374 research outputs found
Custom Integrated Circuits
Contains reports on ten research projects.Analog Devices, Inc.IBM CorporationNational Science Foundation/Defense Advanced Research Projects Agency Grant MIP 88-14612Analog Devices Career Development Assistant ProfessorshipU.S. Navy - Office of Naval Research Contract N0014-87-K-0825AT&TDigital Equipment CorporationNational Science Foundation Grant MIP 88-5876
Testability Analysis and Improvements of Register-Transfer Level Digital Circuits
The paper presents novel testability analysis method applicable to register-transfer level digital circuits. It is shown if each module stored in a design library is equipped both with information related to design and information related to testing, then more accurate testability results can be achieved. A mathematical model based on virtual port conception is utilized to describe the information and proposed testability analysis method. In order to be effective, the method is based on the idea of searching two special digraphs developed for the purpose. Experimental results gained by the method are presented and compared with results of existing methods
Transient error mitigation by means of approximate logic circuits
Mención Internacional en el tÃtulo de doctorThe technological advances in the manufacturing of electronic circuits have allowed to
greatly improve their performance, but they have also increased the sensitivity of electronic
devices to radiation-induced errors. Among them, the most common effects are
the SEEs, i.e., electrical perturbations provoked by the strike of high-energy particles,
which may modify the internal state of a memory element (SEU) or generate erroneous
transient pulses (SET), among other effects. These events pose a threat for the reliability
of electronic circuits, and therefore fault-tolerance techniques must be applied to
deal with them.
The most common fault-tolerance techniques are based in full replication (DWC or
TMR). These techniques are able to cover a wide range of failure mechanisms present
in electronic circuits. However, they suffer from high overheads in terms of area and
power consumption. For this reason, lighter alternatives are often sought at the expense
of slightly reducing reliability for the least critical circuit sections. In this context a new
paradigm of electronic design is emerging, known as approximate computing, which
is based on improving the circuit performance in change of slight modifications of the
intended functionality. This is an interesting approach for the design of lightweight
fault-tolerant solutions, which has not been yet studied in depth.
The main goal of this thesis consists in developing new lightweight fault-tolerant
techniques with partial replication, by means of approximate logic circuits. These
circuits can be designed with great flexibility. This way, the level of protection as
well as the overheads can be adjusted at will depending on the necessities of each
application. However, finding optimal approximate circuits for a given application is
still a challenge.
In this thesis a method for approximate circuit generation is proposed, denoted
as fault approximation, which consists in assigning constant logic values to specific
circuit lines. On the other hand, several criteria are developed to generate the most
suitable approximate circuits for each application, by using this fault approximation
mechanism. These criteria are based on the idea of approximating the least testable
sections of circuits, which allows reducing overheads while minimising the loss of reliability.
Therefore, in this thesis the selection of approximations is linked to testability
measures.
The first criterion for fault selection developed in this thesis uses static testability
measures. The approximations are generated from the results of a fault simulation of
the target circuit, and from a user-specified testability threshold. The amount of approximated
faults depends on the chosen threshold, which allows to generate approximate circuits with different performances. Although this approach was initially intended for
combinational circuits, an extension to sequential circuits has been performed as well,
by considering the flip-flops as both inputs and outputs of the combinational part of
the circuit. The experimental results show that this technique achieves a wide scalability,
and an acceptable trade-off between reliability versus overheads. In addition, its
computational complexity is very low.
However, the selection criterion based in static testability measures has some drawbacks.
Adjusting the performance of the generated approximate circuits by means of
the approximation threshold is not intuitive, and the static testability measures do not
take into account the changes as long as faults are approximated. Therefore, an alternative
criterion is proposed, which is based on dynamic testability measures. With this
criterion, the testability of each fault is computed by means of an implication-based
probability analysis. The probabilities are updated with each new approximated fault,
in such a way that on each iteration the most beneficial approximation is chosen, that
is, the fault with the lowest probability. In addition, the computed probabilities allow
to estimate the level of protection against faults that the generated approximate circuits
provide. Therefore, it is possible to generate circuits which stick to a target error rate.
