Modular architecture for ultra low power switched-capacitor DC-DC converters

This work presents a novel architecture for a step down Switched Capacitor Converter for Ultra Low Power applications such as implantable devices,Wireless Sensor Nodes, portable devices, etc. The objective is to supply energy to digital circuits such as micro-controllers using the Dynamic Voltage Scaling technique that allows to optimize the trade-off between performance and consumption. Other important applications of this type of converters are the newest technologies where the transistors are not able to tolerate the voltage provided by the different types of batteries. The more conversion ratios the converter has the better to apply the Dynamic Voltage Scaling technique it is. This is because different performance levels in digital circuits need different supply voltages to minimize the power consumption while achieving the needed performance. In the literature there are some works in the area, all of them with the particularity of having a rigid architecture based on particular configurations for each conversion level. This makes this type of converters not suitable for adding easily more conversion ratios. The architecture proposed in this work has the particularity of being modular and being able to easily add new conversion ratios if necessary. Each module (named Basic Capacitor Cell) is composed by a capacitor and a fourswitch configuration. The number of modules used in the converter defines the number of conversion ratios. The Basic Capacitor Cells are connected in a ring configuration that can be opened in each node to connect the supply voltage. Then the load is connected to one of the intermediate nodes. Given the modularity of the converter a general numerical model was developed. This model allows to predict the performance of the converter for an arbitrary number of conversion ratios. As the model uses some data extracted from electrical simulation and some parameters of the technology, it can easily be used for any technology. The model is suitable to make design space exploration and avoid long electrical simulations times. A four-conversion-ratios converter was developed and electrically simulated in the technology On Semi 0,5μm with an input voltage of 2,8V . The peak efficiency achieved is 78%. This performance is similar to the one achieved by existing works in the literature. The logic was implemented but not the control loop. A novel technique to improve the losses in parasitic capacitances was proposed and simulated. This technique makes a redistribution of the charge between the parasitic capacitances that need to lose energy and those that need to gain energy. Since parasitic capacitances losses are dominant in this architecture.Este trabajo presenta una arquitectura novedosa para la implementacion de convertidores DC-DC de condensadores conmutados de Ultra Bajo Consumo para aplicaciones como dispositivos implantables, redes de sensores inalambricos, dispositivos portatiles, entre otros. El objetivo es suministrar energia a circuitos digitales tales como microcontroladores usando la tecnica de escalado dinamico de voltaje que permite manejar el compromiso entre la performance y el consumo del circuito. Otra importante aplicacion de este tipo de convertidores es para las nuevas tecnologias donde los transistores no soportan el voltaje entregado por los distintos tipos de pilas. Cuantos mas niveles de conversion tenga el convertidor mejor se puede aplicar la tecnica de escalado dinamico de voltaje. Esto es porque diferentes niveles de performance de un circuito digital necesitan diferentes voltajes de alimentacion para minimizar la potencia disipada alcanzando la performance necesaria. Existen algunos trabajos en el area, todos ellos tienen la particularidad de utilizar arquitecturas rigidas basadas en configuraciones particulares para cada nivel de conversion. Esto hace que este tipo de convertidores no sea apropiado para aumentar facilmente la cantidad de niveles de conversion. La arquitectura propuesta en este trabajo tiene la particularidad de ser modular y permite facilmente agregar mas niveles de conversion si fuera necesario, a la vez que simplifica el dise?ada modulo esta compuesto por un condensador y una configuracion de cuatro switches. El numero de modulos usado en el convertidor define el numero de niveles de conversion. Los modulos son conectados en forma de anillo el cual puede ser abierto en cualquiera de los nodos con el fin de conectar la fuente de alimentacion. Luego la carga es conectada a uno de los nodos intermedios del anillo segun el nivel de conversion deseado. Dada la modularidad del convertidor un modelo numerico general fue desarrollado. Este modelo permite tener una prediccion de la performance del convertidor para un numero arbitrario de niveles de conversion. Dado que el modelo utiliza datos extraidos de simulaciones electricas y algunos parametros de la tecnologia, facilmente puede ser usado para cualquier tecnologia. El modelo es apropiado para realizar exploraciones del espacio de dise? evitar los prolongados tiempos de las simulaciones electricas. Un convertidor de cuatro niveles de conversion fue desarrollado y simulado a nivel electrico en la tecnologia On Semi 0,5µm con un voltaje de alimentacion de 2,8V . El pico de eficiencia alcanzado es de 78%. Esta performance es similar a la alcanzada por los trabajos existentes en la literatura. Para este convertidor la logica fue implementado, pero no el lazo de control que fija la tension de salida. Una novedosa tecnica para disminuir las perdidas en las capacidades parasitas fue propuesta y simulada. Dicha tecnica realiza una redistribucion de la carga entre las capacidades parasitas que necesitan perder energia y aquellas que necesitan ganarla. Dado que las perdidas en las capacidades parasitas son dominantes en esta arquitectura, una mejora significativa fue lograda en la eficiencia a partir de la aplicacion de esta tecnica

