Highlevel area and power estimation for vlsi circuits. Effective and efficient routing algorithms are essential to handle the challenges arising from the fast growing scaling of ic integration. Fast congestion analysis prior to global routing enhances the placement quality and. Introduction minimizing the total routed wirelength is one of the fundamen tal goals in vlsi placemen t stage. Estimation and optimization provides the reader with a complete understanding of the root causes of routing congestion in presentday and future vlsi circuits, available techniques for estimating and optimizing this congestion, and a critical analysis of the accuracy and effectiveness of these techniques, so. Electrical engineering with highest honors university of illinois at urbanachampaign, 1992 submitted to the department of electrical engineering and computer science in partial fulfillment of the requirements for the degree of. A fast congestion estimator for routing with bounded. Manhattan routing has only been on a very small scale, however. Using the proposed congestion driven spanning trees cdst, and continuously analyzing the congestion at all steps, nets are incrementally globally. Performance driven routing for modern fpgas proceedings. Section vi presents our experimental setups and results.
Estimation and optimization integrated circuits and systems by prashant saxena 20101129 on. In physical design, the required routing resources are modeled by congestion, and placement and routing can sometimes fix, or avoid, potential congestion problems 89. Optimized routing methods for vlsi placement design. It is a consequence of the rising design complexity. Motivation interconnect dominance is a daunting issue for sub100 nm vlsi designs. May 31, 2012 routing is one of the most fundamental steps in the physical design flow and is typically a very complex optimization problem.
Routing is typically a very complex combinatorial problem. Routing congestion in vlsi circuits estimation and. Optimization of power consumption in vlsi circuit zamin ali khana,s. Placement overview placement seeks to determine the location of instances e. The estimation of routing congestion without a placement for a network is, if not impossible, liable to be highly inaccurate, and one may have to rely on high level metrics such as adhesion 6. Interconnect congestion estimation plays an important role in the physical design of integrated circuits. We can reduce the cell density at congested areas by using coordinate option. Sapatnekar university of minnesota minneapolis, mn, usa routing congestion in vlsi circuits. Power optimization and assessment of optimization using. Arteris networkonchip interconnect fabric ip allows soc designers to reduce and remove routing congestion in the architecture phase of design by reducing the number of interconnect wires that will need to be routed.
Bounding the efforts on congestion optimization for. Exp erimen ts on large industry circuits sho w that the early congestion estimation based on ren ts rule is a promising approac h. Congestion estimation during topdown placement computer. Estimation and optimization is a valuable reference for cad developers and researchers, design methodology engineers, vlsi design and cad students, and vlsi. To make it manageable, the routing problem is usually solved by use of a twostage approach of global routing followed by detailed routing. Our congestion metric calculation method considers the wire scenarios in a channel. In other words, ignoring routing congestion during earlier phases of physical design process may result in an unroutable circuit, especially in large and complex. We propose an accurate measure of channel routing density and its application to global routing. A global router based on a multicommodity flow model. In addition to wirelength optimization, the issue of reducing excessive congestion in local regions such that the router can nish the routing successfully is also considered in this thesis via a postprocessing congestion reduction technique. In general, the most accurate congestion estimation still comes from the global router itself. Optimization of power and delay in vlsi circuits using. In general, the most accurate congestion estimation still comes. In modern vlsi placement and routing tools, congestion is an important objective beyond wirelength, timing, and power.
So far, all of the congestion estimation methods perform postplacement congestion estimation. However, due to the high computational complexity, most previous works used a variety of simplified approximations to estimate the congestion. Robust temperaturebased optimization for global routing. It determines the geometric locations of the connections between elements of a circuit.
Some notso congested designs may have pockets of high congestion which will again create routing issues. Research in vlsi routing has received much attention in the literature. However, attempting to solve such problems at the physical design stage is too late, since the optimization potentials of layout tools are limited by. Bounding the efforts on congestion optimization for physical.
Multilevel global placement with congestion control. In global and detailed routing stages, it is used to generate the routing topology of each net. Estimation and optimization integrated circuits and systems by prashant saxena 2007 english pdf. Kahng, ucsd rtl design flow rtl synthesis hdl netlist logic optimization netlist library physical design layout a b s q 0 1 d clk a b s q 0 1 d clk module generators manual design courtesy k. Routability optimization has become a major concern in physical design of vlsi circuits. This paper presents a new vlsi architecture of the motion estimation in mpeg2. Some other algorithms used a routing estimation model to predict routing congestion during placement. Congestion in vlsi physical design flow vlsi basics and. Estimation and optimization provides the reader with a complete understanding of the root causes of routing congestion in presentday and future vlsi circuits, available techniques for estimating and optimizing this congestion, and a critical analysis of the accuracy and effectiveness of these techniques. This research was partially supported by the marco gi. Routing congestion analysis and reduction in deep submicron.
