A Low-Power Sigma-Delta Modulator for Healthcare and Medical Diagnostic Applications

This paper presents a switched-capacitor Sigma-Delta modulator designed in 90-nm CMOS technology, operating at 1.2-V supply voltage. The modulator targets healthcare and medical diagnostic applications where the readout of small-bandwidth signals is required. The design of the proposed A/D converter was optimized to achieve the minimum power consumption and area. A remarkable performance improvement is obtained through the integration of a low-noise amplifier with modified Miller compensation and rail-to-rail output stage. The manuscript also presents a set of design equations, from the small-signal analysis of the amplifier, for an easy design of the modulator in different technology nodes. The Sigma-Delta converter achieves a measured 96-dB dynamic range, over a 250-Hz signal bandwidth, with an oversampling ratio of 500. The power consumption is 30 μW, with a silicon area of 0.39 mm²

Frontotemporal dementia and its subtypes: a genome-wide association study

SummaryBackground Frontotemporal dementia (FTD) is a complex disorder characterised by a broad range of clinical manifestations, differential pathological signatures, and genetic variability. Mutations in three genes—MAPT, GRN, and C9orf72—have been associated with FTD. We sought to identify novel genetic risk loci associated with the disorder. Methods We did a two-stage genome-wide association study on clinical FTD, analysing samples from 3526 patients with {FTD} and 9402 healthy controls. To reduce genetic heterogeneity, all participants were of European ancestry. In the discovery phase (samples from 2154 patients with {FTD} and 4308 controls), we did separate association analyses for each {FTD} subtype (behavioural variant FTD, semantic dementia, progressive non-fluent aphasia, and {FTD} overlapping with motor neuron disease FTD-MND), followed by a meta-analysis of the entire dataset. We carried forward replication of the novel suggestive loci in an independent sample series (samples from 1372 patients and 5094 controls) and then did joint phase and brain expression and methylation quantitative trait loci analyses for the associated (p<5 × 10−8) single-nucleotide polymorphisms. Findings We identified novel associations exceeding the genome-wide significance threshold (p<5 × 10−8). Combined (joint) analyses of discovery and replication phases showed genome-wide significant association at 6p21.3, \{HLA\} locus (immune system), for rs9268877 (p=1·05 × 10−8; odds ratio=1·204 95% \{CI\} 1·11–1·30), rs9268856 (p=5·51 × 10−9; 0·809 0·76–0·86) and rs1980493 (p value=1·57 × 10−8, 0·775 0·69–0·86) in the entire cohort. We also identified a potential novel locus at 11q14, encompassing RAB38/CTSC (the transcripts of which are related to lysosomal biology), for the behavioural \{FTD\} subtype for which joint analyses showed suggestive association for rs302668 (p=2·44 × 10−7; 0·814 0·71–0·92). Analysis of expression and methylation quantitative trait loci data suggested that these loci might affect expression and methylation in cis. Interpretation Our findings suggest that immune system processes (link to 6p21.3) and possibly lysosomal and autophagy pathways (link to 11q14) are potentially involved in FTD. Our findings need to be replicated to better define the association of the newly identified loci with disease and to shed light on the pathomechanisms contributing to FTD. Funding The National Institute of Neurological Disorders and Stroke and National Institute on Aging, the Wellcome/MRC Centre on Parkinson's disease, Alzheimer's Research UK, and Texas Tech University Health Sciences Center

Mendelian randomization implies no direct causal association between leukocyte telomere length and amyotrophic lateral sclerosis

