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Advanced CMOS IC Design Techniques for Optimizing the Baseband Analog Front-End of Mobile Phones
No full textSummary
Nowadays, the desire to always be connectable by a communication device is larger than ever, thus growing the needs for the development of circuits that will make the dream of this Global Village a reality. Mobility, while remaining reachable at all the time, is possible with the use of wireless communications that have the common characteristic of having a limited power source in the battery. This pushes to improve the circuit techniques to increase the portable electronic device autonomy. A higher autonomy makes a product more usable, lighter (because a smaller battery is necessary), and much more appealing to the consumer. Systems with a higher functionality, higher capacity and a slick design are only possible if power consumption is reduced to a minimum. Furthermore, new products are developed on a regular basis. As a consequence, system integrators and everyone working in such a competitive environment see their time-to-market as a small window of opportunity. All design steps until the product reaches the shop shelves have to be optimized. Usually, the first steps in the engineering development require a large percentage of this time, which has to be minimized to keep costs low.
The presented work has been developed in cooperation between the R&D department of ST-Ericsson Switzerland and the University of Rome “Sapienza”. It covers the modeling, analysis, design, optimization and IC characterization of two different analog and mixed-signal sections of today’s baseband front-end of mobile phones: the audio subsystem and the power management unit (PMU). The final goal is to optimize the two sub-sections in terms of efficiency, performance and area reduction, pushing the overall integration and costs to a leading edge level.
In the first part, concerning the audio subsystem, the following topics have been addressed:
• The design of a class-AB/D audio power amplifier in standard 65nm CMOS technology for direct battery hook-up. Circuit techniques are used to overcome the voltage limitations of standard MOS transistors for operation at voltage levels of 2.5V-4.8V. Both amplifiers can drive more than 650mW into an 8 load with distortion levels of 1% and 5% for class-D and class-AB, respectively, all from a 3.6V power supply. The achieved power-supply-rejection ratios (PSRR) are 72dB and 84dB, respectively. The stereo implementation of both amplifiers together is smaller than 0.5mm2.
• The design of a fully integrated solution for a single speaker mobile application. It makes use of a capacitor-free low-dropout regulator (LDO) which shares the pass device with the output audio power stage, allowing high quality performances for both hands-free and receiver modes and high power for hands-free. The system is capable of delivering 1W in hands-free operation, and 80mW in receive with 118dB of PSRR and 0.06% of THD. The whole design has been implemented using TSMC 45nm CMOS technology.
• A novel topology for a micro-machined acoustic speaker suitable for cellular phones. The membrane is composed of two materials, both of them with different functions: a silicon moving part acting as a rigid piston and a polymer annulus acting only as suspension. The high ratio between Young moduli and masses of membrane and suspension leads to a simpler design of the mass-spring-damper system. This new topology can be obtained thanks to a new micromachining technology that leads to a higher adhesion between polymer and silicon. Simulations presenting the main micro-loudspeaker parameters (e.g. SPL, frequency response) are presented in detail as well as in the principal technological steps.
In the second part, for the PMU section, several topics are presented as well:
• A fully independent ground referenced power management unit (GRPMU) for headset audio, made up of two linear regulators and a regulated charge pump providing symmetrical power supply for the headset audio amplifier. It aims to reduce the cost of the external components as well as to improve the integration level. It has been implemented in standard CMOS 65nm technology. Details on the architecture and the final measurement on silicon are presented.
As improvement for the GRPMU system, an innovative inverting charge pump on a series-parallel architecture is presented as well. Implemented in 40nm CMOS technology, all the details of the architecture and the final measurement on silicon are shown, highlighting great performance in terms of efficiency and THD when applied as negative power supply for high quality earphone audio amplifiers.
• An ultra-low power, integrated coulomb counter gas gauging system which is able to consume only 40µA during sleep mode with good accuracy; it is implemented in 45nm CMOS technology.
• A 1.2A DCDC boost converter with integrated NMOS switch for delivering higher audio power, compatible with low voltage battery standard, showing about 80% efficiency, implemented in 45nm CMOS technology.
All the circuit design work has been designed, simulated and measured in the R&D department of ST-Ericsson Switzerland, using edge CMOS technology and packaged in ST-Microelectronics in Crolles (France). In the case of the microspeaker design, the sample has been manufactured in the Electronic Engineering Department of the University of Rome “Sapienza” with the help of Prof. Balucani.