Enhanced ICMR amplifier for high CMRR biopotential recordings

PostprintThis paper presents an integrated biopotential preamplifier architecture targeting applications that simultaneously require high common-mode rejection ratio (CMRR), low noise, high input common-mode range (ICMR), and current-efficiency (low Noise Efficiency Factor or NEF). A biopotential preamplifier, which performs well in line with the state-of-the-art of the field while providing enhanced ICMR and CMRR performance, was fabricated in a 0.5 μm CMOS process. Results from measurements show that the gain is 47 dB, the bandwidth ranges from 1 Hz to 7.7 kHz, the equivalent input noise is 1.8 μV rms , the CMRR is 100.5 dB, the ICMR is 1.7 V and the NEF is 3.2

Relaxing the maximum dc input amplitude vs. consumption trade-off in differential-input band-pass biquad filters.

This paper shows that an important part of the power consumption of a biquad band‐pass filter is associated with the feedback loop that fixes the high‐pass frequency and blocks the direct current (dc) input signals. The dc input amplitude that can be blocked is related to the maximum output current that one of the transconductors can provide, hence impacting on the required consumption through this effect. Then, a technique that efficiently blocks the dc input signal and fixes the high‐pass frequency is introduced and analyzed in depth. Moreover, an architecture for ultra‐low‐power differential‐input biquads is fully presented. The proposed architecture enables lowering the power consumption or blocking higher levels of dc input without jeopardizing the power consumption. Results show that the proposed architecture, compared with a traditional one, presents a 30% reduction in power consumption and more than doubles the dc input that can be blocked

Reciclado de carga y circuitos para mejora de la eficiencia en conversores DC/DC integrados de ultra baja potencia

El presente trabajo profundiza en el estudio de conversores DC/DC de capacitores conmutados totalmente integrados para aplicaciones de ultra bajo consumo como ser: dispositivos implantables, redes de sensores inalámbricos, dispositivos portátiles, etc. El objetivo de este tipo de sistemas es el de suministrar energía al circuito correspondiente pero con una tensión diferente a la de la batería utilizada. Básicamente hay dos razones para suministrar una tensión diferente a la de la fuente principal. Por un lado, en los circuitos digitales existe un compromiso entre performance (velocidad de procesamiento) y consumo, que en general se puede manejar mediante la técnica de escalado dinámico de voltaje y frecuencia ("Dynamic Voltage and Frequency Scaling"), esta técnica básicamente disminuye la tensión de alimentación y la frecuencia del sistema cuando la exigencia de procesamiento es baja y los sube cuando es alta. De esta forma, en muchas aplicaciones se puede ahorrar una cantidad significativa de energía. Por otro lado, el escalado de las nuevas tecnologías ha alcanzado un punto donde los transistores básicos no soportan la tensión de las baterías que se consiguen en el mercado. Para ambos casos, tener un conversor DC/DC que sea capaz de manejar todo el rango (o al menos una buena parte) entre tierra y la tensión de alimentación es esencial. En esta tesis, se contribuye a la mejora de la e ciencia de este tipo de conversores con varias técnicas que permiten reciclar parte de la carga asociada a capacidades parásitas, y por técnicas de diseño de circuitos de bloques auxiliares. La idea de reciclar la carga de las capacidades parásitas ha sido explorada en la literatura, sin embargo todos los antecedentes están limitados a arquitecturas particulares del conversor DC/DC. En este trabajo se proponen técnicas generales para reciclar la carga de capacidades parásitas asociadas a las placas de los capacitores principales (capacidades parásitas de "top/bottom plate") y capacidad de gate independientemente de la arquitectura del conversor. Dichas técnicas son independientes de la arquitectura del conversor

