Tecniche di progettazione tollerante alle variazioni per circuiti digitali in tecnologie nanometriche

The digital electronic market development is founded on the continuous reduction of the transistors size, to reduce area, power, cost and increase the computational performance of integrated circuits. This trend, known as technology scaling, is approaching the nanometer size. The lithographic process in the manufacturing stage is increasing its uncertainty with the scaling down of the transistors size, resulting in a larger parameter variation in future technology generations. Furthermore, the exponential relationship between the leakage current and the threshold voltage, is limiting the threshold and supply voltages scaling, increasing the power density and creating local thermal issues, such as hot spots, thermal runaway and thermal cycles. In addiction, the introduction of new materials and the smaller devices dimension are reducing transistors robustness, that combined with high temperature and frequently thermal cycles, are speeding up wear out processes. Those effects are no longer addressable only at the process level. Consequently the deep sub-micron devices will require solutions which will imply several design levels, as system and logic, and new approaches called Design For Manufacturability (DFM) and Design For Reliability. The purpose of the above approaches is to bring in the early design stages the awareness of the device reliability and manufacturability, in order to introduce logic and system able to cope with the yield and reliability loss. The ITRS roadmap suggests the following research steps to integrate the design for manufacturability and reliability in the standard CAD automated design flow: i) The implementation of new analysis algorithms able to predict the system thermal behavior with the impact to the power and speed performances. ii) High level wear out models able to predict the mean time to failure of the system (MTTF). iii) Statistical performance analysis able to predict the impact of the process variation, both random and systematic. The new analysis tools have to be developed beside new logic and system strategies to cope with the future challenges, as for instance: i) Thermal management strategy that increase the reliability and life time of the devices acting to some tunable parameter,such as supply voltage or body bias. ii) Error detection logic able to interact with compensation techniques as Adaptive Supply Voltage ASV, Adaptive Body Bias ABB and error recovering, in order to increase yield and reliability. iii) architectures that are fundamentally resistant to variability, including locally asynchronous designs, redundancy, and error correcting signal encodings (ECC). The literature already features works addressing the prediction of the MTTF, papers focusing on thermal management in the general purpose chip, and publications on statistical performance analysis. In my Phd research activity, I investigated the need for thermal management in future embedded low-power Network On Chip (NoC) devices.I developed a thermal analysis library, that has been integrated in a NoC cycle accurate simulator and in a FPGA based NoC simulator. The results have shown that an accurate layout distribution can avoid the onset of hot-spot in a NoC chip. Furthermore the application of thermal management can reduce temperature and number of thermal cycles, increasing the systemreliability. Therefore the thesis advocates the need to integrate a thermal analysis in the first design stages for embedded NoC design. Later on, I focused my research in the development of statistical process variation analysis tool that is able to address both random and systematic variations. The tool was used to analyze the impact of self-timed asynchronous logic stages in an embedded microprocessor. As results we confirmed the capability of self-timed logic to increase the manufacturability and reliability. Furthermore we used the tool to investigate the suitability of low-swing techniques in the NoC system communication under process variations. In this case We discovered the superior robustness to systematic process variation of low-swing links, which shows a good response to compensation technique as ASV and ABB. Hence low-swing is a good alternative to the standard CMOS communication for power, speed, reliability and manufacturability. In summary my work proves the advantage of integrating a statistical process variation analysis tool in the first stages of the design flow.

Ricerca ed applicazione di nuovi metodi di progettazione meccanica e di industrial design

The present dissertation relates to methodologies and technics about industrial and mechanical design. The author intends to give a complete idea about the world of design, showing the theories of Quality Function Deployment and TRIZ, of other methods just like planning, budgeting, Value Analysis and Engineering, Concurrent Engineering, Design for Assembly and Manufactoring, etc., and their applications to five concrete cases. In these cases there are also illustrated design technics as CAD, CAS, CAM; Rendering, which are ways to transform an idea into reality. The most important object of the work is, however, the birth of a new methodology, coming up from a comparison between QFD and TRIZ and their integration through other methodologies, just like Time and Cost Analysis, learned and skilled during an important experience in a very famous Italian automotive factory.

Un piano territoriale per la riduzione della concentrazione di CO2 nell'atmosfera e la produzione energetica da fonti rinnovabili per mezzo della filiera delle biomasse

Il progetto propone uno studio per verificare la fattibilita' di un piano territoriale (ideato per il bacino del Po ma di fatto estendibile a tutti i bacini fluviali) per la creazione di una filiera di colture bioenergetiche (biomasse) che, trasportate per mezzo della navigazione fluviale (uno dei mezzi di trasporto a minore emissione di CO2), alimentino una o piu' centrali a nuova tecnologia che associno alla produzione di calore (teleriscaldamento e raffreddamento) e di energia la separazione dei fumi. La CO2 catturata dalla crescita delle biomasse e recuperata dalla combustione, puo' quindi essere segregata nel sottosuolo di aree costiere subsidenti contrastando il fenomeno dell’abbassamento del suolo. Ricavando benefici in tutti i passaggi di attuazione del piano territoriale (lancio dell'agricoltura bioenergetica, rilancio della navigazione a corrente libera, avvio di una economia legata alla logistica del trasporto e dello stoccaggio delle biomasse, generazione di energia pulita, lotta alla subsidenza) il progetto, di fatto, consente di catturare ingenti quantitativi di CO2 dall'atmosfera e di segregarli nel sottosuolo, riducendo l'effetto serra. Nel corso del Dottorato e' stata sviluppata una metodologia di valutazione della sostenibilita' economica ed ambientale del progetto ad un bacino fluviale, che consta di una modulistica di raccolta dei dati di base e di una procedura informatizzata di analisi.