Research overview and contributions
For each application, complexity and performance must be carefully weighed against power consumption. Even though the desire is to integrate as much as possible, one must remember that this might not always lead to a more power efficient circuit. Each one of the available technological options, when properly combined, offer not only the desired increased battery autonomy but also a lower cost. The research work that is now completed has contributed, amongst others, the following results:
• An high quality, fully integrated and totally flexible audio solution in terms of a 700mWrms class AB/D amplifier together with a ground referenced power management unit which are today integrated in millions of phones in the market;
• A fully integrated solution for low end market phones which require the usage of a single speaker solution;
• A novel inverting charge pump for future and more efficient ground referenced audio solutions;
• A high power DCDC boost converter with integrated switch for providing more than 1Wrms audio power for the hands-free melodies.
The analysis, simulation, optimization and measurement of audio and power management circuits in CMOS have been discussed in this thesis. Several steps towards extreme integration have been shown, highlighting what can still be further investigated. It was shown that it is possible to achieve high power, high voltage design in leading edge CMOS technologies without any change in the process flow and several high voltage design tricks have been presented.
Possibilities for future work
Future research can continue, either incrementally from the point where the presented study has left off or by pursuing one of the following suggestions. High performances can be obtained in a relatively inexpensive technology like CMOS, but the main advantages arise from the possibility of integrating a full system on a chip. Nevertheless, the fact should be stressed that the most difficult thing in any design like the ones presented in this work is measuring. Without measurement results this type of work is unfinished, even though this is sometimes a disregarded issue. Advancements can come both from integration, where the final product design is eased, and by increasing the performance of a single block. Several issues can be addressed and different research paths can be followed, of which the following seem interesting to dedicate more time to.
• Single speaker application has not been implemented yet on silicon and this can be the first thing to be tried for use in the future, following the guidelines showed in this work and then having the chance of measuring concrete results;
• First important steps towards a possible integration of a micro-speaker as MEMS device has been presented. This work can continue further with a CMOS technology allowing MEMS device integration, which today is not available within ST-Ericsson;
• The DCDC boost converter can undergo a further integration, through diode on silicon for example.ST-Ericsso
Spatial memory and plasticity: molecular mechanisms in the hippocampus and the ventral striatum
No full textFormation of long-term memories (LTM) is accomplished through structural changes of neurons leading to a rearrangement of the neural networks requiring gene expression and protein synthesis. Evidence for local mRNAs and translational machineries at dendrites has suggested that post-transcriptional regulatory mechanisms at this level might also be crucial in the stabilization of LTM. In particular microRNAs (miRs), small noncoding molecules, have been demonstrated a role in post-transcriptional gene regulation.
The hippocampus and the ventral striatum (VS) are considered as key structures in the stabilization of spatial memories. In order to shade light on molecular processes underlying such stabilization during my PhD we performed a large scale screening of miR and mRNAs expression in these two brain regions after spatial learning. CD1 mice were trained with a massed procedure in the spatial version of the water maze. 1 hour after training, the hippocampus and the VS were dissected and RNA extracted. To study the spatial learning component, we compared miR expression profiles of mice submitted to the spatial procedure with those of mice exposed to the same context but without require the application of a spatial strategy.
The results of microarray analysis showed modification in miR and mRNA expression levels, both up and down-regulation, in both brain structures after learning. To verify a possible causal relationship between miRs and experience dependent plasticity we overexpressed, learning downregulated miR, before training in water maze. Mimic but not scramble injected mice showed impaired ability to locate the correct quadrant on the probe test.
Our results demonstrate for the first time in vivo, the importance of miRs regulation in long-term memory processes. Interestingly, spatial learning induced profile of both miR and mRNA expression varied between the two structures. Thus suggesting that different molecular mechanisms might underlie learning induced plasticity in different brain areas.Ministero dell'Istruzione, dell'Università e della Ricerca, Sapienza Università di Roma, Agenzia Spaziale Italiana
Performance Models of Concurrency Control Protocols for Transaction Processing Systems
No full textTransaction processing plays a key role in a lot of IT infrastructures. It is widely used in a variety of contexts, spanning from database management systems to concurrent programming tools. Transaction processing systems leverage on concurrency control protocols, which allow them to concurrently process transactions preserving essential properties, as isolation and atomicity.
