10 research outputs found

    A cost-effective 10-bit D/A converter for digital-input MOEMS micromirror actuation

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    The design of a 10-bit resistor-string digital-to-analog converter (DAC) for MOEMS micromirror interfacing is addressed in this paper. The proposed DAC, realized in a 0.18-μm BCD technology, features a folded resistor-string stage with a switch matrix and address decoders plus an output voltage buffer stage. The proposed DAC and buffer circuitry are key elements of an innovative scanning micromirror actuator, characterized by direct digital input, full differential driving, and linear response. With respect to the the state-of-the-art resistor-string converters in similar technologies, the proposed DAC has comparable nonlinearity (INL, DNL) performances while it has the advantage of a smaller area occupation, 0.17 mm2, including output buffer, and relatively low-power consumption, 200 μW at 500 kSPS and few μW in idle mode

    Design of integrated mixed-signal IPs for automotive applications

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    An ever-increasing range of sophisticated and leading-edge electronic technologies emerging into the automotive field makes this one of the most dynamic but even complicated manufacturing sector in the world. Car companies are convinced that electronic is the key to meet different and often divergent requirements such as high-safety vehicles, comfort, infotainment, gas emission reduction, power saving, low cost technologies and short time to market. For these reasons the expectations on the electronic automotive systems are very high since it seems to be the major factor of innovation technology and differentiation in a more and more competitive market field. The hardness of this market scenario has a direct impact on the complexity of electronic systems. Many features on modern medium-segment cars are based on high performance Electronic Control Units dealing with up to 2500 signals. As a consequence the number of sensing and actuating elements hidden into the body or the chassis of a car is growing continuously. Moreover as many hydraulic and mechanical actuators are replaced by power consuming electronic components and new entertainment features are provided to meet customer’s requests, power saving becomes an issue even in the automotive field. The PhD research activity has been focused on the design of integrated electronic systems for the automotive fields. The new requirements of the automotive market together with the necessity to reduce time to market imply a complete review of the electronic systems design flows. For these reasons the PhD activities have been always leaded following a platform based design approach in order to give a proper answer to the aforementioned requirements and to give a more efficient alternative to the actual design approaches. Chapter 1 of this thesis explains in much more details the automotive market requirements focusing on the characteristics of each particular segment and presenting the main actual and future automotive applications. A particular attention is given to the electronic automotive challenges and design issues implied by this scenario that has motivated the overall PhD activities. Chapter 2 starts with the presentation of the actual state of the art of the methodologies used in the electronic automotive field and continues with the description of the proposed platform called Intelligent Sensor InterFace (ISIF). ISIF is a platform targeted to interface automotive sensors and is composed by a high number of highly programmable software and hardware IPs. The platform has been integrated in a 0.35 um Bipolar CMOS DMOS (BCD) technology supplied by STMicroelectronics. Some case studies regarding fast prototyping possibilities with ISIF are presented: a magneto-resistive position sensor and two capacitive inertial sensors (in collaboration with SensorDynamics AG), a gyro and a low-g YZ accelerometer. Chapter 3 describes the extension of the ISIF application space to high power automotive systems and to laser based video projection systems: High power automotive systems are gaining importance during the last years since many mechanical and hydraulic features are completely transferred to electronic systems. In this thesis the design and test of a programmable MOS half bridge driver featuring low ElectroMagnetic Interferences (EMIs) and targeted to electric motor and antenna driving is presented. Laser based video projection systems are expected to find a wide utilization for the realization of new generation automotive head up displays thanks to the recent advance of Micro-Opto-Electromechanical Systems (MOEMS) and visible laser sources. The thesis shows in details the technical characteristics of this topic and describes the design and simulation results of a scanning micromirrors high voltage driver in a 0.18 um BCD technology supplied by STMicroelectronics

    Mixed-signal integrated circuits design and validation for automotive electronics applications

