Analog VLSI-Based Modeling of the Primate Oculomotor System

One way to understand a neurobiological system is by building a simulacrum that replicates its behavior in real time using similar constraints. Analog very large-scale integrated (VLSI) electronic circuit technology provides such an enabling technology. We here describe a neuromorphic system that is part of a long-term effort to understand the primate oculomotor system. It requires both fast sensory processing and fast motor control to interact with the world. A one-dimensional hardware model of the primate eye has been built that simulates the physical dynamics of the biological system. It is driven by two different analog VLSI chips, one mimicking cortical visual processing for target selection and tracking and another modeling brain stem circuits that drive the eye muscles. Our oculomotor plant demonstrates both smooth pursuit movements, driven by a retinal velocity error signal, and saccadic eye movements, controlled by retinal position error, and can reproduce several behavioral, stimulation, lesion, and adaptation experiments performed on primates

Master of Science

thesisThis document describes an improved method of formal verification of complex analog/mixed-signal (AMS) circuits. Currently, in our LEMA tool, verification properties are encoded using labeled Petri net (LPN). These LPNs are generated manually, a tedious process that requires the user to have considerable familiarity with the tool. To eliminate this time-consuming process, our LEMA tool is extended to include a translator that converts properties written in a property specification language to LPNs. New methods are also implemented to separate the transient period from the stable output period, thus improving the generated model. Also, the current methodology generates the circuit models for the input values used during the simulation of the circuit. So, models generated for other control input values are not accurate. In this case, accuracy of the generated models is improved by using a linear abstraction method like interpolation

Master of Science

thesisVerification of analog circuits is becoming a bottle-neck for the verification of complex analog/mixed-signal (AMS) circuits. In order to assist functional verification of complex AMS system-on-chips (SoCs), there is a need to represent the transistor-level circuits in the form of abstract models. The ability to represent the analog circuits as behavioral models is necessary, but not sufficient. Though there exist languages like Verilog-AMS and VHDL-AMS for modeling AMS circuits, there is no easy method for generating these models directly from the transistor-level descriptions. This thesis presents an improved method for extracting behavioral models from the simulations of AMS circuits. This method generates labeled Petri net (LPN) models that can be used in the formal verification of circuits, and SystemVerilog models that can be used in the system-level simulations

Indirect test of M-S circuits using multiple specification band guarding

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.Peer ReviewedPostprint (author's final draft

Dynamical laser spike processing

Novel materials and devices in photonics have the potential to revolutionize optical information processing, beyond conventional binary-logic approaches. Laser systems offer a rich repertoire of useful dynamical behaviors, including the excitable dynamics also found in the time-resolved "spiking" of neurons. Spiking reconciles the expressiveness and efficiency of analog processing with the robustness and scalability of digital processing. We demonstrate that graphene-coupled laser systems offer a unified low-level spike optical processing paradigm that goes well beyond previously studied laser dynamics. We show that this platform can simultaneously exhibit logic-level restoration, cascadability and input-output isolation---fundamental challenges in optical information processing. We also implement low-level spike-processing tasks that are critical for higher level processing: temporal pattern detection and stable recurrent memory. We study these properties in the context of a fiber laser system, but the addition of graphene leads to a number of advantages which stem from its unique properties, including high absorption and fast carrier relaxation. These could lead to significant speed and efficiency improvements in unconventional laser processing devices, and ongoing research on graphene microfabrication promises compatibility with integrated laser platforms.Comment: 13 pages, 7 figure

Validation by Measurements of a IC Modeling Approach for SiP Applications

The growing importance of signal integrity (SI) analysis in integrated circuits (ICs), revealed by modern systemin-package methods, is demanding for new models for the IC sub-systems which are both accurate, efficient and extractable by simple measurement procedures. This paper presents the contribution for the establishment of an integrated IC modeling approach whose performance is assessed by direct comparison with the signals measured in laboratory of two distinct memory IC devices. Based on the identification of the main blocks of a typical IC device, the modeling approach consists of a network of system-level sub-models, some of which with already demonstrated accuracy, which simulated the IC interfacing behavior. Emphasis is given to the procedures that were developed to validate by means of laboratory measurements (and not by comparison with circuit-level simulations) the model performance, which is a novel and important aspect that should be considered in the design of IC models that are useful for SI analysi

Analysis and optimization of the hardware design of a sic mosfet based power converter with sic schottky diodes utilizing a split output topology

