Statistical Timing Analysis for IC Corner Coverage
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Solution Overview
Problem
Traditional timing methodologies for integrated circuits require numerous discrete runs to account for process and environmental variations, leading to unmanageable complexity and inefficiency in achieving timing closure across the full parameter space.
Innovation Solution
A method that performs statistical timing analysis across the full parameter space, selects a subset of critical corners, projects timing results to deterministic values, and determines worst slacks to achieve timing closure on a subset of the parameter space, reducing pessimism and runtime complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple discrete timing runs are performed to cover all corners and parameter variations, then timing coverage and accuracy are improved, but the number of analysis runs becomes unmanageable and computational complexity increases
Solution Approach 1:
The patent merges multiple discrete timing runs into a single statistical timing analysis that simultaneously evaluates all corners and parameter variations. By combining the evaluation of numerous corners into one unified statistical framework, the system achieves comprehensive timing coverage without requiring separate discrete runs for each corner, thereby reducing computational complexity while maintaining reliability.
Solution Approach 2:
The patent changes the approach from fixed discrete parameter values to statistical parameter distributions. Instead of analyzing specific corner points, the system uses statistical methods to model and analyze the full distribution of parameters across all corners, transforming the problem from evaluating numerous discrete points to analyzing continuous probability spaces, thus reducing the number of required analysis runs.
2Measurement precision
If statistical timing analysis is performed across the full parameter space, then timing accuracy and coverage are improved, but runtime and computational resources increase
Solution Approach 1:
The patent applies partial action by focusing statistical timing analysis on the most critical corners and parameter variations rather than uniformly analyzing all possible combinations. By identifying and prioritizing the most impactful corners based on timing sensitivity and slack margins, the system achieves sufficient timing accuracy without exhaustively analyzing every corner, thereby reducing runtime while maintaining measurement precision.
3Productivity
If timing closure is achieved on a subset of corners, then runtime and computational efficiency are improved, but timing coverage and reliability may be compromised
Solution Approach 1:
The patent applies local quality by tailoring the statistical timing analysis to focus on specific corners and parameter combinations that have the most impact on timing closure. Instead of uniformly applying the same analysis depth to all corners, the system dynamically adjusts the analysis focus based on local timing characteristics, slack margins, and corner criticality, achieving efficient computational performance while maintaining adequate timing coverage for the most important scenarios.
Data Source
AI summary
An approach for covering multiple selective timing corners in a single statistical timing run is described. In one embodiment, a single statistical timing analysis is run on the full parameter space that covers unlimited process parameters/environment conditions. Results from the statistical timing analysis are projected for selected corners. Timing closure is performed on the corners having the worst slacks.