In this thesis, a new method is proposed to consider the temperature factor in. In order to optimize interconnect cost, we need a good congestion. From graph partitioning to timing closure chapter 6. From graph partitioning to timing closure chapter 4.
Aqil burneyb, jawed naseemc, kashif rizwand abstract space, power consumption and speed are major design issues in vlsi circuit. We present a novel global routing and crosspoint assignment methodology for seaofgates sog designs. Fast and accurate routing demand estimation for efficient. Fpga routing and routability estimation via boolean. This paper presents a stochastic closed loop congestion estimation algorithm for a placed netlist based on routers behavior. This volume provides a complete understanding of the fundamental causes of routing congestion in presentday and nextgeneration vlsi circuits, offers techniques for. A predictive distributed congestion metric with application. Traditionally, this process is partitioned into two steps. This approach improves the accuracy of congestion but the routing congestion is still not dynamically updated. A predictive distributed congestion metric and its. Introduction minimizing the total routed wire length is one of the fundamental goals in very large scale integration vlsi placement stage. Power optimization and assessment of optimization using vlsi.
Estimation and optimization is a valuable reference for cad developers and researchers, design methodology engineers, vlsi design and cad students, and vlsi design engineers. A particular focus of this work is on the congestion issues that deal primarily with standard cell based design. However, this is a very new metric and several open questions about it. Highlevel area and power estimation for vlsi circuitsy mahadevamurty nemani and farid n. Congestion prediction in early stages of physical design. Accurate pseudoconstructive wirelength and congestion. Salary 65k in silicon valley a good research opportunities. Accurate pseudoconstructive wirelength and congestion estimation. We have discussed global and detailed routing techniques. Such circuits are also the source of problems in many cad applications. Wire routing congestion dont overlook the root causes of routing congestion. Since the next generation vlsi circuits will have tens of millions modules, i fast and. Physical hierarchy generation with routing congestion control. The design component has conflicting affect on overall performance of circuits.
Due to the recent advances in vlsi technology, interconnect has become a dominant factor of the overall performance of a circuit. Index termscongestion estimation, routing congestion, placement, physical design, technology mapping, logic synthesis i. In this paper, we present a polynomial time algorithm for the global routing problem based on integer programming formulation with a theoretical approximation bound. Shelar intel corporation hillsboro, or, usa sachin s. As shown in below figure, we can set cell density to a flexible number to reduce the congestion by using the command. However, as vlsi circuits are growing in complexity and more importantly in the presence of extremely large number of ip blocks, not only the wirelength but also the congestion needs to be emphasized at the placement. As a result, there is a need for high level power estimation and optimization as well as modeling for area, timing, noise, etc. Routing congestion analysis and reduction in deep sub. It is difficult to route a highly congested design. An introduction to routing congestion springerlink. Routing congestion is a function of routing demand and routing supply, and measures the extent to which routing is feasible in each region, in the sense of taking no more.
Routing congestion in vlsi circuits estimation and optimization prashant saxena synopsys, inc. Measuring routing congestion for multilayer global routing. Estimation and optimization prashant saxena, rupesh s. In order to place routable circuits, these two steps have to be combined by estimating the routability during placement. Routing is one of the most fundamental steps in the physical design flow and is typically a very complex optimization problem. Detailed routing 4 klmh lienig timingdriven routing global routing detailed routing large singlenet routing coarsegrain assignment of routes to routing regions chap. Global routing in vlsi very large scale integration design is one of the most challenging discrete optimization problems in computational theory and practice. Results obtained show that the at congestiondriven placement approach reduces the. There are two different routing estimation approaches in the placement stage, namely empirical estimators and stochastic estimators. Accuracy and efficiency in power estimation involved in the design phase is important in order to meet power specifications without high cost redesign process. Rutenbar, fellow, ieee abstract guaranteeing or even estimating the routability of a portion of a placed.
However, this is a very new metric and several open questions about it remain unanswered. Physical design applications such as routing and partitioning work hard. Pe of an edge e between two neighboring grid cells is where. These algorithms differ mainly in the way they model routing estimation. After cts, the tool can give you a congestion map by a trial route global route values. We have developed interconnect optimization algorithms and a new. It is important that the congestion is analysed and fixed before detailed routing.
A fast congestion estimator for routing with bounded detours. Estimation and optimization library of congress control number. Index terms congestion estimation, physical design, placement, routability. In order to ac hiev e suc ha c hallengi ng ob jectiv e, a n um b er of. There are two different routing estimation approaches in the placement stage, namely empirical and stochasticbased methods. Evaluation, prediction and reduction of routing congestion.
Ece 902 simulation, modeling, and optimization for vlsi. Optimization of power and delay in vlsi circuits using transistor sizing and input ordering by chin hwee tan b. Algorithm and mathematical programming a application. Introduction as the vlsi fabrication enters the deep submicron era, the design becomes larger and more congested.
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