15 research outputs found
Initial detailed routing algorithms
In this work, we present a study of the problem of routing in the context of the VLSI physical synthesis flow. We study the fundamental routing algorithms such as maze routing, A*, and Steiner tree-based algorithms, as well as some global routing algorithms, namely FastRoute 4.0 and BoxRouter 2.0. We dissect some of the major state of the art initial detailed routing tools, such as RegularRoute, TritonRoute, SmartDR and Dr.CU 2.0. We also propose an initial detailed routing flow, and present an implementation of the proposed routing flow, with a track assignment technique that models the problem as an instance of the maximum independent weighted set (MWIS) and utilizes integer linear programming (ILP) as a solver. The implementation of the proposed initial detailed routing flow also includes an implementation of multiple-source and multiple-target A* for terminal andnet connection with adjustable rules and weights. Finally, we also present a study of the results obtained by the implementation of the proposed initial detailed routing flow and a comparison with the ISPD 2019 contest winners, considering the ISPD 2019 and benchmark suite and evaluation tools.Neste trabalho, apresentamos um estudo do problema de roteamento no contexto do fluxo de sĂntese fĂsica de circuitos integrados VLSI. NĂłs estudamos algoritmos de roteamento fundamentais como roteamento de labirinto, A* e baseados em árvores de Steiner, alĂ©m de alguns algoritmos de roteamento global como FastRoute 4.0 e BoxRouter 2.0. NĂłs dissecamos alguns dos principais trabalhos de roteamento detalhado inicial do estado da arte, como RegularRoute, TritonRoute, SmartDR e Dr.CU 2.0. TambĂ©m propomos um fluxo de roteamento detalhado inicial, e apresentamos uma implementação do fluxo de roteametno proposto, com uma tĂ©cnica de assinalamento de trilhas que modela o problema como uma instância do problema do conjunto independente de peso máximo e usa programação linear inteira como um resolvedor. A implementação do fluxo de rotemaento detalhado inicial proposto tambĂ©m inclui uma implementação de um A* com mĂşltiplas fontes e mĂşltiplos destinos para conexĂŁo de terminais e redes, com regras e pesos ajustáveis. Por fim, nĂłs apresentamos um estudo dos resultados obtidos pela implementação do fluxo de roteamento detalhado inicial proposto e comparamos com os vencedores do ISPD 2019 contest considerando a suĂte de teste e ferramentas de avaliação do ISPD 2019
Monolithic integration of photonic devices for use in a regrowth-free coherent WDM transmitter
In this communication age, consumer internet traffic continues to grow at an exponential rate year on year. As a result, networks need to be continually upgraded to keep up with ever increasing bandwidth demands. Diverse research is currently being undertaken at a global level to produce cost effective solutions to maximize network performance. One such area focuses on the development of photonic integrated circuits (PICs), striving to replicated the same compact design and low power consumption achieved in the electronics industry. However, photonic components are more complex and diverse than their electrical equivalents, such as transistors. As these components can have large footprints, involve multiple electrical contacts and require different material properties for optimal performance, the best approach is not obvious when cost is considered. While platforms such as heterogenous integration and monolithic regrowth have produced PICs with advance functionality, they rely on complex fabrication processes which increase production time and cost. As a result, this thesis proposes a monolithic regrowth-free design for a coherent WDM transmitter which requires less sophisticated fabrication techniques and would therefore be more cost effective to manufacture than alternative methods. The work began with the development of suitable processes for the fabrication of DC and high-speed components associated with the transmitter. Utilizing the associated composite hard mask process, the integration of core components required for the coherent WDM transmitter was undertaken. The monolithic integration of a 1x2 multimode interference coupler, two slotted Fabry-Perot (SFP) lasers, two electroabsorption modulators (EAMs) and a star coupler was demonstrated using regrowth free epitaxy and UV contact lithography. The feasibility of integrating an SFP laser with an EAM by means of injection locking was also investigated, resulting in the production of a 2.5 Gbps eye diagram. It was shown that the high-speed performance of these PICs could be improved by using more advanced modulator designs. As a result, this thesis concludes with an investigation of high speed modulators with the aim of to increase the data rate of the developed PICs. An integratable electroabsorption modulator with a 3 dB bandwidth of 17.5 GHz and a corresponding 12.5 Gbps eye diagram was realized
Simulated Annealing
The book contains 15 chapters presenting recent contributions of top researchers working with Simulated Annealing (SA). Although it represents a small sample of the research activity on SA, the book will certainly serve as a valuable tool for researchers interested in getting involved in this multidisciplinary field. In fact, one of the salient features is that the book is highly multidisciplinary in terms of application areas since it assembles experts from the fields of Biology, Telecommunications, Geology, Electronics and Medicine
Layoutautomatisierung im analogen IC-Entwurf mit formalisiertem und nicht-formalisiertem Expertenwissen
After more than three decades of electronic design automation, most layouts for analog integrated circuits are still handcrafted in a laborious manual fashion today. Obverse to the highly automated synthesis tools in the digital domain (coping with the quantitative difficulty of packing more and more components onto a single chip – a desire well known as More Moore), analog layout automation struggles with the many diverse and heavily correlated functional requirements that turn the analog design problem into a More than Moore challenge. Facing this qualitative complexity, seasoned layout engineers rely on their comprehensive expert knowledge to consider all design constraints that uncompromisingly need to be satisfied. This usually involves both formally specified and nonformally communicated pieces of expert knowledge, which entails an explicit and implicit consideration of design constraints, respectively.