Flores Celestes (1807): O livro secreto de José da Silva Lisboa, o visconde de Cairú

The present article investigates the origins of a mysterious little book intitled Flores celestes colhidas entre os espinhos da sagrada coroa da augusta, veneravel e soberana cabeça do divino e immortal rei dos seculos Jesus Christo, of authorship of the enigmatic bahiense poet Jose Cortez Sol Posto, also known as Cigano da Bahia. The inquiry demonstrates that, under the layer of merciful poetries, the confessions of one of the most representative personages of the History of Brazil in century XIX are hidden.En este artículo se investiga el origen de un misterioso y pequeño libro titulado Flores celestes colhidas entre os espinhos da sagrada coroa da augusta, veneravel e soberana cabeça do divino e immortal rei dos seculos Jesus Christo, escrito por el enigmático poeta bahiense José Cortez Sol Posto, también conocido como Cigano da Bahia. La investigación muestra que, bajo el pretexto de la poesía piadosa, se esconden las confesiones de uno de los personajes más importantes de la historia de Brasil en el siglo XIX. [pt] O presente artigo investiga as origens de um livrinho misterioso intitulado Flores celestes colhidas entre os espinhos da sagrada coroa da augusta, veneravel e soberana cabeça do divino e immortal rei dos seculos Jesus Christo, de autoria do enigmático poeta bahiense José Cortez Sol Posto, também conhecido como Cigano da Bahia. A investigação demonstra que, sob a capa de poesias piedosas, escondem-se as confissões de um dos mais representativos personagens da História do Brasil no século XIX

What is the frequency of floor of the mouth lesions? A descritive study of 4,016 cases

The aim of this study was to investigate the frequency of oral lesions in the floor of the mouth from representative oral pathology centres in Latin America. This study was conducted on biopsies obtained from January of 1978 to December of 2018 at nine Latin America oral and maxillofacial pathology centres. Gender, age and histopathological diagnosis were evaluated. Data were analysed using descriptive methods. Chi-square test was used for pairwise comparisons. From 114,893 samples, 4,016 lesions (3.49%) occurred in the floor of the mouth. Brazil showed 3,777 cases (94%), Mexico 182 cases (4.5%) and Argentina 57 cases (1.4%). Benign lesions represented 65.1% (2,617 cases), followed by 34.9% (1,404 cases) of malignant disorders. Lesions of epithelial origin were more frequent (1,964 cases; 48.9%), followed by salivary glands (1,245 cases; 31%) and soft tissue lesions (475 cases; 11.7%). The most common histological subtypes were oral squamous cell carcinoma (1,347 cases; 33.5%), ranula (724 cases; 18%), oral leukoplakia (476 cases; 11.8%) and inflammatory fibrous hyperplasia (239 cases; 5.9%). The lesion affected males in 2,129 cases and females in 1,897 cases. In the current study, lesions in the floor of the mouth represented 3.49% of biopsies submitted to oral pathology services and oral squamous cell carcinoma, ranula and leukoplakia were the most common lesions

Surface indicators are correlated with soil multifunctionality in global drylands