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    Automotive electronics is a fast growing market. In a field primarily dominated by mechanical or hydraulic systems, over the past few decades there has been exponential growth in the number of electronic components incorporated into automobiles. Partly thanks to the advance in high voltage smart power processes in nowadays cars is possible to integrate both power/high voltage electronics and analog/digital signal processing circuitry thus allowing to replace a lot of mechanical systems with electro-mechanical or fully electronic ones. High level modeling of complex electronic systems is gaining importance relatively to design space exploration, enabling shorter design and verification cycles, allowing reduced time-to-market. A high level model of a resistor string DAC to evaluate nonlinearities has been developed in MATLAB environment. As a test case for the model, a 10 bit resistive DAC in 0.18um is designed and the results were compared with the traditional transistor level approach. Then we face the analysis and design of a fundamental block: the bandgap voltage reference. Automotive requirements are tough, so the design of the voltage reference includes a pre-regulation part of the battery voltage that allows to enhance overall performances. Moreover an analog integrated driver for an automotive application whose architecture exploits today’s trends of analog-digital integration allowing a greater range of flexibility allowing high configurability and fast prototipization is presented. We covered also the mixed-signal verification approach. In fact, as complexity increases and mixed-signal systems become more and more pervasive, test and verification often tend to be the bottleneck in terms of time effort. A complete flow for mixed-signal verification using VHDL-AMS modeling and Python scripting is presented as an alternative to complex transistor level simulations. Finally conclusions are drawn

    Platform-based design, test and fast verification flow for mixed-signal systems on chip

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    This research is providing methodologies to enhance the design phase from architectural space exploration and system study to verification of the whole mixed-signal system. At the beginning of the work, some innovative digital IPs have been designed to develop efficient signal conditioning for sensor systems on-chip that has been included in commercial products. After this phase, the main focus has been addressed to the creation of a re-usable and versatile test of the device after the tape-out which is close to become one of the major cost factor for ICs companies, strongly linking it to model’s test-benches to avoid re-design phases and multi-environment scenarios, producing a very effective approach to a single, fast and reliable multi-level verification environment. All these works generated different publications in scientific literature. The compound scenario concerning the development of sensor systems is presented in Chapter 1, together with an overview of the related market with a particular focus on the latest MEMS and MOEMS technology devices, and their applications in various segments. Chapter 2 introduces the state of the art for sensor interfaces: the generic sensor interface concept (based on sharing the same electronics among similar applications achieving cost saving at the expense of area and performance loss) versus the Platform Based Design methodology, which overcomes the drawbacks of the classic solution by keeping the generality at the highest design layers and customizing the platform for a target sensor achieving optimized performances. An evolution of Platform Based Design achieved by implementation into silicon of the ISIF (Intelligent Sensor InterFace) platform is therefore presented. ISIF is a highly configurable mixed-signal chip which allows designers to perform an effective design space exploration and to evaluate directly on silicon the system performances avoiding the critical and time consuming analysis required by standard platform based approach. In chapter 3 we describe the design of a smart sensor interface for conditioning next generation MOEMS. The adoption of a new, high performance and high integrated technology allow us to integrate not only a versatile platform but also a powerful ARM processor and various IPs providing the possibility to use the platform not only as a conditioning platform but also as a processing unit for the application. In this chapter a description of the various blocks is given, with a particular emphasis on the IP developed in order to grant the highest grade of flexibility with the minimum area occupation. The architectural space evaluation and the application prototyping with ISIF has enabled an effective, rapid and low risk development of a new high performance platform achieving a flexible sensor system for MEMS and MOEMS monitoring and conditioning. The platform has been design to cover very challenging test-benches, like a laser-based projector device. In this way the platform will not only be able to effectively handle the sensor but also all the system that can be built around it, reducing the needed for further electronics and resulting in an efficient test bench for the algorithm developed to drive the system. The high costs in ASIC development are mainly related to re-design phases because of missing complete top-level tests. Analog and digital parts design flows are separately verified. Starting from these considerations, in the last chapter a complete test environment for complex mixed-signal chips is presented. A semi-automatic VHDL-AMS flow to provide totally matching top-level is described and then, an evolution for fast self-checking test development for both model and real chip verification is proposed. By the introduction of a Python interface, the designer can easily perform interactive tests to cover all the features verification (e.g. calibration and trimming) into the design phase and check them all with the same environment on the real chip after the tape-out. This strategy has been tested on a consumer 3D-gyro for consumer application, in collaboration with SensorDynamics AG