Funder: QingLan Research Project of Jiangsu for Outstanding Young TeachersFunder: Project funded by Postdoctoral Science Foundation of Xuzhou Medical UniversityFunder: Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) for Xuzhou Medical UniversityAbstract: We employed Mendelian randomization (MR) to evaluate the causal relationship between leukocyte telomere length (LTL) and amyotrophic lateral sclerosis (ALS) with summary statistics from genome-wide association studies (n = ~ 38,000 for LTL and ~ 81,000 for ALS in the European population; n = ~ 23,000 for LTL and ~ 4,100 for ALS in the Asian population). We further evaluated mediation roles of lipids in the pathway from LTL to ALS. The odds ratio per standard deviation decrease of LTL on ALS was 1.10 (95% CI 0.93–1.31, p = 0.274) in the European population and 0.75 (95% CI 0.53–1.07, p = 0.116) in the Asian population. This null association was also detected between LTL and frontotemporal dementia in the European population. However, we found that an indirect effect of LTL on ALS might be mediated by low density lipoprotein (LDL) or total cholesterol (TC) in the European population. These results were robust against extensive sensitivity analyses. Overall, our MR study did not support the direct causal association between LTL and the ALS risk in neither population, but provided suggestive evidence for the mediation role of LDL or TC on the influence of LTL and ALS in the European population

Un approccio sistematico all'analisi e al design di macchine elettriche per applicazioni di trazione automobilistica

Negli ultimi decenni, il processo di elettrificazione ha interessato diversi aspetti e attività delle moderne società industrializzate. In questo contesto, l'elettrificazione dei trasporti mostra ancora un ritardo significativo. Ciò è dovuto principalmente alle prestazioni altamente competitive del petrolio come fonte di energia sia sotto il profilo tecnico sia economico. Tuttavia, le considerazioni in merito all'inquinamento dell'aria unitamente a politiche di autosufficienza energetica hanno recentemente aumentato l'interesse dell'industria automobilistica verso i powertrain ibridi ed elettrici. Inoltre, in pochi anni, i powertrain elettrici hanno raggiunto le prestazioni di quelli a combustione interna e, grazie a particolari caratteristiche (quali ad esempio il sovraccarico e gli alti livelli di efficienza), hanno persino superato i risultati dei powertrains convenzionali. Il presente lavoro di tesi si concentra sulle macchine elettriche usate per la propulsione e il freno dei nuovi autoveicoli, con una particolare attenzione alla geometria di rotore, alle configurazioni degli avvolgmenti e ai più importanti trade-off relativi al design della macchina elettrica. Anche le possibilità di controllo sull'intero intervallo di velocità sono state considerate accuratamente. In più, un nuovo modello magnetico ricorsivo è stato sviluppato per eseguire ottimizzazioni multi-obiettivo dei parametri di rotore e un'inedita geometria di tipo spoke-type viene proposta per ridurre il volume del magnete permanente nella macchina. Questa tesi è organizzata nel seguente modo: l'introduzione fornisce le informazioni di contesto generale in materia di elettrificazione dell'automobile, il capitolo 1 si occupa dei requisiti specifici di un motore per trazione dimostrando che i motori a magneti permanenti interni sono quelli che meglio soddisfano tali vincoli, nel capitolo 2 un'approfondita analisi di due macchine prese in considerazione come casi di studio viene svolta per mezzo sia di un'approccio analitico sia di simulazioni a elementi finiti, quindi nel capitolo 3 si esegue un'analisi critica delle principali opzioni di progetto della macchina e infine, nel capitolo 4, le linee-guida risultanti vengono applicate al design di un nuovo motore prototipo destinato alle corse di formula studentesca (SAE). Il progetto copre non soltanto i tipici aspetti elettromagnetici del motore ma anche le proprietà termiche e meccaniche della macchina.In the last decades, the electrification process has involved several aspects and activities of modern industrialized societies. In this context, the electrification of the transportation sector still exhibits a significant delay. This is mainly due to the rather competitive oil performances as an energy source from both a technical and economic point of view. However, air pollution considerations as well as energy self-sufficiency policies have recently raised the industrial interest for automotive hybrid and electric powertrains. Moreover, in just a few years, the electrical powertrains have reached the Internal Combustion Engine performances and, thanks to their particular features (such as the overload and the very high efficiency levels), they even outperformed most of the conventional powertrains. This work focuses on the electrical machines used for the new car propulsion and braking, with special regard to the rotor geometry, winding configurations and all the most important trade-offs related to the machine design. The control capabilities over the whole speed range have also been considered carefully. In addition, a new recursive magnetic model has been developed to perform multi-objective rotor parameters optimization and a novel spoke-type geometry is proposed to reduce the machine permanent magnet volume. This thesis is organized in the following way: the introduction gives the general background information about the car electrification topic, the chapter 1 deals with the specific requirements for a traction motor showing that the Interior Permanent Magnet is the motor type which best meets those constraints, in the chapter 2 a deep analysis is carried out on two case study machines by means of both analytic approach and Finite Elements simulations, then chapter 3 performs a critical analysis of the machine main design options and finally, in chapter 4, the resultant guidelines are applied to the design of a new motor prototype for Student Formula races. The design covers not only the typical electric and magnetic aspects of the motor but also the thermal and mechanical properties of the machine

