Statistical Timing Analysis for Integrated Circuit Frequency Enhancement
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Solution Overview
Problem
Current integrated circuit design methods involving corner-based analysis and those considering process variation are inefficient due to lack of consideration for process variation and excessive pessimism, leading to suboptimal and time-consuming generation of cell-related information.
Innovation Solution
A system and method for analyzing timing paths in integrated circuit design that uses a design management component to identify and modify critical paths, generating a modified design that improves performance by considering all paths and applying probability theory to enhance timing optimization, including static timing analysis and probability density function analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If corner-based analysis through static timing is used, then the method is simple to implement, but it does not take process variation into account leading to inaccurate timing analysis
Solution Approach 1:
The patent transforms the timing analysis from deterministic corner-based parameters to statistical parameters by generating probability density functions for timing paths. This allows the analysis to capture process variation through statistical distributions rather than fixed corner values, improving accuracy while maintaining computational feasibility through efficient sampling methods.
Solution Approach 2:
The patent replaces the traditional mechanical corner-based analysis system with a statistical probability-based system. Instead of analyzing fixed worst-case corners, the system uses probability density functions and statistical sampling to model timing behavior under process variation, substituting deterministic mechanics with statistical mechanics.
2Measurement precision
If statistical properties of underlying cells are considered, then process variation is taken into account, but undue amounts of pessimism are employed with regard to the circuit design
Solution Approach 1:
The patent applies partial action by analyzing only the necessary subset of timing paths that contribute significantly to the overall timing distribution. Instead of excessively analyzing all possible paths with full statistical rigor, the system samples representative paths and uses their probability density functions to characterize the entire design, reducing pessimism while maintaining accuracy.
Solution Approach 2:
The patent introduces dynamics by using probability density functions that can adapt and evolve based on the specific characteristics of each timing path. Rather than applying static pessimistic margins uniformly across all paths, the system dynamically adjusts the statistical analysis to reflect actual process variation impacts on each path, reducing unnecessary conservatism.
3Measurement precision
If statistical properties of underlying cells are considered, then process variation is taken into account, but an undesirable amount of time is used to generate cell-related information
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing probability density function characteristics for standard cell libraries during the library generation phase. This preliminary statistical characterization of cells allows the timing analysis tool to efficiently query and combine pre-computed statistical data rather than generating cell statistics on-demand during actual timing analysis, significantly reducing analysis time.
Solution Approach 2:
The patent segments the timing analysis into independent timing path segments, each with its own probability density function. By breaking down the overall timing analysis into separable path segments that can be analyzed and combined independently, the system avoids the computational expense of analyzing the entire design as a single statistical entity, reducing overall analysis time while maintaining accuracy.
4Productivity
If corner-based analysis analyzes only the worst mean value, then the analysis is fast, but it does not provide comprehensive timing path optimization
Solution Approach 1:
The patent applies partial action by selectively analyzing timing paths based on their contribution to the overall timing distribution. Instead of exhaustively analyzing all paths with equal depth, the system identifies and focuses computational resources on the critical subset of paths that most significantly impact the timing distribution, achieving comprehensive optimization coverage with reduced computational effort.
Solution Approach 2:
The patent changes the analysis parameter from single worst-case mean values to full probability density function distributions. This parameter transformation allows the system to capture the complete timing behavior including variations and correlations, providing comprehensive timing path optimization coverage while using efficient sampling and statistical methods to maintain analysis speed.
Data Source
AI summary
Techniques efficiently improve an integrated circuit design by simultaneously analyzing timing paths of the circuit design. A design management component can access data relating to the integrated circuit design from a design database. The design management component can perform a static timing analysis of the integrated circuit design and generate a timing path distribution, filtered analytics, and/or a probability density function associated with the integrated circuit design, wherein all of the timing paths of the integrated circuit design can be evaluated. The design management component can determine a modification to make to a cell, device, interconnection between cells or devices, or another element(s) of the integrated circuit design, based at least in part on the static timing analysis, the timing path distribution, the filtered analytics, and/or the probability density function, to generate a modified integrated circuit design, in accordance with defined design criteria.