1. Multiple ecosystem functions need to be considered simultaneously to manage and protect the several ecosystem services that are essential to people and their environments. Despite this, cost effective, tangible, relatively simple and globally relevant methodologies to monitor in situ soil multifunctionality, that is, the provision of multiple ecosystem functions by soils, have not been tested at the global scale. 2. We combined correlation analysis and structural equation modelling to explore whether we could find easily measured, field‐based indicators of soil multifunctionality (measured using functions linked to the cycling and storage of soil carbon, nitrogen and phosphorus). To do this, we gathered soil data from 120 dryland ecosystems from five continents. 3. Two soil surface attributes measured in situ (litter incorporation and surface aggregate stability) were the most strongly associated with soil multifunctionality, even after accounting for geographic location and other drivers such as climate, woody cover, soil pH and soil electric conductivity. The positive relationships between surface stability and litter incorporation on soil multifunctionality were greater beneath the canopy of perennial vegetation than in adjacent, open areas devoid of vascular plants. The positive associations between surface aggregate stability and soil functions increased with increasing mean annual temperature. 4. Synthesis and applications. Our findings demonstrate that a reduced suite of easily measured in situ soil surface attributes can be used as potential indicators of soil multifunctionality in drylands world‐wide. These attributes, which relate to plant litter (origin, incorporation, cover), and surface stability, are relatively cheap and easy to assess with minimal training, allowing operators to sample many sites across widely varying climatic areas and soil types. The correlations of these variables are comparable to the influence of climate or soil, and would allow cost‐effective monitoring of soil multifunctionality under changing land‐use and environmental conditions. This would provide important information for evaluating the ecological impacts of land degradation, desertification and climate change in drylands world‐wide.This work was funded by the European Research Council ERC Grant agreement 242658 (BIOCOM). CYTED funded networking activities (EPES, Acción 407AC0323). D.J.E. acknowledges support from the Australian Research Council (DP150104199) and F.T.M. support from the European Research Council (BIODESERT project, ERC Grant agreement no 647038), from the Spanish Ministerio de Economía y Competitividad (BIOMOD project, ref. CGL2013-44661-R) and from a Humboldt Research Award from the Alexander von Humboldt Foundation. M.D.-B. was supported by REA grant agreement no 702057 from the Marie Sklodowska-Curie Actions of the Horizon 2020 Framework Programme H2020-MSCA-IF-2016), J.R.G. acknowledges support from CONICYT/FONDECYT no 1160026

Enfermedades crónicas

Adherencia al tratamiento farmacológico y relación con el control metabólico en pacientes con DM2Aluminio en pacientes con terapia de reemplazo renal crónico con hemodiálisis en Bogotá, ColombiaAmputación de extremidades inferiores: ¿están aumentando las tasas?Consumo de edulcorantes artificiales en jóvenes universitariosCómo crecen niños normales de 2 años que son sobrepeso a los 7 añosDiagnóstico con enfoque territorial de salud cardiovascular en la Región MetropolitanaEfecto a corto plazo de una intervención con ejercicio físico, en niños con sobrepesoEfectos de la cirugía bariátrica en pacientes con síndrome metabólico e IMC < 35 KG/M2Encuesta mundial de tabaquismo en estudiantes de profesiones de saludEnfermedades crónicas no transmisibles: Consecuencias sociales-sanitarias de comunidades rurales en ChileEpidemiología de las muertes hospitalarias por patologías relacionadas a muerte encefálica, Chile 2003-2007Estado nutricional y conductas alimentarias en adolescentes de 4º medio de la Región de CoquimboEstudio de calidad de vida en una muestra del plan piloto para hepatitis CEvaluación del proceso asistencial y de resultados de salud del GES de diabetes mellitus 2Factores de riesgo cardiovascular en población universitaria de la Facsal, universidad de TarapacáImplicancias psicosociales en la génesis, evolución y tratamiento de pacientes con hipertensión arterial esencialInfarto agudo al miocardio (IAM): Realidad en el Hospital de Puerto Natales, 2009-2010Introducción de nuevas TIC y mejoría de la asistencia a un programa de saludNiños obesos atendidos en el Cesfam de Puerto Natales y su entorno familiarPerfil de la mortalidad por cáncer de cuello uterino en Río de JaneiroPerfil del paciente primo-consultante del Programa de Salud Cardiovascular, Consultorio Cordillera Andina, Los AndesPrevalencia de automedicación en mujeres beneficiarias del Hospital Comunitario de Til-TiPrevalencia de caries en población preescolar y su relación con malnutrición por excesoPrevalencia de retinopatía diabética en comunas dependientes del Servicio de Salud Metropolitano Occidente (SSMOC)Problemas de adherencia farmacológica antihipertensiva en población mapuche: Un estudio cualitativoRol biológico de los antioxidantes innatos en pacientes portadores de VIH/SidaSobrepeso en empleados de un restaurante de una universidad pública del estado de São Paul

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding