C-Routing Hard Soft Rule Balancing Cost Analysis
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Solution Overview
Problem
Conventional design techniques struggle to effectively manage both hard and soft rules during the detail routing process in integrated circuit design, making it difficult to balance compliance with mandatory hard rules and preferred soft rules, especially at the detail router level.
Innovation Solution
The approach involves performing C-routing, which simultaneously considers and balances hard and soft rules by using a cost-based method to determine optimal track assignments across global cells, allowing for concurrent management of both rule types during the C-routing process, thereby reducing the complexity of managing these rules during detail routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional detail routing techniques are used to manage hard and soft rules, then routing can be performed, but the complexity of managing both rule types simultaneously becomes unmanageable
Solution Approach 1:
The patent segments the routing process into three distinct levels: global routing, C-routing, and detail routing. Hard rules are managed at the global and C-routing levels, while soft rules are primarily managed at the detail routing level. This segmentation allows each routing level to focus on specific rule types, making the overall system manageable and effective.
Solution Approach 2:
C-routing acts as an intermediary layer between global routing and detail routing. It serves as a transition zone where hard rules are enforced and where the path is established before detail routing occurs. This intermediary function allows soft rules to be applied during detail routing without the complexity of managing both rule types simultaneously at the detail level.
2Reliability
If the Lee algorithm is used for routing, then a route can be found if one exists, but the process becomes slow and memory intensive
Solution Approach 1:
The patent divides the routing process into three levels: global routing for high-level path determination, C-routing for coordinating routes across global cell boundaries, and detail routing for final wire placement. This segmentation allows each level to use appropriate algorithms optimized for its specific tasks, avoiding the need to use the slow and memory-intensive Lee algorithm throughout the entire routing process.
Solution Approach 2:
Global routing performs preliminary actions by determining the rough route for each net and establishing the overall routing framework before detail routing occurs. This preliminary path determination reduces the complexity of subsequent detail routing tasks, enabling faster and more efficient routing without requiring exhaustive search algorithms like Lee's algorithm at every stage.
3Productivity
If global routing is used to determine approximate routes, then routing speed improves, but the complexity of coordinating routes across multiple global cells increases
Solution Approach 1:
The patent introduces C-routing as an intermediate level between global routing and detail routing. C-routing specifically handles the coordination of routes that cross global cell boundaries, establishing the major part or trunk of routes between global cells. This segmentation isolates the coordination complexity to a dedicated C-routing level, allowing global routing to maintain its speed advantages while C-routing manages the coordination complexity systematically.
Data Source
AI summary
An improved approach for implementing C-routing is described. Cost-based analysis is performed to balance the different rule requirements, to optimize the assignment of objects and nets during C-routing.