A Metaheuristic Method for Fast Multi-Deck Legalization

Department of Electrical EngineeringIn the field of circuit design, decreasing the transistor size is getting harder and harder. Hence, improving the circuit performance also becoming difficult. For the better circuit performance, various technologies are being tired and multi-deck standard cell technology is one of them. The standard cell methodology is a fundamental structure of EDA (Electric Design Automation). Using the standard cell library, EDA tools can easily design, and optimize the physical design of chips. In order to conventional standard cell, multi-deck standard cell occupies multiple rows on the chip. This multiple occupation increases complexity of the circuit physical design for EDA tools. Thus, legalization problem has become more challenging for the multi-deck standard cells. Recently, various multi-deck legalization methods are proposed because the conventional single-deck legalization method is not effective for multi-deck legalization. A state-of-the-arts legalization method is based on quadratic programming with the linear complementary problem(LCP). However, these previous researches can only cover the double-deck case because of runtime burden. In this thesis, we propose the fast and enhanced the multi-deck standard cell legalization algorithm which can handle higher than double-deck standard cell cases. The proposed legalization method achieves the most fastest runtime result for the dominant number of benchmarks on ICCAD Contest 2017 [1] compared with Top 3 results.ope

Método para legalização de circuitos com células de altura múltipla

Desde a década de 1970, novas tecnologias de semicondutores impactam nossa sociedade. Desde então, o número de componentes num mesmo circuito é dobrado a cada dois anos, seguindo a Lei de Moore. Com esse avanço, os microprocessadores atuais possuem bilhões de transistores nos seus circuitos. Porém, esses avanços impuseram regras de projeto que trouxeram novos desafios para as etapas de otimização. Para auxiliar nesses obstáculos foi preciso utilizar softwares de EDA (do inglês Eletronic Design Automation). Hoje em dia, as ferramentas EDA são usadas em projetos de fluxo de células padrão desde seus estágios iniciais até finais. O fluxo de células padrão é composto por uma sequência de fluxos para elaborar e sintetizar o circuito. Dentre estes fluxo está o fluxo da síntese, onde está a etapa de posicionamento. Uma das etapas do posicionamento é a legaliza ção cujo objetivo é mover as células para posições válidas e remover suas sobreposições. A legalização possui desafios como o número de células, células de altura mista, rote abilidade, comprimento de fio, regras de projeto complexas como regiões de fence. Os métodos de legalização são categorizados em heurísticos e analíticos para enfrentar esses desafios. Neste trabalho, é proposto um método heurístico de legalização de células de altura mista. Este trabalho foi baseado em etapas de trabalhos existentes na literatura. Além disso, nossa legalização é aplicada incrementalmente através de etapas que priorizam as células que violam suas regiões, após isso prioriza grupos de células sobrepostas. Os experimentos realizados mostram que nosso método proposto permite reduzir mais do que 15% o tempo de execução e a diferença nos resultados é mínima em comprimento de fio.Since the 1970s, new semiconductor technologies have impacted our society. After that, the number of components in the same circuit is doubled every two years, following Moore’s Law. Today’s microprocessors have billions of transistors in their circuits with this advancement. However, these advances imposed design rules that brought new chal lenges to the optimization steps. EDA (Electronic Design Automation) software was nec essary to help with these obstacles. EDA tools use in standard cell flow designs from their initial to final stages. The standard cell flow comprises a sequence of flows to elaborate and synthesize the circuit. Among these flows is the physical synthesis flow, which is the placement step. One of the placement steps is legalization which aims to move cells to proper positions and remove their overlaps. Legalization has challenges like the number of cells, mixed-cell height, routability, wirelength, and complex design rules like fence regions. Legalization methods are categorized into heuristic and analytical to address these challenges. This work proposes a heuristic method of legalization of mixed-height cells. This work is based on steps of existing works in the literature. Additionally, our legalization is applied incrementally through steps that prioritize cells that violate their regions, then prioritize groups of overlapping cells. The experiments show that our pro posed method allows us to reduce the execution time by more than 15%, and the difference in the results is minimal in terms of wirelength

