Routing Congestion in VLSI Circuits

With dramatic increases in on-chip packing densities, routing congestion has become a major problem in integrated circuit design, impacting convergence, performance, and yield, and complicating the synthesis of critical interc- nects. The problem is especially acute as interconnects are becoming the performance bottleneck in modern integrated circuits. Even with more than 30% of white space, some of the design blocks in modern microprocessor and ASIC designs cannot be routed successfully. Moreover, this problem is likely to worsen considerably in the coming years due to design size and technology scaling. There is an inherent tradeo? between choosing a minimum delay path for interconnect nets, and the need to detour the routes to avoid “tra?c jams”; congestion management involves intelligent allocation of the available int- connect resources, up-front planning of the wire routes for even distributions, and transformations that make the physical synthesis ?ow congestion-aware. The book explores this tradeo? that lies at the heart of all congestion m- agement, in seeking to address the key question: how does one optimize the traditional design goals such as the delay or the area of a circuit, while still ensuring that the circuit remains routable? It begins by motivating the c- gestion problem, explaining why this problem is important and how it will trend. It then progresses with comprehensive discussions of the techniques available for estimating and optimizing congestion at various stages in the design ?ow.

With the dramatic increases in on-chip packing densities, routing congestion has become a major problem in chip design. The problem is especially acute as interconnects are also the performance bottleneck in integrated circuits. The solution lies in judicious resource management. This involves intelligent allocation of the available interconnect resources, up-front planning of the wire routes for even wire distributions, and transformations that make the physical synthesis flow congestion-aware.

Routing Congestion in VLSI Circuits: Estimation and Optimization provides the reader with a complete understanding of the root causes of routing congestion in present-day 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 that the reader may prudently choose an approach that is appropriate to their design goals. The scope of the work includes metrics and optimization techniques for routing congestion at various stages of the VLSI design flow, including the architectural level, the logic synthesis/technology mapping level, the placement phase, and the routing step. A particular focus of this work is on the congestion issues that deal primarily with standard cell based design.

Routing Congestion in VLSI Circuits: Estimation and Optimization is a valuable reference for CAD developers and researchers, design methodology engineers, VLSI design and CAD students, and VLSI design engineers.