By modifying this target, circuits with different performances can be obtained. The
experimental results show that this new approach is able to stick to the target error rate
with reasonably good precision. In addition, the approximate circuits generated with
this technique show better performance than with the approach based in static testability
measures. In addition, the fault implications have been reused too in order to
implement a new type of logic transformation, which consists in substituting functionally
similar nodes.
Once the fault selection criteria have been developed, they are applied to different
scenarios. First, an extension of the proposed techniques to FPGAs is performed,
taking into account the particularities of this kind of circuits. This approach has been
validated by means of radiation experiments, which show that a partial replication with
approximate circuits can be even more robust than a full replication approach, because
a smaller area reduces the probability of SEE occurrence. Besides, the proposed
techniques have been applied to a real application circuit as well, in particular to the
microprocessor ARM Cortex M0. A set of software benchmarks is used to generate
the required testability measures. Finally, a comparative study of the proposed approaches
with approximate circuit generation by means of evolutive techniques have
been performed. These approaches make use of a high computational capacity to generate
multiple circuits by trial-and-error, thus reducing the possibility of falling into
local minima. The experimental results demonstrate that the circuits generated with
evolutive approaches are slightly better in performance than the circuits generated with
the techniques here proposed, although with a much higher computational effort.
In summary, several original fault mitigation techniques with approximate logic
circuits are proposed. These approaches are demonstrated in various scenarios, showing
that the scalability and adaptability to the requirements of each application are their
main virtuesLos avances tecnológicos en la fabricación de circuitos electrónicos han permitido mejorar
en gran medida sus prestaciones, pero también han incrementado la sensibilidad
de los mismos a los errores provocados por la radiación. Entre ellos, los más comunes
son los SEEs, perturbaciones eléctricas causadas por el impacto de partÃculas de alta
energÃa, que entre otros efectos pueden modificar el estado de los elementos de memoria
(SEU) o generar pulsos transitorios de valor erróneo (SET). Estos eventos suponen
un riesgo para la fiabilidad de los circuitos electrónicos, por lo que deben ser tratados
mediante técnicas de tolerancia a fallos.
Las técnicas de tolerancia a fallos más comunes se basan en la replicación completa
del circuito (DWC o TMR). Estas técnicas son capaces de cubrir una amplia variedad
de modos de fallo presentes en los circuitos electrónicos. Sin embargo, presentan un
elevado sobrecoste en área y consumo. Por ello, a menudo se buscan alternativas más
ligeras, aunque no tan efectivas, basadas en una replicación parcial. En este contexto
surge una nueva filosofÃa de diseño electrónico, conocida como computación aproximada,
basada en mejorar las prestaciones de un diseño a cambio de ligeras modificaciones
de la funcionalidad prevista. Es un enfoque atractivo y poco explorado para el diseño
de soluciones ligeras de tolerancia a fallos.
El objetivo de esta tesis consiste en desarrollar nuevas técnicas ligeras de tolerancia
a fallos por replicación parcial, mediante el uso de circuitos lógicos aproximados. Estos
circuitos se pueden diseñar con una gran flexibilidad. De este forma, tanto el nivel de
protección como el sobrecoste se pueden regular libremente en función de los requisitos
de cada aplicación. Sin embargo, encontrar los circuitos aproximados óptimos para
cada aplicación es actualmente un reto.
En la presente tesis se propone un método para generar circuitos aproximados, denominado
aproximación de fallos, consistente en asignar constantes lógicas a ciertas
lÃneas del circuito. Por otro lado, se desarrollan varios criterios de selección para, mediante
este mecanismo, generar los circuitos aproximados más adecuados para cada
aplicación. Estos criterios se basan en la idea de aproximar las secciones menos testables
del circuito, lo que permite reducir los sobrecostes minimizando la perdida de
fiabilidad. Por tanto, en esta tesis la selección de aproximaciones se realiza a partir de
medidas de testabilidad.
El primer criterio de selección de fallos desarrollado en la presente tesis hace uso de
medidas de testabilidad estáticas. Las aproximaciones se generan a partir de los resultados
de una simulación de fallos del circuito objetivo, y de un umbral de testabilidad
especificado por el usuario. La cantidad de fallos aproximados depende del umbral escogido, lo que permite generar circuitos aproximados con diferentes prestaciones.
