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

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

Design of a MEMS-based 52 MHz oscillator

Mechanical resonators are widely applied in time-keeping and frequency reference applications. Mechanical resonators are preferred over electrical resonators because of their high Q. In the $4.1 billion (2008) timing market, quartz crystals are still ubiquitous in electronic equipment. Quartz crystals show excellent performance in terms of stability (shortterm and long-term), power handling, and temperature drift. MEMS resonators are investigated as a potential alternative to the bulky quartz crystals, which cannot be integrated with IC technology. MEMS offer advantages in terms of size, cost price, and system integration. Efforts over recent years have shown that MEMS resonators are able to meet the high performance standards set by quartz. Critical success factors are high Q-factor, low temperature drift, low phase noise, and low power. This PhD thesis addresses the feasibility of scaling MEMS resonators/oscillators to frequencies above 10 MHz. The main deliverable is a 52 MHz MEMS-based oscillator. The MEMS resonators at NXP are processed on 8-inch silicon-on-insulator (SOI) wafers, with a SOI layer thickness of 1.5 µm and a buried oxide layer thickness of 1 µm. The strategic choice for thin SOI substrates has been made for two reasons. First, MEMS processing in thin silicon layers can be done with standard CMOS processing tools. The silicon dioxide layer serves as a sacrificial layer. Second, identical substrates are used for the Advanced Bipolar CMOS DMOS (ABCD) IC-processes. This class of processes can handle high voltages (ABCD2 up to 120V). The high voltage capability is suitable for the transduction of the mechanical resonator. Both MEMS and IC are processed on a similar substrate, since the strategic aim is to integrate the MEMS structure with the IC-process in the long run. Frequency scaling is investigated for both the capacitive and the piezoresistive MEMS resonator. MEMS resonators have been successfully tested from 13 MHz to over 400 MHz. This is achieved by decreasing the size of the resonator with a factor 32. We show that the thin SOI layer and the decreasing size of the resonator increase the effective impedance of the capacitive resonator at higher frequencies. For the piezoresistive resonator, we show that this readout principle is insensitive to geometrical scaling and layer thickness. Therefore, the piezoresistive readout is preferred at high frequencies. The effective impedance can be kept low, at the expense of higher power consumption. Frequency accuracy can be improved by decreasing the initial frequency spread and the temperature drift of the MEMS resonator. The main source of initial frequency spread is geometrical offset, due to the non-perfect pattern transfer from mask layout to SOI. A FEM tool has been developed in Comsol Multiphysics to obtain compensated layouts. The resonance frequency of these designs is first-order compensated for geometric offset. The FEM tool is used to obtain compensated resonators of various designs. We show empirically that the compensation by design is effective on a 52 MHz square plate design. For the compensated design, frequency spread measurements over a complete wafer show that there are other systematic sources of frequency spread. The resonance frequency of the silicon MEMS resonator drifts about –30 ppm/K. This is due to the Young’s modulus of silicon that depends on temperature. We have investigated two compensation methods. The first is passive compensation by coating the silicon resonator with a silicon dioxide skin. The Young’s modulus of silicon dioxide has a positive temperature drift. Measurements on globally oxidized structures show that the right oxide thickness reduces the linear temperature drift of the resonator to zero. A second method uses an oven-control principle. The temperature of the resonator is fixed, independent of the ambient temperature. A demo of this principle has been designed with a piezoresistive resonator in which the dc readout current through the resonator is used to control the temperature of the resonator. With both concepts, more than a factor 10 reduction in temperature drift is achieved. To demonstrate the feasibility of high-frequency oscillators, a MEMS-based 56 MHz oscillator has been designed for which a piezoresistive dogbone resonator is used. The amplifier has been designed in the ABCD2 IC-process. The MEMS oscillator consumes 6.1 mW and exhibits a phase noise of –102 dBc/Hz at 1 kHz offset from the carrier and a floor of –113 dBc/Hz. This demonstrates feasibility of the piezoresistive MEMS oscillator for lowpower, low-noise applications. Summarizing, this PhD thesis work as part of the MEMSXO project at NXP demonstrates a MEMS oscillator concept based on the piezoresistive resonator in thin SOI. It shows that by compensated designs for geometric offset and oven-control to reduce temperature drift, a frequency accuracy can be achieved that can compete with the performance of crystal oscillators. In a benchmark with MEMS competitors the concept shows the lowest phase noise, making it the most suited concept for wireless applications

