76 research outputs found
Use of CCD to Detect Terrestrial Cosmic Rays at Ground Level: Altitude vs. Underground Experiments, Modeling and Numerical Monte Carlo Simulation
International audienceIn this work, we used a commercial charge-coupled device (CCD) camera to detect and monitor terrestrial cosmic rays at ground level. Multi-site characterization has been performed at sea level (Marseille), underground (Modane Underground Laboratory) and at mountain altitude (Aiguille du Midi-Chamonix Mont-Blanc at +3,780 m of altitude) to separate the atmospheric and alpha particle emitter's contributions in the CCD response. An additional experiment at avionics altitude during a long-haul flight has been also conducted. Experiment results demonstrate the importance of the alpha contamination in the CCD response at ground level and its sensitivity to charged particles. Experimental data as a function of CCD orientation also suggests an anisotropy of the particle flux for which the device is sensitive. A complete computational modeling of the CCD imager has been conducted, based on a simplified 3D CCD architecture deduced from a reverse engineering study using electron microscopy and physico-chemical analysis. Monte Carlo simulations evidence the major contribution of low energy (below a few MeV) protons and muons in the CCD response. Comparison between experiments and simulation shows a good agreement at ground level, fully validated at avionics altitudes with a much higher particle flux and a different particle cocktail composition
Analysis and Design of Resilient VLSI Circuits
The reliable operation of Integrated Circuits (ICs) has become increasingly difficult to
achieve in the deep sub-micron (DSM) era. With continuously decreasing device feature
sizes, combined with lower supply voltages and higher operating frequencies, the noise
immunity of VLSI circuits is decreasing alarmingly. Thus, VLSI circuits are becoming
more vulnerable to noise effects such as crosstalk, power supply variations and radiation-induced
soft errors. Among these noise sources, soft errors (or error caused by radiation
particle strikes) have become an increasingly troublesome issue for memory arrays as well
as combinational logic circuits. Also, in the DSM era, process variations are increasing
at an alarming rate, making it more difficult to design reliable VLSI circuits. Hence, it
is important to efficiently design robust VLSI circuits that are resilient to radiation particle
strikes and process variations. The work presented in this dissertation presents several
analysis and design techniques with the goal of realizing VLSI circuits which are tolerant
to radiation particle strikes and process variations.
This dissertation consists of two parts. The first part proposes four analysis and two
design approaches to address radiation particle strikes. The analysis techniques for the
radiation particle strikes include: an approach to analytically determine the pulse width
and the pulse shape of a radiation induced voltage glitch in combinational circuits, a technique
to model the dynamic stability of SRAMs, and a 3D device-level analysis of the
radiation tolerance of voltage scaled circuits. Experimental results demonstrate that the proposed techniques for analyzing radiation particle strikes in combinational circuits and
SRAMs are fast and accurate compared to SPICE. Therefore, these analysis approaches
can be easily integrated in a VLSI design flow to analyze the radiation tolerance of such
circuits, and harden them early in the design flow. From 3D device-level analysis of the radiation
tolerance of voltage scaled circuits, several non-intuitive observations are made and
correspondingly, a set of guidelines are proposed, which are important to consider to realize
radiation hardened circuits. Two circuit level hardening approaches are also presented
to harden combinational circuits against a radiation particle strike. These hardening approaches
significantly improve the tolerance of combinational circuits against low and very
high energy radiation particle strikes respectively, with modest area and delay overheads.
The second part of this dissertation addresses process variations. A technique is developed
to perform sensitizable statistical timing analysis of a circuit, and thereby improve the
accuracy of timing analysis under process variations. Experimental results demonstrate that
this technique is able to significantly reduce the pessimism due to two sources of inaccuracy
which plague current statistical static timing analysis (SSTA) tools. Two design approaches
are also proposed to improve the process variation tolerance of combinational circuits and
voltage level shifters (which are used in circuits with multiple interacting power supply
domains), respectively. The variation tolerant design approach for combinational circuits
significantly improves the resilience of these circuits to random process variations, with a
reduction in the worst case delay and low area penalty. The proposed voltage level shifter
is faster, requires lower dynamic power and area, has lower leakage currents, and is more
tolerant to process variations, compared to the best known previous approach.