Aunque inicialmente este método ha sido concebido para circuitos combinacionales,
también se ha realizado una extensión a circuitos secuenciales, considerando los biestables
como entradas y salidas de la parte combinacional del circuito. Los resultados
experimentales demuestran que esta técnica consigue una buena escalabilidad, y unas
prestaciones de coste frente a fiabilidad aceptables. Además, tiene un coste computacional
muy bajo.
Sin embargo, el criterio de selección basado en medidas estáticas presenta algunos
inconvenientes. No resulta intuitivo ajustar las prestaciones de los circuitos aproximados
a partir de un umbral de testabilidad, y las medidas estáticas no tienen en cuenta los
cambios producidos a medida que se van aproximando fallos. Por ello, se propone un
criterio alternativo de selección de fallos, basado en medidas de testabilidad dinámicas.
Con este criterio, la testabilidad de cada fallo se calcula mediante un análisis de probabilidades
basado en implicaciones. Las probabilidades se actualizan con cada nuevo
fallo aproximado, de forma que en cada iteración se elige la aproximación más favorable,
es decir, el fallo con menor probabilidad. Además, las probabilidades calculadas
permiten estimar la protección frente a fallos que ofrecen los circuitos aproximados
generados, por lo que es posible generar circuitos que se ajusten a una tasa de fallos
objetivo. Modificando esta tasa se obtienen circuitos aproximados con diferentes prestaciones.
Los resultados experimentales muestran que este método es capaz de ajustarse
razonablemente bien a la tasa de fallos objetivo. Además, los circuitos generados
con esta técnica muestran mejores prestaciones que con el método basado en medidas
estáticas. También se han aprovechado las implicaciones de fallos para implementar
un nuevo tipo de transformación lógica, consistente en sustituir nodos funcionalmente
similares.
Una vez desarrollados los criterios de selección de fallos, se aplican a distintos
campos. En primer lugar, se hace una extensión de las técnicas propuestas para FPGAs,
teniendo en cuenta las particularidades de este tipo de circuitos. Esta técnica se ha validado
mediante experimentos de radiación, los cuales demuestran que una replicación
parcial con circuitos aproximados puede ser incluso más robusta que una replicación
completa, ya que un área más pequeña reduce la probabilidad de SEEs. Por otro lado,
también se han aplicado las técnicas propuestas en esta tesis a un circuito de aplicación
real, el microprocesador ARM Cortex M0, utilizando un conjunto de benchmarks
software para generar las medidas de testabilidad necesarias. Por ´último, se realiza un
estudio comparativo de las técnicas desarrolladas con la generación de circuitos aproximados
mediante técnicas evolutivas. Estas técnicas hacen uso de una gran capacidad
de cálculo para generar múltiples circuitos mediante ensayo y error, reduciendo la posibilidad
de caer en algún mÃnimo local. Los resultados confirman que, en efecto, los
circuitos generados mediante técnicas evolutivas son ligeramente mejores en prestaciones
que con las técnicas aquà propuestas, pero con un coste computacional mucho
mayor.
En definitiva, se proponen varias técnicas originales de mitigación de fallos mediante
circuitos aproximados. Se demuestra que estas técnicas tienen diversas aplicaciones,
haciendo de la flexibilidad y adaptabilidad a los requisitos de cada aplicación
sus principales virtudes.Programa Oficial de Doctorado en IngenierÃa Eléctrica, Electrónica y AutomáticaPresidente: Raoul Velazco.- Secretario: Almudena Lindoso Muñoz.- Vocal: Jaume Segura Fuste
Custom Integrated Circuits
Contains reports on twelve research projects.Analog Devices, Inc.International Business Machines, Inc.Joint Services Electronics Program (Contract DAAL03-86-K-0002)Joint Services Electronics Program (Contract DAAL03-89-C-0001)U.S. Air Force - Office of Scientific Research (Grant AFOSR 86-0164)Rockwell International CorporationOKI Semiconductor, Inc.U.S. Navy - Office of Naval Research (Contract N00014-81-K-0742)Charles Stark Draper LaboratoryNational Science Foundation (Grant MIP 84-07285)National Science Foundation (Grant MIP 87-14969)Battelle LaboratoriesNational Science Foundation (Grant MIP 88-14612)DuPont CorporationDefense Advanced Research Projects Agency/U.S. Navy - Office of Naval Research (Contract N00014-87-K-0825)American Telephone and TelegraphDigital Equipment CorporationNational Science Foundation (Grant MIP-88-58764
Analysis of Hardware Descriptions
The design process for integrated circuits requires a lot of analysis of circuit descriptions. An important class of analyses determines how easy it will be to determine if a physical component suffers from any manufacturing errors. As circuit complexities grow rapidly, the problem of testing circuits also becomes increasingly difficult. This thesis explores the potential for analysing a recent high level hardware description language called Ruby. In particular, we are interested in performing testability analyses of Ruby circuit descriptions. Ruby is ammenable to algebraic manipulation, so we have sought transformations that improve testability while preserving behaviour. The analysis of Ruby descriptions is performed by adapting a technique called abstract interpretation. This has been used successfully to analyse functional programs. This technique is most applicable where the analysis to be captured operates over structures isomorphic to the structure of the circuit. Many digital systems analysis tools require the circuit description to be given in some special form. This can lead to inconsistency between representations, and involves additional work converting between representations. We propose using the original description medium, in this case Ruby, for performing analyses. A related technique, called non-standard interpretation, is shown to be very useful for capturing many circuit analyses. An implementation of a system that performs non-standard interpretation forms the central part of the work. This allows Ruby descriptions to be analysed using alternative interpretations such test pattern generation and circuit layout interpretations. This system follows a similar approach to Boute's system semantics work and O'Donnell's work on Hydra. However, we have allowed a larger class of interpretations to be captured and offer a richer description language. The implementation presented here is constructed to allow a large degree of code sharing between different analyses. Several analyses have been implemented including simulation, test pattern generation and circuit layout. Non-standard interpretation provides a good framework for implementing these analyses. A general model for making non-standard interpretations is presented. Combining forms that combine two interpretations to produce a new interpretation are also introduced. This allows complex circuit analyses to be decomposed in a modular manner into smaller circuit analyses which can be built independently
A test method for analog circuits : using sensitivity analysis and the singular value decomposition
XVII+C.3hlm.;24c
Interconnect yield analysis and fault tolerance for field programmable gate arrays
Imperial Users onl
Efficient alternative wiring techniques and applications.