ENABLING IOT AUTHENTICATION, PRIVACY AND SECURITY VIA BLOCKCHAIN

Although low-power and Internet-connected gadgets and sensors are increasingly integrated into our lives, the optimal design of these systems remains an issue. In particular, authentication, privacy, security, and performance are critical success factors. Furthermore, with emerging research areas such as autonomous cars, advanced manufacturing, smart cities, and building, usage of the Internet of Things (IoT) devices is expected to skyrocket. A single compromised node can be turned into a malicious one that brings down whole systems or causes disasters in safety-critical applications. This dissertation addresses the critical problems of (i) device management, (ii) data management, and (iii) service management in IoT systems. In particular, we propose an integrated platform solution for IoT device authentication, data privacy, and service security via blockchain-based smart contracts. We ensure IoT device authentication by blockchain-based IC traceability system, from its fabrication to its end-of-life, allowing both the supplier and a potential customer to verify an IC’s provenance. Results show that our proposed consortium blockchain framework implementation in Hyperledger Fabric for IC traceability achieves a throughput of 35 transactions per second (tps). To corroborate the blockchain information, we authenticate the IC securely and uniquely with an embedded Physically Unclonable Function (PUF). For reliable Weak PUF-based authentication, our proposed accelerated aging technique reduces the cumulative burn-in cost by ∼ 56%. We also propose a blockchain-based solution to integrate the privacy of data generated from the IoT devices by giving users control of their privacy. The smart contract controlled trust-base ensures that the users have private access to their IoT devices and data. We then propose a remote configuration of IC features via smart contracts, where an IC can be programmed repeatedly and securely. This programmability will enable users to upgrade IC features or rent upgraded IC features for a fixed period after users have purchased the IC. We tailor the hardware to meet the blockchain performance. Our on-die hardware module design enforces the hardware configuration’s secure execution and uses only 2,844 slices in the Xilinx Zedboard Zynq Evaluation board. The blockchain framework facilitates decentralized IoT, where interacting devices are empowered to execute digital contracts autonomously

NASA Space Engineering Research Center Symposium on VLSI Design

The NASA Space Engineering Research Center (SERC) is proud to offer, at its second symposium on VLSI design, presentations by an outstanding set of individuals from national laboratories and the electronics industry. These featured speakers share insights into next generation advances that will serve as a basis for future VLSI design. Questions of reliability in the space environment along with new directions in CAD and design are addressed by the featured speakers

NASA Tech Briefs, July 1991

Topics include: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

MEMS Accelerometers

Micro-electro-mechanical system (MEMS) devices are widely used for inertia, pressure, and ultrasound sensing applications. Research on integrated MEMS technology has undergone extensive development driven by the requirements of a compact footprint, low cost, and increased functionality. Accelerometers are among the most widely used sensors implemented in MEMS technology. MEMS accelerometers are showing a growing presence in almost all industries ranging from automotive to medical. A traditional MEMS accelerometer employs a proof mass suspended to springs, which displaces in response to an external acceleration. A single proof mass can be used for one- or multi-axis sensing. A variety of transduction mechanisms have been used to detect the displacement. They include capacitive, piezoelectric, thermal, tunneling, and optical mechanisms. Capacitive accelerometers are widely used due to their DC measurement interface, thermal stability, reliability, and low cost. However, they are sensitive to electromagnetic field interferences and have poor performance for high-end applications (e.g., precise attitude control for the satellite). Over the past three decades, steady progress has been made in the area of optical accelerometers for high-performance and high-sensitivity applications but several challenges are still to be tackled by researchers and engineers to fully realize opto-mechanical accelerometers, such as chip-scale integration, scaling, low bandwidth, etc

NASA Tech Briefs, January 1992

Topics include: New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Fabrication; Mathematics and Information Sciences; Life Sciences