Clock Domain Crossing Violation Detection in Memory Design
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Solution Overview
Problem
Conventional methods for verifying clock domain crossing (CDC) in memory device designs face difficulties due to metastability issues and generate numerous noise violations, making it challenging to accurately detect valid CDC violations in asynchronous clock domains.
Innovation Solution
A computing device and method that parse a Netlist to generate a circuit database, construct a clock tree database, extract non-toggled points to create a false path database, and identify CDC violations from simulation waveforms using the clock tree and false path databases, thereby filtering out noise violations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RTL simulation or STA is used for CDC verification, then the verification process can be performed, but metastability causes transmission problems in asynchronous clock boundaries leading to inaccurate detection
Solution Approach 1:
The patent extracts and removes false CDC violation paths from the analysis results by comparing simulation waveforms against identified non-toggled points. This separation of valid violations from false positives directly addresses the metastability detection problem by filtering out inaccurate detections caused by conventional STA/RTL simulation limitations.
Solution Approach 2:
The patent introduces an intermediary verification process that uses simulation waveform analysis to mediate between the CDC tool's static analysis results and the actual circuit behavior. This intermediary step resolves the metastability issue by providing dynamic verification that accounts for actual signal transitions rather than relying solely on static timing analysis.
2Measurement precision
If CDC analysis is performed using conventional tools, then CDC violations can be identified, but numerous noise violations are generated making it difficult to distinguish valid violations
Solution Approach 1:
The patent converts the harmful effect of excessive false positive violations into a benefit by using the simulation waveform data to identify and categorize non-toggled points. These previously harmful false positives become useful information for filtering, allowing the system to distinguish valid violations from noise by comparing against the identified non-toggled patterns.
Solution Approach 2:
The patent implements a feedback mechanism where simulation waveform results are fed back into the CDC analysis process to validate and filter violations. The CDC tool's output is cross-referenced with actual simulation behavior, creating a feedback loop that eliminates false positives and improves the precision of violation identification.
3Reliability
If comprehensive CDC analysis is performed on all clock domains, then all potential violations are detected, but the analysis complexity and processing time increase significantly
Solution Approach 1:
The patent segments the CDC verification process into distinct components: initial CDC analysis, simulation waveform extraction, non-toggled point identification, and false path filtering. This segmentation allows each component to be optimized independently and reduces overall system complexity by breaking down the comprehensive analysis into manageable, modular steps.
Solution Approach 2:
The patent performs preliminary identification of non-toggled points from simulation waveforms before the final CDC violation reporting. This preliminary action filters out known non-issue points in advance, reducing the complexity of the subsequent analysis and allowing the system to maintain comprehensive verification without proportional increases in processing complexity.
Data Source
AI summary
A method of operating a computing device for detecting clock domain crossing (CDC) violation in a design of a memory device, the method includes parsing a Netlist to generate a circuit database, parsing a clock tree using the circuit database to generate a clock tree database, extracting a non-toggled point using the clock tree database to generate a false path database based on the non-toggled point, and extracting a CDC violation identified from one or more simulation waveforms using the clock tree database and the false path database.