Performance is a critical aspect of transaction processing systems, and it is unavoidably affected by the concurrency control. For this reason, methods and techniques to assess and predict the performance of concurrency control protocols are of interest for many IT players, including application designers, developers and system administrators. The analysis and the proper understanding of the impact on the system performance of these protocols require quantitative approaches. Analytical modeling is a practical approach for building cost-effective computer system performance models, enabling us to quantitatively describe the complex dynamics characterizing these systems. In this dissertation we present analytical performance models of concurrency control protocols. We deal with both traditional transaction processing systems, such as database management systems, and emerging ones, as transactional memories. The analysis focuses on widely used protocols, providing detailed performance models and validation studies. In addition, we propose new modeling approaches, which also broaden the scope of our study towards a more realistic, application-oriented, performance analysis
Physical-Chemical study for the characterization and for the traceability of archaeological finds in the Rome area
No full textThe present research concerns a comparative study between the chemical and mineralogical composition of the sixteen century potteries found inside the Castle of Pope Giulio II in Ostia Antica (Rome) and clay samples taken from the quarries of roman territory historically validated.
The purpose of this research has been to provide scientific support to archaeologists who are carrying out studies to establish if the ancient ceramics collected had been made in roman territory or imported from the major famous pottery factories of central-northen Italy. The study of geographical traceability of everyday objects such as potteries would be important to trace the production part of Rome in a era in which wars and invasions had created great social unrest. Specifically, have been carried out experimental
X-ray diffraction analysis of minerals, chemical composition analysis by La-ICP-MS(Laser Ablaction-Inductively Coupled Plasma-Mass) techniques and optical and electronic SEM (Scanning Electron Microscope ) microscopy images have been studied.
All of the data obteined was processed with different statistical methods, such as the linear correlation between the chemical composition of clay and ceramics and the multivariate analysis (PCA) in order to formulate hypothesis concerning the production geographic area of archeological findsTesi di dottorato di ricercaMinistero per i Beni e le Attività Cultural
Analisi e confronto del LEC (levelised energy cost) per impianti solari termodinamici, idroelettrici e a carbone in caso di incertezza e irreversibilità
No full textL'italiano delle traduzioni di Shakespeare e Defoe tra Otto e Novecento
No full textIl lavoro si propone di studiare l'italiano delle traduzioni di Shakespeare e Defoe tra Ottocento e Novecento. L'intento della ricerca è duplice: da un lato vedere come la lingua delle traduzioni è cambiata attraverso i due secoli presi in considerazione e dall'altro analizzare quale rapporto intercorre tra la lingua di queste traduzioni e l'italiano della letteratura coeva
Strategie di memoria e di metamemoria: processi motivazionali e di autoefficacia negli adulti e anziani studenti
No full textLa ricerca indaga la componente metacognitiva e motivazionale alla base dell’autoregolazione dell’apprendimento, nell’ambito dell’educazione agli adulti e agli anziani (studenti non tradizionali). Obiettivi della ricerca sono stati: verificare le performance mnestiche, motivazionali e di autoefficacia, possedute dagli studenti non tradizionali, confrontandole con le performance di giovani studenti universitari (studenti tradizionali) e di adulti e anziani che non hanno intrapreso nessun corso formativo in età avanzata (non studenti).
Attraverso la costruzione di uno strumento che misurasse le strategie di memoria e di metamemoria e inserito all’interno di una batteria di test, destinati alla misurazione della motivazione intrinseca, dell’autoefficacia accademica ed emotiva e della tendenza alla desiderabilità sociale, sono state misurate le variabili metacognitive e motivazionali che regolavano il processo di apprendimento in età avanzata
Role of redox-activated DNA damage response in the regulation of drug-induced NKG2D and DNAM-1 ligand expression on human senescent multiple myeloma cells
No full textIncreasing evidence indicate that stimulation of the host immune response represents a promising therapeutic approach against cancer. Multiple Myeloma (MM) is a debilitating malignancy in which abnormal plasma cells (PCs) accumulate in the bone marrow, and a number of evidence showed that MM cells are potential targets of Natural Killer (NK) cell killing. The expression of NK cell activating DNAM-1 and NKG2D ligands on multiple myeloma cells has been described, and although the regulation of NKG2D ligands is not completely understood, increasing evidence demonstrate that cellular stress and induction of DNA damage response can up-regulate their expression. Little information is available about the mechanisms controlling DNAM-1 ligand regulation.
