Crosstalk-Aware Hierarchical Timing Model for IC Design
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Solution Overview
Problem
Hierarchical static timing analysis in integrated circuits faces challenges in accurately establishing timing budgets for functional blocks and managing lower-level block constraints within top-level designs, leading to uncertainty and inefficiency in crosstalk noise and delay error evaluation, particularly as designs grow larger.
Innovation Solution
A crosstalk-aware hierarchical timing model that performs block-level analysis, categorizes aggressors, and stores iteration-specific data to ensure consistent results, allowing for more accurate and efficient static timing analysis by replacing full gate-level netlists with block timing models, thereby reducing runtime and memory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hierarchical design flow is used with block timing models, then runtime and memory requirements are reduced, but accuracy and consistency of static timing analysis results deteriorate due to difficulty in establishing timing budgets and managing constraints
Solution Approach 1:
The patent segments the timing analysis process into block-level analysis and top-level analysis phases. Block-level analysis performs detailed STA on individual functional blocks to generate accurate timing budgets, while top-level analysis uses these budgets for system-level evaluation. This segmentation allows hierarchical design to maintain accuracy by ensuring each block's timing characteristics are precisely characterized before integration.
Solution Approach 2:
The patent implements feedback mechanisms where block-level analysis results feed into top-level analysis, and iteration-specific data from top-level analysis is used to refine block-level models. This feedback loop ensures that timing budgets and constraints are continuously refined and consistent across different hierarchical levels, resolving the accuracy issue while maintaining the efficiency benefits of hierarchical design.
2Measurement precision
If full gate-level netlists are used for static timing analysis, then accuracy of timing results is improved, but runtime extends into several days and expensive computer systems with very large memory sizes are required
Solution Approach 1:
The patent extracts timing characteristics from detailed gate-level netlists at the block level, creating condensed timing budgets that capture essential timing behavior without retaining full netlist complexity. This extraction process removes unnecessary detail while preserving critical timing information, enabling efficient top-level analysis without requiring full gate-level detail throughout the entire design hierarchy.
Solution Approach 2:
The patent transitions from a single-dimensional full netlist approach to a multi-dimensional hierarchical approach, where timing analysis occurs at multiple levels of abstraction. Block-level analysis operates at detailed gate level for accuracy, while top-level analysis operates at a higher abstraction level for efficiency. This dimensional change allows the system to achieve both accuracy and efficiency by operating at appropriate levels of detail for each analysis phase.
3Device complexity
If hierarchical design flow is used, then device complexity is reduced through modular blocks, but difficulty in managing and merging timing constraints between lower-level and top-level blocks increases
Solution Approach 1:
The patent creates universal timing budget structures that can be used across different hierarchical levels and block types. These standardized timing budgets serve multiple functions: they characterize block timing behavior for internal verification, provide constraints for top-level analysis, and enable consistent merging of constraints across hierarchy levels. This universality simplifies constraint management by providing a common framework that works at all levels of the hierarchical design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides high accuracy and consistency in static timing analysis results, significantly reducing runtime and memory needs, enhancing confidence in chip design without requiring expensive computer systems, and preserving information for block integration.
Implementation Method 1
Crosstalk is caused by capacitive coupling from one part of a circuit to another, causing noise or delay error
Implementation Method 2
Crosstalk is caused by capacitive coupling from one part of a circuit to another, causing noise or delay error. When evaluating the effect of crosstalk, the circuit which is being evaluated is referred to as the 'victim' while the circuits whose effects on the 'victim' are measured are referred to as 'aggressors'
Data Source
AI summary
A method and apparatus to provide a hierarchical timing model with crosstalk consideration is provided. In one embodiment, the method comprises performing block level analysis of a circuit, in one or a plurality of iterations, and storing per iteration data. The method further comprises, in one embodiment, utilizing the per iteration data in performing top level analysis of the circuit.