Francesco D'Ascoli

Wafer-level vacuum packaged resonant micro-scanning mirrors for compact laser projection displays

Scanning laser projection using resonant actuated MEMS scanning mirrors is expected to overcome the current limitation of small display size of mobile devices like cell phones, digital cameras and PDAs. Recent progress in the development of compact modulated RGB laser sources enables to set up very small laser projection systems that become attractive not only for consumer products but also for automotive applications like head-up and dash-board displays. Within the last years continuous progress was made in increasing MEMS scanner performance. However, only little is reported on how mass-produceability of these devices and stable functionality even under harsh environmental conditions can be guaranteed. Automotive application requires stable MEMS scanner operation over a wide temperature range from -40° to +85°Celsius. Therefore, hermetic packaging of electrostatically actuated MEMS scanning mirrors becomes essential to protect the sensitive device against particle contamination and condensing moisture. This paper reports on design, fabrication and test of a resonant actuated two-dimensional micro scanning mirror that is hermetically sealed on wafer level. With resonant frequencies of 30kHz and 1kHz, an achievable Theta-D-product of 13mm.deg and low dynamic deformation <20nm RMS it targets Lissajous projection with SVGA-resolution. Inevitable reflexes at the vacuum package surface can be seperated from the projection field by permanent inclination of the micromirror.

Intelligent sensor interface for automotive applications

This paper presents a new platform for interfacing a generic sensor for automotive applications, called ISIF (Intelligent Sensor InterFace). Such platform consists in a wide set of optimized high performance analog, digital and software IPs for various kind of sensors. These IPs can be extracted for fast prototyping accurate and reliable interface circuits for the target automotive application. Therefore the main advantage of this platform-based design approach is to give the possibility to bring up complex and ad-hoc sensor conditioning systems, reducing development risks, design effort, power consumption, costs and time-to-market.

Hot wire anemometric MEMS sensor for water flow monitoring

This paper presents an application based on a hot wire anemometric sensor in MEMS technology in the field of water flow monitoring. New generations of MEMS sensors feature remarkable savings in area, costs and power respect to conventional discrete devices, but as drawback, they require complex electronic interfaces for signal conditioning to achieve high performances and a high reliability. This anemometric sensor implementation has been developed with ISIF, a platform SoC, aiming to fast prototype a wide range of sensors thanks to its high configurable resources. The presented system achieves good performances with respect to commercial devices, featuring resolution of plusmn0.35% up to plusmn1.76% with repeatability roughly plusmn1% respect to the full scale (0-250 cm/s). Furthermore the proposed system, thanks to the compact size of the sensor, its robustness and its low costs can represent a solution for diffusive monitoring in water distribution networks.

A mixed-signal embedded platform for automotive sensor conditioning

A mixed-signal embedded system called Intelligent Sensor InterFace (ISIF) suited to fast identify, trim, and verify an architecture to interface a given sensor is presented. This system has been developed according to a platform-based design approach, a methodology that has proved to be efficient for building complex mixed-signal embedded systems with short time-to-market. Such platform consists in a wide set of optimized high-performance analog, digital, and software intellectual property (IP) modules for various kinds of sensors. These IPs can be easily defined for fast prototyping of the interface circuit for the given sensor. Final ASIC implementation for the given sensor conditioning can be easily derived with reduced risk and short development time. Some case examples are presented to demonstrate the effectiveness and flexibility of this system.

An Integrated Flow from pre-Silicon Simulation to post-Silicon Verification

This paper presents an integrated flow to bridge the existing gap from pre-silicon simulation to post-silicon verification environments. This flow features automatic reproduction in lab of the test-bench used in simulation and sharing of data between design and test environments. A design for testability (DFT) approach has been also used to increase the controllability and observability of the system. This integrated flow has been successfully used to validate a mixed-signal IC developed by SensorDynamicsAG for sensor conditioning leading to time and cost reduction and to an increased reliability and quality of the overall test phase (simulation and verification)

Design of an integrated scanning micromirror driver in BCD technology

The paper presents the design and characterization of a smart IC driver for MEMS scanning micromirrors. The driver integrates in 0.18 μm 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.

Design of a high voltage fully differential driver for a double axis scanning micromirror

The design of a high voltage fully differential driver in a 0.18 µm Bipolar-CMOS-DMOS (BCD) technology for the actuation of a double axis scanning micromirror is presented. The proposed circuit has a driving voltage capability up to 25 V and a low Total Harmonic Distortion in order to prevent the excitation of unwanted micromirrors higher resonating modes. This design features a low voltage input stage and a programmable output common mode voltage. After a description of the circuit, results of simulations performed with an equivalent electrical model of the micromirror are presented.

Low-g accelerometer fast prototyping for automotive applications

This paper presents an application of the ISIF chip (intelligent sensor interface), for conditioning a dual-axis low-g accelerometer in MEMS technology. MEMS are nowadays the standard in automotive applications (and not only), as they feature a drastic reduction in cost, area and power, while they require a more complex electronic interface with respect to traditional discrete devices. ISIF is a platform on chip implementation, aiming to fast prototype a wide range of automotive sensors thanks to its high configuration resources, achieved both by full analog / digital IPs trimming options and by flexible routing structures. This accelerometer implementation exploits a relevant part of ISIF hardware resources, but also requires signal processing add-ins (software emulation of digital DSP blocks) for the closed loop conditioning architecture and for performance improvement (for example temperature drift compensation). In spite the short prototyping time, the resulting system achieves good performances with respect to commercial devices, featuring a 0.9 mg/radicHz noise density with 1024 LSB/g sensitivity on the digital output over a +/- 2g FS, and an offset drift over 100degC range within 30 mg, with 2% of FS sensitivity drift. Miniboards have been developed as product prototypes, consisting of a small PCB with ISIF and accelerometer dies bonded together, firmware embedded in EEPROM and communication transceivers

A programmable and low-EMI integrated half-bridge driver in BCD technology

This paper presents the design and the laboratory results of an integrated half-bridge driver for power electronic systems in a 0.35 mum bipolar CMOS DMOS (BCD) technology. The proposed solution is designed for frequency applications up to several hundred of KHz and it has a driving current capability up to 50 mA. This work features a design configuration and a digital control to reduce electromagnetic interference (EMI). Moreover it includes short circuit protection, programmability of voltage references and a digital control circuitry implementing mechanism to prevent dangerous failures of the driver. After a deep description of the circuit we show the laboratory results of the half-bridge driver used to drive a 20 KHz antenna.