Existing automation approaches can be basically divided into optimization algorithms (where constraint consideration occurs explicitly) and procedural generators (where constraints can only be taken into account implicitly). As investigated in this thesis, these two automation strategies follow two fundamentally different paradigms denoted as top-down automation and bottom-up automation. The major trait of top-down automation is that it requires a thorough formalization of the problem to enable a self-intelligent solution finding, whereas a bottom-up automatism –controlled by parameters– merely reproduces solutions that have been preconceived by a layout expert in advance. Since the strengths of one paradigm may compensate the weaknesses of the other, it is assumed that a combination of both paradigms –called bottom-up meets top-down– has much more potential to tackle the analog design problem in its entirety than either optimization-based or generator-based approaches alone.
Against this background, the thesis at hand presents Self-organized Wiring and Arrangement of Responsive Modules (SWARM), an interdisciplinary methodology addressing the design problem with a decentralized multi-agent system. Its basic principle, similar to the roundup of a sheep herd, is to let responsive mobile layout modules (implemented as context-aware procedural generators) interact with each other inside a user-defined layout zone. Each module is allowed to autonomously move, rotate and deform itself, while a supervising control organ successively tightens the layout zone to steer the interaction towards increasingly compact (and constraint compliant) layout arrangements. Considering various principles of self-organization and incorporating ideas from existing decentralized systems, SWARM is able to evoke the phenomenon of emergence: although each module only has a limited viewpoint and selfishly pursues its personal objectives, remarkable overall solutions can emerge on the global scale.
Several examples exhibit this emergent behavior in SWARM, and it is particularly interesting that even optimal solutions can arise from the module interaction. Further examples demonstrate SWARM’s suitability for floorplanning purposes and its application to practical place-and-route problems. The latter illustrates how the interacting modules take care of their respective design requirements implicitly (i.e., bottom-up) while simultaneously paying respect to high level constraints (such as the layout outline imposed top-down by the supervising control organ). Experimental results show that SWARM can outperform optimization algorithms and procedural generators both in terms of layout quality and design productivity. From an academic point of view, SWARM’s grand achievement is to tap fertile virgin soil for future works on novel bottom-up meets top-down automatisms. These may one day be the key to close the automation gap in analog layout design.Nach mehr als drei Jahrzehnten Entwurfsautomatisierung werden die meisten Layouts für analoge integrierte Schaltkreise heute immer noch in aufwändiger Handarbeit entworfen. Gegenüber den hochautomatisierten Synthesewerkzeugen im Digitalbereich (die sich mit dem quantitativen Problem auseinandersetzen, mehr und mehr Komponenten auf einem einzelnen Chip unterzubringen – bestens bekannt als More Moore) kämpft die analoge Layoutautomatisierung mit den vielen verschiedenen und stark korrelierten funktionalen Anforderungen, die das analoge Entwurfsproblem zu einer More than Moore Herausforderung machen. Angesichts dieser qualitativen Komplexität bedarf es des umfassenden Expertenwissens erfahrener Layouter um sämtliche Entwurfsconstraints, die zwingend eingehalten werden müssen, zu berücksichtigen. Meist beinhaltet dies formal spezifiziertes als auch nicht-formal übermitteltes Expertenwissen, was eine explizite bzw. implizite Constraint Berücksichtigung nach sich zieht.
Existierende Automatisierungsansätze können grundsätzlich unterteilt werden in Optimierungsalgorithmen (wo die Constraint Berücksichtigung explizit erfolgt) und prozedurale Generatoren (die Constraints nur implizit berücksichtigen können). Wie in dieser Arbeit eruiert wird, folgen diese beiden Automatisierungsstrategien zwei grundlegend unterschiedlichen Paradigmen, bezeichnet als top-down Automatisierung und bottom-up Automatisierung. Wesentliches Merkmal der top-down Automatisierung ist die Notwendigkeit einer umfassenden Problemformalisierung um eine eigenintelligente Lösungsfindung zu ermöglichen, während ein bottom-up Automatismus –parametergesteuert– lediglich Lösungen reproduziert, die vorab von einem Layoutexperten vorgedacht wurden. Da die Stärken des einen Paradigmas die Schwächen des anderen ausgleichen können, ist anzunehmen, dass eine Kombination beider Paradigmen –genannt bottom-up meets top down– weitaus mehr Potenzial hat, das analoge Entwurfsproblem in seiner Gesamtheit zu lösen als optimierungsbasierte oder generatorbasierte Ansätze für sich allein. Vor diesem Hintergrund stellt die vorliegende Arbeit Self-organized Wiring and Arrangement of Responsive Modules (SWARM) vor, eine interdisziplinäre Methodik, die das Entwurfsproblem mit einem dezentralisierten Multi-Agenten-System angeht. Das Grundprinzip besteht darin, ähnlich dem Zusammentreiben einer Schafherde, reaktionsfähige mobile Layoutmodule (realisiert als kontextbewusste prozedurale Generatoren) in einer benutzerdefinierten Layoutzone interagieren zu lassen. Jedes Modul darf sich selbständig bewegen, drehen und verformen, wobei ein übergeordnetes Kontrollorgan die Zone schrittweise verkleinert, um die Interaktion auf zunehmend kompakte (und constraintkonforme) Layoutanordnungen hinzulenken. Durch die Berücksichtigung diverser Selbstorganisationsgrundsätze und die Einarbeitung von Ideen bestehender dezentralisierter Systeme ist SWARM in der Lage, das Phänomen der Emergenz hervorzurufen: obwohl jedes Modul nur eine begrenzte Sichtweise hat und egoistisch seine eigenen Ziele verfolgt, können sich auf globaler Ebene bemerkenswerte Gesamtlösungen herausbilden.