Custom Cell Placement Automation for Asynchronous VLSI

Asynchronous Very-Large-Scale-Integration (VLSI) integrated circuits have demonstrated many advantages over their synchronous counterparts, including low power consumption, elastic pipelining, robustness against manufacturing and temperature variations, etc. However, the lack of dedicated electronic design automation (EDA) tools, especially physical layout automation tools, largely limits the adoption of asynchronous circuits. Existing commercial placement tools are optimized for synchronous circuits, and require a standard cell library provided by semiconductor foundries to complete the physical design. The physical layouts of cells in this library have the same height to simplify the placement problem and the power distribution network. Although the standard cell methodology also works for asynchronous designs, the performance is inferior compared with counterparts designed using the full-custom design methodology. To tackle this challenge, we propose a gridded cell layout methodology for asynchronous circuits, in which the cell height and cell width can be any integer multiple of two grid values. The gridded cell approach combines the shape regularity of standard cells with the size flexibility of full-custom layouts. Therefore, this approach can achieve a better space utilization ratio and lower wire length for asynchronous designs. Experiments have shown that the gridded cell placement approach reduces area without impacting the routability. We have also used this placer to tape out a chip in a 65nm process technology, demonstrating that our placer generates design-rule clean results

Improved Physical Design for Manufacturing Awareness and Advanced VLSI

Increasing challenges arise with each new semiconductor technology node, especially in advanced nodes, where the industry tries to extract every ounce of benefit as it approaches the limits of physics, through manufacturing-aware design technology co-optimization and design-based equivalent scaling. The increasing complexity of design and process technologies, and ever-more complex design rules, also become hurdles for academic researchers, separating academic researchers from the most up-to-date technical issues.This thesis presents innovative methodologies and optimizations to address the above challenges. There are three directions in this thesis: (i) manufacturing-aware design technology co-optimization; (ii) advanced node design-based equivalent scaling; and (iii) an open source academic detailed routing flow.To realize manufacturing-aware design technology co-optimization, this thesis presents two works: (i) a multi-row detailed placement optimization for neighbor diffusion effect mitigation between neighboring standard cells; and (ii) a post-routing optimization to generate 2D block mask layout for dummy segment removal in self-aligned multiple patterning.To achieve advanced node design-based equivalent scaling, this thesis presents two improved physical design methodologies: (i) a post-placement flop tray generation approach for clock power reduction; and (ii) a detailed placement approach to exploit inter-row M1 routing for congestion and wirelength reduction.To address the increasing gap between academia and industry, this thesis presents two works toward an open source academic detailed routing flow: (i) a complete, robust, scalable and design ruleaware dynamic programming-based pin access analysis framework; and (ii) TritonRoute – the open source detailed router that is capable of delivering DRC-clean detailed routing solutions in advanced nodes.This thesis concludes with a summary of its contributions and open directions for future research

Factors Affecting Land Titling during Regularization of Informal Settlements in Dar es Salaam Tanzania

The nature and characteristics of informal settlements in Tanzania indicates that informal landholders face a number of constraints attributable to weak land tenure security. In the beginning of 2016, the government undertook major initiatives to regularize informal settlements with limited success on land title uptake. This paper investigates the landholders’ willingness to change land tenure status and constraints faced thereof based on a dataset of 228 questionnaires, interviews and focus group discussions from informal settlements land occupiers in three wards of Dar es Salaam City, Tanzania. The findings indicate that despite a relatively lower rate of land title uptakes in the study areas, landholders are relatively more willing to change their land tenure status. Among the constraints identified include the costs and longer time taken to process the titles which were observed to be the most serious obstacles. Moreover, the oldest age group was observed to be the most reluctant age group to change tenure status when compared to relatively younger age groups although they were mostly aware of the benefits of changing tenure status. Furthermore, the findings indicate that, during title processing, the oldest age group faced the least constraints among the age groups studied. Since the oldest age group are the majority landholders, their reluctance to process title documents significantly reduces the number of title documents issued. In terms of education, the findings show that the highly educated groups have relatively lower willingness to change tenure status than other education groups. Such observation suggests that the more a landholder is educated, the more he or she is aware of the title benefit but the less likely him or her is to process a land title document. In terms of policy implication, for the poor class in informal settlement, regularization cost reduction could be an effective means to facilitate take up of land titles during regularization program though the same policy initiative may not work among the highly educated. For the highly educated and probably the rich, an informality tax could work, provided cheaper mechanisms to collect such tax are devised