A systematic approach to the analysis and design of electrical machines for automotive traction applications

Negli ultimi decenni, il processo di elettrificazione ha interessato diversi aspetti e attività delle moderne società industrializzate. In questo contesto, l'elettrificazione dei trasporti mostra ancora un ritardo significativo. Ciò è dovuto principalmente alle prestazioni altamente competitive del petrolio come fonte di energia sia sotto il profilo tecnico sia economico. Tuttavia, le considerazioni in merito all'inquinamento dell'aria unitamente a politiche di autosufficienza energetica hanno recentemente aumentato l'interesse dell'industria automobilistica verso i powertrain ibridi ed elettrici. Inoltre, in pochi anni, i powertrain elettrici hanno raggiunto le prestazioni di quelli a combustione interna e, grazie a particolari caratteristiche (quali ad esempio il sovraccarico e gli alti livelli di efficienza), hanno persino superato i risultati dei powertrains convenzionali. Il presente lavoro di tesi si concentra sulle macchine elettriche usate per la propulsione e il freno dei nuovi autoveicoli, con una particolare attenzione alla geometria di rotore, alle configurazioni degli avvolgmenti e ai più importanti trade-off relativi al design della macchina elettrica. Anche le possibilità di controllo sull'intero intervallo di velocità sono state considerate accuratamente. In più, un nuovo modello magnetico ricorsivo è stato sviluppato per eseguire ottimizzazioni multi-obiettivo dei parametri di rotore e un'inedita geometria di tipo spoke-type viene proposta per ridurre il volume del magnete permanente nella macchina. Questa tesi è organizzata nel seguente modo: l'introduzione fornisce le informazioni di contesto generale in materia di elettrificazione dell'automobile, il capitolo 1 si occupa dei requisiti specifici di un motore per trazione dimostrando che i motori a magneti permanenti interni sono quelli che meglio soddisfano tali vincoli, nel capitolo 2 un'approfondita analisi di due macchine prese in considerazione come casi di studio viene svolta per mezzo sia di un'approccio analitico sia di simulazioni a elementi finiti, quindi nel capitolo 3 si esegue un'analisi critica delle principali opzioni di progetto della macchina e infine, nel capitolo 4, le linee-guida risultanti vengono applicate al design di un nuovo motore prototipo destinato alle corse di formula studentesca (SAE). Il progetto copre non soltanto i tipici aspetti elettromagnetici del motore ma anche le proprietà termiche e meccaniche della macchina. In the last decades, the electrification process has involved several aspects and activities of modern industrialized societies. In this context, the electrification of the transportation sector still exhibits a significant delay. This is mainly due to the rather competitive oil performances as an energy source from both a technical and economic point of view. However, air pollution considerations as well as energy self-sufficiency policies have recently raised the industrial interest for automotive hybrid and electric powertrains. Moreover, in just a few years, the electrical powertrains have reached the Internal Combustion Engine performances and, thanks to their particular features (such as the overload and the very high efficiency levels), they even outperformed most of the conventional powertrains. This work focuses on the electrical machines used for the new car propulsion and braking, with special regard to the rotor geometry, winding configurations and all the most important trade-offs related to the machine design. The control capabilities over the whole speed range have also been considered carefully. In addition, a new recursive magnetic model has been developed to perform multi-objective rotor parameters optimization and a novel spoke-type geometry is proposed to reduce the machine permanent magnet volume. This thesis is organized in the following way: the introduction gives the general background information about the car electrification topic, the chapter 1 deals with the specific requirements for a traction motor showing that the Interior Permanent Magnet is the motor type which best meets those constraints, in the chapter 2 a deep analysis is carried out on two case study machines by means of both analytic approach and Finite Elements simulations, then chapter 3 performs a critical analysis of the machine main design options and finally, in chapter 4, the resultant guidelines are applied to the design of a new motor prototype for Student Formula races. The design covers not only the typical electric and magnetic aspects of the motor but also the thermal and mechanical properties of the machine

