Variable Track Groups for IC NDR Timing Accuracy
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Solution Overview
Problem
NDR routing in integrated circuits (ICs) complicates design rule checking and introduces a gap between pre-routing and post-routing timing estimates due to increased difficulty in maintaining design rules and estimating timing benefits.
Innovation Solution
A variable track based NDR routing system that uses pre-defined tracks with different pitches, widths, and spacings to assign and optimize NDR constraints, allowing for successful routing of nets with NDR constraints and simplifying design rule checking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NDR routing is used to change resistance and capacitance of interconnect conductors, then timing benefits can be achieved, but design rule checking becomes more complicated and the gap between pre-routing and post-routing timing estimates increases
Solution Approach 1:
The routing process is segmented into multiple passes: a first routing pass that routes non-critical nets using standard rules, and a second routing pass that routes timing-critical nets using NDR rules. This segmentation allows design rule checking to be performed separately for each pass, simplifying the overall process while maintaining timing accuracy for critical nets.
Solution Approach 2:
The patent performs preliminary routing of non-critical nets before routing timing-critical nets. By completing the routing of non-critical nets first and performing design rule checking on them, the system establishes a foundation that simplifies subsequent routing of critical nets with NDR constraints, reducing the complexity of design rule checking in the second pass.
2Reliability
If NDR routing is used to optimize timing critical nets, then timing performance improves, but the gap between pre-routing and post-routing timing estimates increases
Solution Approach 1:
The patent segments the routing process to handle timing-critical nets in a dedicated second pass after non-critical nets are routed. This allows for more accurate timing estimation specific to critical nets, as the routing resources and constraints are clearly defined, reducing the gap between pre-routing and post-routing timing estimates while maintaining timing performance.
Solution Approach 2:
The system uses feedback from the identification of timing-critical nets to adjust routing strategies. By analyzing which nets are timing-critical and routing them with specific NDR constraints in the second pass, the system refines timing estimates based on actual routing outcomes, reducing the discrepancy between pre-routing and post-routing timing predictions.
3Ease of manufacture
If standard routing rules are used for all nets, then routing simplicity is maintained, but timing critical nets cannot achieve optimal performance
Solution Approach 1:
The patent applies different routing rules to different subsets of nets based on their timing characteristics. Standard routing rules are applied to non-critical nets where simplicity is sufficient, while NDR routing rules are applied locally to timing-critical nets that require optimized performance. This local differentiation maintains overall routing simplicity while achieving optimal timing performance where needed.
Solution Approach 2:
The routing process is divided into two distinct passes: the first pass uses standard routing rules for non-critical nets, maintaining simplicity, while the second pass uses NDR routing rules for timing-critical nets, optimizing performance. This segmentation allows each subset of nets to receive the appropriate level of routing complexity.
Data Source
AI summary
A device including first track groups on a first conductive layer of an integrated circuit. Each of the first track groups including at least one of a different first track group pitch, a different first track group spacing, and a different first track group width than the other first track groups. Where each of the first track groups includes first tracks that have at least one of a different first track width and a different first track spacing than the first tracks in the other first track groups.