Factors Affecting Land Titling during Regularization of Informal Settlements in Dar es Salaam Tanzania

The nature and characteristics of informal settlements in Tanzania indicates that informal landholders face a number of constraints attributable to weak land tenure security. In the beginning of 2016, the government undertook major initiatives to regularize informal settlements with limited success on land title uptake. This paper investigates the landholders’ willingness to change land tenure status and constraints faced thereof based on a dataset of 228 questionnaires, interviews and focus group discussions from informal settlements land occupiers in three wards of Dar es Salaam City, Tanzania. The findings indicate that despite a relatively lower rate of land title uptakes in the study areas, landholders are relatively more willing to change their land tenure status. Among the constraints identified include the costs and longer time taken to process the titles which were observed to be the most serious obstacles. Moreover, the oldest age group was observed to be the most reluctant age group to change tenure status when compared to relatively younger age groups although they were mostly aware of the benefits of changing tenure status. Furthermore, the findings indicate that, during title processing, the oldest age group faced the least constraints among the age groups studied. Since the oldest age group are the majority landholders, their reluctance to process title documents significantly reduces the number of title documents issued. In terms of education, the findings show that the highly educated groups have relatively lower willingness to change tenure status than other education groups. Such observation suggests that the more a landholder is educated, the more he or she is aware of the title benefit but the less likely him or her is to process a land title document. In terms of policy implication, for the poor class in informal settlement, regularization cost reduction could be an effective means to facilitate take up of land titles during regularization program though the same policy initiative may not work among the highly educated. For the highly educated and probably the rich, an informality tax could work, provided cheaper mechanisms to collect such tax are devised

2013 Annual Research Symposium Abstract Book

2013 annual volume of abstracts for science research projects conducted by students at Trinity College

New Land Use and Water Policy Geographies in Emerging Cannabis Markets: the Case of Pueblo County, Colorado

Voters and legislatures throughout the country are winding down the War on Drugs and legalizing marijuana for medical and retail use. While many regulatory decisions are made at state capitals nationwide, the marijuana landscape is largely shaped by local authorities exercising influence through land use planning. Over a decade after passing a voter-initiated medical marijuana program, Colorado voters approved a State Constitutional Amendment fully legalizing marijuana for adult use. The Regulate Marijuana like Alcohol Act of 2012 made Colorado the first state to legalize the sale, taxation, and possession of marijuana through a commercial market. Local governments were given the choice to permit or ban the cultivation and sale of marijuana within their jurisdictions, while also having the prerogative to use zoning to shape the market\u27s landscape. One local jurisdiction, Pueblo County, modified their existing land use regulations for medical marijuana cultivation and sale and permitted retail marijuana cultivation and sale mostly as a by-right land use throughout the County. Current federal policies have complicated the ability of cannabusiness owners to obtain legal water. This thesis explores the implications of new land use and water regulations placed upon the rapidly growing marijuana industry and will further assist in policy development as other states legalize marijuana. Qualitative research methods utilized in this thesis include content and relational analyses of zoning compliance information and interviews with County land use and zoning officials, water managers and regulators, and three licensed marijuana cultivators. Questions focused on the federal, state, and local policies that influence regulation and cannabusiness development and operations, as well as experiences acquiring zoning approval and a legal water supply. Findings include the basis for development of marijuana land use policies in Pueblo County, addressing security and other public land use concerns, water service concerns, challenges including federal water policy and the future of the emerging marijuana and hemp industries in Pueblo County. This thesis identifies considerations for evolving marijuana markets and recommendations for communities facing local land use questions in light of state-level legalization