Static Timing Analysis Margin Calibration for Integrated Circuits
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Solution Overview
Problem
Existing static timing analysis methods for integrated circuits lead to inaccurate margin estimation, resulting in either optimistic or pessimistic analysis results, which can cause yield drops or increased power consumption and area, leading to higher costs and suboptimal chip performance.
Innovation Solution
A margin calibration method and system that measures performance data from multiple dies, simulates performance, and uses statistical modeling to calculate an optimal margin, adjusting static timing analysis results to achieve accurate margin estimation, thereby improving yield and reducing resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing STA method with fab-provided margin is used, then margin estimation can be obtained, but analysis results become inaccurate leading to either optimistic or pessimistic outcomes
Solution Approach 1:
The patent implements feedback by measuring actual performance on multiple physical dies and using these measurements to iteratively adjust and calibrate the STA margin. The measured performance data feeds back into the statistical model to refine the margin estimation, creating a closed-loop system that continuously improves accuracy based on real-world observations rather than relying solely on fab-provided empirical margins.
Solution Approach 2:
The patent changes the margin parameter from a fixed fab-provided value to a dynamically calibrated value derived from actual die measurements. By treating the margin as a variable parameter that can be adjusted based on measured performance data and statistical analysis, the system transforms the margin from a static empirical rule into an adaptive parameter that reflects actual circuit behavior across multiple dies.
2Reliability
If conservative chip speed reduction is applied, then yield can be maintained, but chip performance and power consumption deteriorate
Solution Approach 1:
The patent replaces the conservative mechanical approach of reducing chip speed with a data-driven statistical calibration method. Instead of applying a uniform speed reduction to maintain yield, the system uses statistical analysis of actual die measurements to precisely calibrate the margin, enabling more accurate prediction of which chips can achieve higher speeds without sacrificing yield.
Solution Approach 2:
The patent performs preliminary calibration actions by measuring and analyzing multiple dies before final production decisions are made. This preliminary statistical analysis provides advance information about actual circuit performance characteristics, allowing for optimized speed settings that maintain yield while maximizing performance, rather than applying conservative reductions as a precaution.
3Ease of manufacture
If transistor-level margin is applied to design logic level, then margin can be obtained, but errors occur due to different analysis conditions
Solution Approach 1:
The patent transitions from a single-level transistor analysis to a multi-dimensional approach that bridges the transistor level and logic level through statistical modeling. By introducing the dimension of statistical analysis across multiple dies and multiple logic paths, the system reconciles the different analysis conditions between transistor-level fabrication data and logic-level circuit behavior, eliminating the errors that arise from direct application.
Solution Approach 2:
The patent introduces statistical analysis and empirical data from multiple dies as an intermediary between transistor-level fabrication parameters and logic-level circuit performance. This intermediary layer translates and reconciles the different analysis conditions, converting transistor-level margin provisions into accurate logic-level margin estimates by accounting for the statistical variations and interactions that occur at the circuit level.
Data Source
AI summary
A margin correction method and a margin correction system for static timing analysis are provided. The margin calibration method includes: measuring dies on a to-be-tested chip with a target circuit to obtain performance data records; obtaining simulation data records for simulating performances of the dies; executing a static timing analysis (STA) tool to obtain timing analysis results; statistically calculating a simulation process corner based on the timing analysis results; obtaining a measurement process corner based on the performance data records; establishing a statistical model that defines a margin as a difference between the measurement process corner and the simulation process corner; substituting the timing analysis results and the measurement process corner into the statistical model and execute a model fitting algorithm, for fitting the statistical model to a target model to obtain the margin; and obtaining calibrated timing analysis results.