In summary, this dissertation presents several analysis and design techniques which
significantly augment the existing work in the area of resilient VLSI circuit design
Dependability assessment of by-wire control systems using fault injection
This paper is focused on the validation by means of physical fault injection at pin-level of a time-triggered communication controller: the TTP/C versions C1 and C2. The controller is a commercial off-the-shelf product used in the design of by-wire systems. Drive-by-wire and fly-by-wire active safety controls aim to prevent accidents. They are considered to be of critical importance because a serious situation may directly affect user safety. Therefore, dependability assessment is vital in their design.
This work was funded by the European project `Fault Injection for TTA¿ and it is divided into two parts. In the first part, there is a verification of the dependability specifications of the TTP communication protocol, based on TTA, in the presence of faults directly induced in communication lines. The second part contains a validation and improvement proposal for the architecture in case of data errors. Such errors are due to faults that occurred during writing (or reading) actions on memory or during data storage.Blanc Clavero, S.; Bonastre Pina, AM.; Gil, P. (2009). Dependability assessment of by-wire control systems using fault injection. Journal of Systems Architecture. 55(2):102-113. doi:10.1016/j.sysarc.2008.09.003S10211355
Innovative Techniques for Testing and Diagnosing SoCs
We rely upon the continued functioning of many electronic devices for our everyday welfare,
usually embedding integrated circuits that are becoming even cheaper and smaller
with improved features. Nowadays, microelectronics can integrate a working computer
with CPU, memories, and even GPUs on a single die, namely System-On-Chip (SoC).
SoCs are also employed on automotive safety-critical applications, but need to be tested
thoroughly to comply with reliability standards, in particular the ISO26262 functional
safety for road vehicles.
The goal of this PhD. thesis is to improve SoC reliability by proposing innovative
techniques for testing and diagnosing its internal modules: CPUs, memories, peripherals,
and GPUs. The proposed approaches in the sequence appearing in this thesis are described
as follows:
1. Embedded Memory Diagnosis: Memories are dense and complex circuits which
are susceptible to design and manufacturing errors. Hence, it is important to understand
the fault occurrence in the memory array. In practice, the logical and physical
array representation differs due to an optimized design which adds enhancements to
the device, namely scrambling. This part proposes an accurate memory diagnosis
by showing the efforts of a software tool able to analyze test results, unscramble
the memory array, map failing syndromes to cell locations, elaborate cumulative
analysis, and elaborate a final fault model hypothesis. Several SRAM memory failing
syndromes were analyzed as case studies gathered on an industrial automotive
32-bit SoC developed by STMicroelectronics. The tool displayed defects virtually,
and results were confirmed by real photos taken from a microscope.
2. Functional Test Pattern Generation: The key for a successful test is the pattern applied
to the device. They can be structural or functional; the former usually benefits
from embedded test modules targeting manufacturing errors and is only effective
before shipping the component to the client. The latter, on the other hand, can be
applied during mission minimally impacting on performance but is penalized due
to high generation time. However, functional test patterns may benefit for having
different goals in functional mission mode. Part III of this PhD thesis proposes
three different functional test pattern generation methods for CPU cores embedded
in SoCs, targeting different test purposes, described as follows:
a. Functional Stress Patterns: Are suitable for optimizing functional stress during
I
Operational-life Tests and Burn-in Screening for an optimal device reliability
characterization
b. Functional Power Hungry Patterns: Are suitable for determining functional
peak power for strictly limiting the power of structural patterns during manufacturing
tests, thus reducing premature device over-kill while delivering high test
coverage
c. Software-Based Self-Test Patterns: Combines the potentiality of structural patterns
with functional ones, allowing its execution periodically during mission.
In addition, an external hardware communicating with a devised SBST was proposed.
It helps increasing in 3% the fault coverage by testing critical Hardly
Functionally Testable Faults not covered by conventional SBST patterns.
An automatic functional test pattern generation exploiting an evolutionary algorithm
maximizing metrics related to stress, power, and fault coverage was employed
in the above-mentioned approaches to quickly generate the desired patterns. The
approaches were evaluated on two industrial cases developed by STMicroelectronics;
8051-based and a 32-bit Power Architecture SoCs. Results show that generation
time was reduced upto 75% in comparison to older methodologies while
increasing significantly the desired metrics.