    FLEXIBLE LOW-COST HW/SW ARCHITECTURES FOR TEST, CALIBRATION AND CONDITIONING OF MEMS SENSOR SYSTEMS

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    During the last years smart sensors based on Micro-Electro-Mechanical systems (MEMS) are widely spreading over various fields as automotive, biomedical, optical and consumer, and nowadays they represent the outstanding state of the art. The reasons of their diffusion is related to the capability to measure physical and chemical information using miniaturized components. The developing of this kind of architectures, due to the heterogeneities of their components, requires a very complex design flow, due to the utilization of both mechanical parts typical of the MEMS sensor and electronic components for the interfacing and the conditioning. In these kind of systems testing activities gain a considerable importance, and they concern various phases of the life-cycle of a MEMS based system. Indeed, since the design phase of the sensor, the validation of the design by the extraction of characteristic parameters is important, because they are necessary to design the sensor interface circuit. Moreover, this kind of architecture requires techniques for the calibration and the evaluation of the whole system in addition to the traditional methods for the testing of the control circuitry. The first part of this research work addresses the testing optimization by the developing of different hardware/software architecture for the different testing stages of the developing flow of a MEMS based system. A flexible and low-cost platform for the characterization and the prototyping of MEMS sensors has been developed in order to provide an environment that allows also to support the design of the sensor interface. To reduce the reengineering time requested during the verification testing a universal client-server architecture has been designed to provide a unique framework to test different kind of devices, using different development environment and programming languages. Because the use of ATE during the engineering phase of the calibration algorithm is expensive in terms of ATE’s occupation time, since it requires the interruption of the production process, a flexible and easily adaptable low-cost hardware/software architecture for the calibration and the evaluation of the performance has been developed in order to allow the developing of the calibration algorithm in a user-friendly environment that permits also to realize a small and medium volume production. The second part of the research work deals with a topic that is becoming ever more important in the field of applications for MEMS sensors, and concerns the capability to combine information extracted from different typologies of sensors (typically accelerometers, gyroscopes and magnetometers) to obtain more complex information. In this context two different algorithm for the sensor fusion has been analyzed and developed: the first one is a fully software algorithm that has been used as a means to estimate how much the errors in MEMS sensor data affect the estimation of the parameter computed using a sensor fusion algorithm; the second one, instead, is a sensor fusion algorithm based on a simplified Kalman filter. Starting from this algorithm, a bit-true model in Mathworks Simulink(TM) has been created as a system study for the implementation of the algorithm on chip

    MEMS Technology for Biomedical Imaging Applications

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    Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

    Supraspinal activity patterns underpinning locomotor diversity in larval zebrafish

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    How do supraspinal circuits produce the diversity of locomotor outputs needed for an animal’s survival? To answer this question, I study the reticulospinal (RS) system of larval zebrafish, as these cells provide the main source of descending motor control. I combine two-photon calcium imaging of RS neurons with high-speed behavioural tracking to study RS activity across a range of kinematically distinct swim types. Examination of reticulospinal recruitment across different swim types has revealed unique, but partially overlapping activity patterns, suggesting that some cells encode kinematics common to multiple swim types, while others encode kinematics which are characteristic of a specific swim type. By developing regression-based encoding models which describe a cell’s activity using low-level tail kinematics, we identify “kinematic modules”. These modules contain cells with similar kinematic encoding and thus represent the core combinations of kinematic features encoded by RS activity. I find that laser ablation of cells within a module produce specific kinematic deficits without affecting shared elements of locomotion. This data suggest a circuit architecture where kinematic modules can be differentially combined to produce locomotor diversity through the context-specific recruitment of particular groups of RS neurons. I also describe a novel preparation for the imaging of fluorescent activity indicators in larval zebrafish using an acousto-optic lens microscope. This methodology allows for rapid 3D point scanning of the entire reticulospinal complex during visual stimulus presentation and behavioural tracking. The improved temporal resolution and sampling across the whole population provides an opportunity to examine the relative timing of activity between reticulospinal neurons

    Design of an integrated scanning micromirror driver in BCD technology

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    The paper presents the design and characterization of a smart IC driver for MEMS scanning micromirrors. The driver integrates in 0.18 mu m BCD technology the cascade of the following circuits: resistor-string DAC circuitry for direct interface to a host digital processing unit, a voltage buffer between the DAC and the High-Voltage (HV) stage, and a fully-differential HV amplifier with programmable output common mode. A couple of the designed DACs permits to generate, starting from digital samples, low-voltage analog stimuli. This signal amplified up to 25 V by the HV stage provides the electrostatical actuation of the micromirror. When compared to state-of-the-art the driver offers an integrated solution with good dynamic performances
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