Mehrere Beispiele veranschaulichen dieses emergente Verhalten in SWARM, wobei besonders interessant ist, dass sogar optimale Lösungen aus der Modulinteraktion entstehen können. Weitere Beispiele demonstrieren SWARMs Eignung zwecks Floorplanning sowie die Anwendung auf praktische Place-and-Route Probleme. Letzteres verdeutlicht, wie die interagierenden Module ihre jeweiligen Entwurfsanforderungen implizit (also: bottom-up) beachten, während sie gleichzeitig High-Level-Constraints berücksichtigen (z.B. die Layoutkontur, die top-down vom übergeordneten Kontrollorgan auferlegt wird). Experimentelle Ergebnisse zeigen, dass Optimierungsalgorithmen und prozedurale Generatoren von SWARM sowohl bezüglich Layoutqualität als auch Entwurfsproduktivität übertroffen werden können. Aus akademischer Sicht besteht SWARMs große Errungenschaft in der Erschließung fruchtbaren Neulands für zukünftige Arbeiten an neuartigen bottom-up meets top-down Automatismen. Diese könnten eines Tages der Schlüssel sein, um die Automatisierungslücke im analogen Layoutentwurf zu schließen
A prototype Cylindrical And Tiny Spectrometer for the rapid energy analysis of space plasmas
Miniaturised space plasma analysers allow for lower cost plasma measurements for space science and for space weather monitoring applications; further miniaturisation will make possible nanosat-scale plasma instruments. Small instruments produced in large numbers are ideal for very-large-scale swarm and constellation missions. The field of MEMS (micro-electro-mechanical systems) potentially enables all these possibilities. This thesis introduces these themes and describes the conception and development of CATS (Cylindrical And Tiny Spectrometer), an instrument designed with MEMS in mind. CATS uses an innovative, highly-miniaturised, concentric cylindrical geometry that is able to measure simultaneously, multiple energies of both electrons and ions in space plasmas. A prototype of a CATS analyser head has been fabricated – the critical electrodes by electron discharge machining – and has been demonstrated with 30 eV to 8 keV electrons in a laboratory environment. A CEM (channel electron multiplier) and a CCD (charge coupled device) have been adapted for use with the prototype. The CCD is a back-illuminated, ion-implanted device that has been used to detect electrons directly—the first known use of such a device in an analyser instrument. The prototype design has also been extensively modelled using SIMION charged particle ray-tracing simulations, run within a tool-kit of specially created and highly sophisticated IDL automation and analysis routines. This has revealed the focussing properties of the design and options for improvements. The experimental results were compared with the simulation results and discrepancies were revealed that suggested deviations from the design specification. These deviations were confirmed, in part, by a visual inspection. Recommendations for future work and possible applications of the instrument are discussed, including the destination of the current CATS prototype and CCD detector: PoleCATS, a student-led, educational project to develop a low-altitude sounding rocket instrument
"Knowing is Seeing:" The Digital Audio Workstation and the Visualization of Sound
The computers visual representation of sound has revolutionized the creation of music through the interface of the Digital Audio Workstation software (DAW). With the rise of DAW-based composition in popular music styles, many artists sole experience of musical creation is through the computer screen. I assert that the particular sonic visualizations of the DAW propagate certain assumptions about music, influencing aesthetics and adding new visually-based parameters to the creative process. I believe many of these new parameters are greatly indebted to the visual structures, interactional dictates and standardizations (such as the office metaphor depicted by operating systems such as Apples OS and Microsofts Windows) of the Graphical User Interface (GUI). Whether manipulating text, video or audio, a users interaction with the GUI is usually structured in the same mannerclicking on windows, icons and menus with a mouse-driven cursor. Focussing on the dialogs from the Reddit communities of Making hip-hop and EDM production, DAW user manuals, as well as interface design guidebooks, this dissertation will address the ways these visualizations and methods of working affect the workflow, composition style and musical conceptions of DAW-based producers