In this study, we show that myeloma cells treated with low doses of therapeutic agents commonly used in the management of patients with MM, such as doxorubicin, melphalan, and bortezomib, up-regulate DNAM-1 and NKG2D ligands. Accordingly, therapeutic drug treatment of MM cells increases NK-cell degranulation, being the NKG2D and DNAM-1 receptors the major triggering molecules. Similar data were also obtained using ex vivo primary PCs derived from MM patients. We demonstrated that drug-induced NKG2D and DNAM-1 ligand up-regulation was triggered by the DNA damage response pathway and, in particular, ATM/ATR and Chk1/2 have a key role. By contrast, p53 phosphorylation is induced by chemotherapeutic treatments but is not involved in ligand up-regulation. We showed that low doses of genotoxic agents lead MM cells to enter in a premature senescence, characterized by a G2M phase-arrested cell cycle, and that NKG2D and DNAM-1 ligand up-regulation occurs preferentially on senescent cells. Moreover, our experiments demonstrated a role for the Reactive Oxygen Species (ROS) in drug-induced DNA damage response activation and subsequent ligand up-regulation and senescent phenotype.
Altogether, our findings have identified a common pathway that can trigger the up-regulation of different NK cell-activating ligands and suggest that NK cells represent an immunosurveillance mechanism toward cells undergoing stress-induced senescent programs
hMENA splicing program in tumor progression: functional role of isoforms in pancreatic cancer cell adhesion and migration
No full texthMENA, a member of the Ena/VASP proteins involved in the cytoskeletal regulation during cell motility and adhesion, is up-regulated in invasive tumor cells and plays a crucial role in metastatic progression. We show that hMENA alternative splicing is related to EMT process and this is in line with recent data demonstrating that hMENA belongs to a cluster of genes whose alternative splicing is related to EMT.
Our group has previously characterized two hMENA isoforms, one 88-kDa isoform defined as “classic” and one splice variants, named hMENA11a (90 kDa). Here we report a novel splice variant of human MENA, named hMENAΔv6 (80 kDa). hMENA11a characterizes epithelial cancer cell lines expressing E-Cadherin, whereas hMENAΔv6 is expressed in breast and cervix tumor cell lines displaying the phenotypic features of EMT with migratory behaviour. The analysis of pancreatic cell lines indicates that hMENA11a is expressed in the normal human pancreatic ductal epithelial cell line (HPDE) besides epithelial pancreatic tumor cell lines (CFPAC, T3M4, and PACA44), whereas hMENAΔv6 is expressed in PANC1 cells that lack hMENA11a and express Vimentin.
We observed that the Ser157 of VASP is phosphorylated either in normal or pancreatic cancer cell lines with an epithelial phenotype and expressing hMENA11a, whereas the hMENA11a negative/hMENAΔv6 positive PANC1 cell line did not show appreciate level of P-Ser157 VASP. By gain and loss of function, we demonstrate that hMENA11a espression is able to induce VASP phosphorylation at Ser157 and that hMENA11a transduction in PANC1 cells resembles the pattern of VASP phosphorylation observed in HPDE cells. We analyzed the effects of hMENA11a mutants in PANC1 cells by the substitution of the two putative serine sites of phosphorylation present in 11a peptide to alanine. Biochemical results evidenced that only wild type hMENA11a transduction is able to induce VASP phosphorylation at Ser157, whereas the two mutants did not affect VASP phosphorylation.
Epithelial cells express one or more of the Ena/VASP proteins, and these in turn localize to the leading edges of lamellipodia, the tips of filopodia, focal adhesions, cell–cell junctions. Our results demonstrate that P-Ser157 VASP interacts with hMENA11a and both proteins localize within focal adhesions in HPDE cells. PKA activation increases the pool of P-Ser157 VASP and hMENA11a at the cell periphery, whereas both proteins disappear from the cell periphery when PKA is inhibited. hMENA11a transduction in PANC1 resembles P-Ser157 VASP and hMENA11a localization at the cell periphery.
At functional level, we analyze whether the hMENA splicing program differently affect the ability of PANC1 cells to adhere and invade ECM. hMENA11a or ESRP1 transduction increases P-Ser157 level in cells plated on collagen type I or fibronectin, together with an increase of cell-matrix adhesion. Furthermore, hMENA11a or ESRP1 transduction determines a reduction of cancer cell invasion in a BM-coated Boyden chamber.
Differently from the breast model, where hMENA is not expressed in normal epithelium but overexpressed following transformation and tumor progression, hMENA and hMENA11a are co-expressed in normal pancreas whereas primary tumors lack the expression of the epithelial hMENA11a isoform, suggesting that hMENA splicing may be altered in pancreatic tumor progression. Altogheter, our results demonstrate that hMENA splicing is a critical step in cancer and the lost of epithelial hMENA11a isoform strongly contributes to the aggressivness of this incurable neoplasia