3. Fault Injection in GPGPU: Fault injection mechanisms in semiconductor devices
are suitable for generating structural patterns, testing and activating mitigation techniques,
and validating robust hardware and software applications. GPGPUs are
known for fast parallel computation used in high performance computing and advanced
driver assistance where reliability is the key point. Moreover, GPGPU manufacturers
do not provide design description code due to content secrecy. Therefore,
commercial fault injectors using the GPGPU model is unfeasible, making radiation
tests the only resource available, but are costly. In the last part of this thesis, we
propose a software implemented fault injector able to inject bit-flip in memory elements
of a real GPGPU. It exploits a software debugger tool and combines the
C-CUDA grammar to wisely determine fault spots and apply bit-flip operations in
program variables. The goal is to validate robust parallel algorithms by studying
fault propagation or activating redundancy mechanisms they possibly embed. The
effectiveness of the tool was evaluated on two robust applications: redundant parallel
matrix multiplication and floating point Fast Fourier Transform
Reliability Analysis of Electrotechnical Devices
This is a book on the practical approaches of reliability to electrotechnical devices and systems. It includes the electromagnetic effect, radiation effect, environmental effect, and the impact of the manufacturing process on electronic materials, devices, and boards
Reliability and Data Analysis of Wearout Mechanisms for Circuits
The objective of this research is to develop methodologies for the failure analysis of circuits, as well as investigate the factors for accelerating testing for front-end-of-line time-dependent dielectric breakdown (FEOL TDDB). The separation of wearout mechanisms for circuits will be investigated, and the identification of failure modes for the failure samples will be analyzed. SRAMs and ring oscillators will be used to study the failure modes. The systematic and random errors for online monitoring of SRAMS will also be examined. Furthermore, the testing plans for acceleration testing will also be explored for ring oscillators. Error reduction through sampling will also be used to find the best testing conditions for accelerated testing. This work provides a way for engineers to better understand aging monitoring of circuits, and to design better testing to collect failure data.Ph.D
The effects of ionising radiation on implantable MOS electronic devices
Space exploration and the rapid growth of the satellite communications industry has
promoted substantial research into the effects of ionising radiation on modem electronic
technology. The enabling electronics and computer processing has seen a commensurate
growth in the use of radiation for diagnostic and therapeutic purposes in medicine.
Numerous studies exist in both these fields but an analysis combining the fields of study
to ascertain the effects of radiation on medically implantable electronics is lacking.
A review of significant ground level radiation sources is presented with particular
emphasis on the medical environment. Mechanisms of permanent and transient ionising
radiation damage to Metal Oxide Semiconductors are summarised. Three significant
sources of radiation are classified as having the ability to damage or alter the behavior
of implantable electronics; Secondary neutron cosmic radiation, alpha particle radiation
from the device packaging and therapeutic doses of high energy radiation.
With respect to cosmic radiation, the most sensitive circuit structure within a typical
microcomputer architecture is the Random Access Memory(RAM). A theoretical model
which predicts the susceptibility of a RAM cell to single event upsets from secondary
cosmic ray neutrons is presented. A previously unreported method for calculating the
collection efficiency term in the upset model has been derived along with an extension
of the model to enable estimation of multiple bit upset rates.
An Implantable Cardioverter Defibrillator is used as a case example to demonstrate
model applicability and test against clinical experience. The model correlates well with
clinical experience and is consistent with the expected geographical variations of the
secondary cosmic ray neutron flux. This is the first clinical data set obtained indicating
the effects of cosmic radiation on implantable devices. Importantly, it may be used to
predict the susceptibility of future implantable device designs to cosmic radiation.
The model is also used as a basis for developing radiation hardened circuit techniques
and system design. A review of methods to radiation harden electronics to single event
upsets is used to recommend methods applicable to the low power/small area
constraints of implantable systems
Reliable Software for Unreliable Hardware - A Cross-Layer Approach
A novel cross-layer reliability analysis, modeling, and optimization approach is proposed in this thesis that leverages multiple layers in the system design abstraction (i.e. hardware, compiler, system software, and application program) to exploit the available reliability enhancing potential at each system layer and to exchange this information across multiple system layers
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