In recent years, the use of power electronic devices for energy conversion with semiconductors such as silicon carbide (SiC) or gallium nitride (GaN) are replacing silicon due to their high thermal conductivity, efficiency, resistance, and the possibility of smaller and thinner designs. For this reason, in order to evaluate the improvement potential of these systems, it is beneficial to realize experimental setups that emulate real operating conditions in order to verify the correct performance of these systems. In this context and based on the previous work done by Giorgio Ferrara, this thesis focuses on the analysis and identification of improvements of a SiC MOSFET-based power electronic converter with the aim of suggesting and studying different solutions that ensure a high-performance operation that allows its correct implementation in motor traction and grid-connected applications. During the thesis work, it is carried out an in-depth analysis of the voltage peaks between drain and source originated by the fast switching of the MOSFET to evaluate the use of Snubber capacitors and it is made a new hardware design of the gate driver board using isolated gate drivers to improve the dynamic behaviour in the switching transients of the SiC transistors and provide safety and robustness to the system. Finally, maintaining the original design of the converter, it implements the split output topology to evaluate possible solutions to the problems of electromagnetic interference (EMI) and the crosstalk effect that occurs with high frequency switchingNegli ultimi anni, l'uso di dispositivi elettronici di potenza per la conversione dell'energia con semiconduttori come il carburo di silicio (SiC) o il nitruro di gallio (GaN) sta sostituendo il silicio grazie alla sua elevata conducibilità termica, all'efficienza, alla resistenza e alla possibilità di realizzare disegni più piccoli e sottili. Per questo motivo, al fine di valutare il potenziale di miglioramento di questi sistemi, è utile realizzare set-up sperimentali che emulino le condizioni operative reali, in modo da poter eseguire diversi test per verificare il corretto comportamento di questi sistemi. In tale contesto e a partire dal precedente lavoro effettuato per Giorgio Ferrara, la presente tesi si concentra nell' analisi e nidentificazione di miglioramenti di un convertitore di potenza DC-AC a commutazione, al fine di proporre e studiare diverse soluzioni che garantiscano le elevate prestazioni che assicurano la sua corretta implementazione in applicazioni di trazione a motore e di connessione alla rete. Durante il lavoro di tesi, si analizza in dettaglio il fenomeno di picchi di tensione tra drain e source causato per la commutazione veloce del MOSFET e si valuta l'utilizzo di condensatori snubber; in più si realizza un nuovo disegno hardware della board di gate driver utilizzando gate driver isolati per migliorare il comportamento dinamico nei transitori di commutazione dei transistor SiC e per fornire sicurezza e robustezza al sistema. Per finire, mantenendo il disegno originale del convertitore, implementa la topologia di uscita Split Output per valutare possibili soluzioni ai problemi di interferenza elettromagnetica (EMI) e all'effetto diafonia che si produce con la commutazione ad alta frequenzaObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.5 - Augmentar la investigació científica i millorar la capacitat tecnològica dels sectors industrials de tots els països, en particular els països en desenvolupament, entre d’altres maneres fomentant la innovació i augmentant substancialment, d’aquí al 2030, el nombre de persones que treballen en el camp de la investigació i el desenvolupa­ment per cada milió d’habitants, així com la despesa en investigació i desenvolupament dels sectors públic i priva

Analysis and optimization of the hardware design of a sic mosfet based power converter with sic schottky diodes utilizing a split output topology

In recent years, the use of power electronic devices for energy conversion with semiconductors such as silicon carbide (SiC) or gallium nitride (GaN) are replacing silicon due to their high thermal conductivity, efficiency, resistance, and the possibility of smaller and thinner designs. For this reason, in order to evaluate the improvement potential of these systems, it is beneficial to realize experimental setups that emulate real operating conditions in order to verify the correct performance of these systems. In this context and based on the previous work done by Giorgio Ferrara, this thesis focuses on the analysis and identification of improvements of a SiC MOSFET-based power electronic converter with the aim of suggesting and studying different solutions that ensure a high-performance operation that allows its correct implementation in motor traction and grid-connected applications. During the thesis work, it is carried out an in-depth analysis of the voltage peaks between drain and source originated by the fast switching of the MOSFET to evaluate the use of Snubber capacitors and it is made a new hardware design of the gate driver board using isolated gate drivers to improve the dynamic behaviour in the switching transients of the SiC transistors and provide safety and robustness to the system. Finally, maintaining the original design of the converter, it implements the split output topology to evaluate possible solutions to the problems of electromagnetic interference (EMI) and the crosstalk effect that occurs with high frequency switchingNegli ultimi anni, l'uso di dispositivi elettronici di potenza per la conversione dell'energia con semiconduttori come il carburo di silicio (SiC) o il nitruro di gallio (GaN) sta sostituendo il silicio grazie alla sua elevata conducibilità termica, all'efficienza, alla resistenza e alla possibilità di realizzare disegni più piccoli e sottili. Per questo motivo, al fine di valutare il potenziale di miglioramento di questi sistemi, è utile realizzare set-up sperimentali che emulino le condizioni operative reali, in modo da poter eseguire diversi test per verificare il corretto comportamento di questi sistemi. In tale contesto e a partire dal precedente lavoro effettuato per Giorgio Ferrara, la presente tesi si concentra nell' analisi e nidentificazione di miglioramenti di un convertitore di potenza DC-AC a commutazione, al fine di proporre e studiare diverse soluzioni che garantiscano le elevate prestazioni che assicurano la sua corretta implementazione in applicazioni di trazione a motore e di connessione alla rete. Durante il lavoro di tesi, si analizza in dettaglio il fenomeno di picchi di tensione tra drain e source causato per la commutazione veloce del MOSFET e si valuta l'utilizzo di condensatori snubber; in più si realizza un nuovo disegno hardware della board di gate driver utilizzando gate driver isolati per migliorare il comportamento dinamico nei transitori di commutazione dei transistor SiC e per fornire sicurezza e robustezza al sistema. Per finire, mantenendo il disegno originale del convertitore, implementa la topologia di uscita Split Output per valutare possibili soluzioni ai problemi di interferenza elettromagnetica (EMI) e all'effetto diafonia che si produce con la commutazione ad alta frequenzaObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.5 - Augmentar la investigació científica i millorar la capacitat tecnològica dels sectors industrials de tots els països, en particular els països en desenvolupament, entre d’altres maneres fomentant la innovació i augmentant substancialment, d’aquí al 2030, el nombre de persones que treballen en el camp de la investigació i el desenvolupa­ment per cada milió d’habitants, així com la despesa en investigació i desenvolupament dels sectors públic i priva