aspects of the field to achieve a more detailed justification of the suggested criteria. This example could serve as the study object for a future ICZM Program in Chiloé, an instrument that has not been developed to date. In addition, considering the territorial complexity that characterizes the archipelagic environment studied, the methodological proposal could be repeated in other coastal areas in the country. © 2023 The Author

Imaging Biomarkers for the Diagnosis and Prognosis of Neurodegenerative Diseases. The Example of Amyotrophic Lateral Sclerosis

The term amyotrophic lateral sclerosis (ALS) comprises a heterogeneous group of fatal neurodegenerative disorders of largely unknown etiology characterized by the upper motor neurons (UMN) and/or lower motor neurons (LMN) degeneration. The development of brain imaging biomarkers is essential to advance in the diagnosis, stratification and monitoring of ALS, both in the clinical practice and clinical trials. In this review, the characteristics of an optimal imaging biomarker and common pitfalls in biomarkers evaluation will be discussed. Moreover, the development and application of the most promising brain magnetic resonance (MR) imaging biomarkers will be reviewed. Finally, the integration of both qualitative and quantitative multimodal brain MR biomarkers in a structured report will be proposed as a support tool for ALS diagnosis and stratification

The World Heritage Convention and cultural landscapes of the enlightened Spanish Royal Arsenals: The case of the Royal Arsenal of Cartagena (Spain)

In 1992 the World Heritage Convention became the first international legal instrument to recognise and protect cultural landscapes. The Committee acknowledged that cultural landscapes represent the "combined works of nature and of man". In 1994, the World Heritage Committee launched the Global Strategy for a representative, balanced and credible World Heritage List. To be included on the World Heritage List, sites must be of outstanding universal value and meet at least one out of ten selection criteria. The principal core of this investigation is going to know and to analyze the urban impact, territorial effects and heritage dimension that construction of the enlightened Spanish Royal Arsenals has meant for their cities. It will be known trough the case study, the Royal Arsenal of Cartagena. At last, this research to determine which of the selection criteria of Unesco can be present in these defensive cultural landscapes