Sze, Chin Ngai.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.Includes bibliographical references (leaves 80-84) and index.Abstracts in English and Chinese.Abstract --- p.iAcknowledgments --- p.iiiCurriculum Vitae --- p.ivList of Figures --- p.ixList of Tables --- p.xiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivation and Aims --- p.1Chapter 1.2 --- Contribution --- p.8Chapter 1.3 --- Organization of Dissertation --- p.10Chapter 2 --- Definitions and Notations --- p.11Chapter 3 --- Literature Review --- p.15Chapter 3.1 --- Logic Reconstruction --- p.15Chapter 3.1.1 --- SIS: A System for Sequential and Combinational Logic Synthesis --- p.16Chapter 3.2 --- ATPG-based Alternative Wiring --- p.17Chapter 3.2.1 --- Redundancy Addition and Removal for Logic Optimization --- p.18Chapter 3.2.2 --- Perturb and Simplify Logic Optimization --- p.18Chapter 3.2.3 --- REWIRE --- p.21Chapter 3.2.4 --- Implication-tree Based Alternative Wiring Logic Trans- formation --- p.22Chapter 3.3 --- Graph-based Alternative Wiring --- p.24Chapter 4 --- Implication Based Alternative Wiring Logic Transformation --- p.25Chapter 4.1 --- Source Node Implication --- p.25Chapter 4.1.1 --- Introduction --- p.25Chapter 4.1.2 --- Implication Relationship and Implication-tree --- p.25Chapter 4.1.3 --- Selection of Alternative Wire Based on Implication-tree --- p.29Chapter 4.1.4 --- Implication-tree Based Logic Transformation --- p.32Chapter 4.2 --- Destination Node Implication --- p.35Chapter 4.2.1 --- Introduction --- p.35Chapter 4.2.2 --- Destination Node Relationship --- p.35Chapter 4.2.3 --- Destination Node Implication-tree --- p.39Chapter 4.2.4 --- Selection of Alternative Wire --- p.41Chapter 4.3 --- The Algorithm --- p.43Chapter 4.3.1 --- IB AW Implementation --- p.43Chapter 4.3.2 --- Experimental Results --- p.43Chapter 4.4 --- Conclusion --- p.45Chapter 5 --- Graph Based Alternative Wiring Logic Transformation --- p.47Chapter 5.1 --- Introduction --- p.47Chapter 5.2 --- Notations and Definitions --- p.48Chapter 5.3 --- Alternative Wire Patterns --- p.50Chapter 5.4 --- Construction of Minimal Patterns --- p.54Chapter 5.4.1 --- Minimality of Patterns --- p.54Chapter 5.4.2 --- Minimal Pattern Formation --- p.56Chapter 5.4.3 --- Pattern Extraction --- p.61Chapter 5.5 --- Experimental Results --- p.63Chapter 5.6 --- Conclusion --- p.63Chapter 6 --- Logic Optimization by GBAW --- p.66Chapter 6.1 --- Introduction --- p.66Chapter 6.2 --- Logic Simplification --- p.67Chapter 6.2.1 --- Single-Addition-Multiple-Removal by Pattern Feature . . --- p.67Chapter 6.2.2 --- Single-Addition-Multiple-Removal by Combination of Pat- terns --- p.68Chapter 6.2.3 --- Single-Addition-Single-Removal --- p.70Chapter 6.3 --- Incremental Perturbation Heuristic --- p.71Chapter 6.4 --- GBAW Optimization Algorithm --- p.73Chapter 6.5 --- Experimental Results --- p.73Chapter 6.6 --- Conclusion --- p.76Chapter 7 --- Conclusion --- p.78Bibliography --- p.80Chapter A --- VLSI Design Cycle --- p.85Chapter B --- Alternative Wire Patterns in [WLFOO] --- p.87Chapter B.1 --- 0-local Pattern --- p.87Chapter B.2 --- 1-local Pattern --- p.88Chapter B.3 --- 2-local Pattern --- p.89Chapter B.4 --- Fanout-reconvergent Pattern --- p.90Chapter C --- New Alternative Wire Patterns --- p.91Chapter C.1 --- Pattern Cluster C1 --- p.91Chapter C.1.1 --- NAND-NAND-AND/NAND;AND/NAND --- p.91Chapter C.1.2 --- NOR-NOR-OR/NOR;AND/NAND --- p.92Chapter C.1.3 --- AND-NOR-OR/NOR;OR/NOR --- p.95Chapter C.1.4 --- OR-NAND-AND/NAND;AND/NAND --- p.95Chapter C.2 --- Pattern Cluster C2 --- p.98Chapter C.3 --- Pattern Cluster C3 --- p.99Chapter C.4 --- Pattern Cluster C4 --- p.104Chapter C.5 --- Pattern Cluster C5 --- p.105Glossary --- p.106Index --- p.10
Rethinking Watermark: Providing Proof of IP Ownership in Modern SoCs
Intellectual property (IP) cores are essential to creating modern system-on-chips (SoCs). Protecting the IPs deployed in modern SoCs has become more difficult as the IP houses have been established across the globe over the past three decades. The threat posed by IP piracy and overuse has been a topic of research for the past decade or so and has led to creation of a field called watermarking. IP watermarking aims of detecting unauthorized IP usage by embedding excess, nonfunctional circuitry into the SoC. Unfortunately, prior work has been built upon assumptions that cannot be met within the modern SoC design and verification processes. In this paper, we first provide an extensive overview of the current state-of-the-art IP watermarking. Then, we challenge these dated assumptions and propose a new path for future effective IP watermarking approaches suitable for today\u27s complex SoCs in which IPs are deeply embedded
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