Accurate Modeling of Ultra Low-Power Σ∆ Modulator

This paper presents a behavioural model suitable for the simulation of low-power Sigma-Delta Modulators. Second- order effects affecting the settling behaviour of the switched- capacitor integrator was included, leading to improved accuracy. Due to the oversampling mode of the converter, transistor-level simulations are extremely time consuming. Accurate behavioural models are thus mandatory in the first design phase of the modulator, in particular when the involved analog blocks must be optimized for minimum power consumption at some converter resolution

Stability and performance analysis of a voltage controlled resistor circuit for wide band-gap device gate drivers

Wide band-gap devices are making inroads in the power converters scenario, and specific circuits to drive these components are actively under development. The purpose of this paper is to analyze, from the stability and dynamic performance point of view, a Voltage Controlled Power Resistor (VCPR), that can be used to control the gate resistance of the device driver with values over a continuous range. Parametric analysis, SPICE simulations and experimental outcomes are presented, in order to determine circuit characteristics. Results show that the proposed topology is stable under a wide range of electric parameters, and suggest that the circuit bandwidth can be tuned in order to benefit from the VCPR in a wide band-gap device gate driver

Wavelet-based prognostic-oriented temperature sensing with sigma-delta ADCs in power applications

Thermal stress is one of many possible failure causes of power electronics systems; thermal cycles are known to produce mechanical fatigue on power electronic devices, thus leading to their failure in time. Temperature swing can be somehow controlled, if some decrease in efficiency can be tolerated by the power system, changing gate driver parameters to heat up the device in low load conditions. This is known as Active Thermal Control (ATC). To implement ATC, the temperature information of devices is needed. Since this sensing is carried out near power conductors, switched at high frequency, strong disturbances will affect the reading. This paper proposes a new signal-conditioning scheme based on discrete wavelet transform (DWT) and compares it to some established filtering techniques to assess which is most suitable for the application. Hints about insulation of measuring equipment will be given, too. Moreover, the possibility offered by the algorithms to store long-Time temperature information (through compression of incoming data) will be described, as large-span observation can help prognostic algorithms in forecasting the remaining useful life of the power apparatus

Stability and Performance Analysis of a Voltage Controlled Resistor Circuit for Wide Band-gap Device Gate Drivers

Wide band-gap devices are making inroads in the power converters scenario, and specific circuits to drive these components are actively under development. The purpose of this paper is to analyze, from the stability and dynamic performance point of view, a Voltage Controlled Power Resistor (VCPR), that can be used to control the gate resistance of the device driver with values over a continuous range. Parametric analysis, SPICE simulations and experimental outcomes are presented, in order to determine circuit characteristics. Results show that the proposed topology is stable under a wide range of electric parameters, and suggest that the circuit bandwidth can be tuned in order to benefit from the VCPR in a wide band-gap device gate driver