Variable Combination Time-Sequence Coverage for Multi-Variable Verification
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Solution Overview
Problem
Existing time sequence function coverage methods in chip verification are complex, limited to single-variable scenarios, lack necessary constraints, and cannot effectively set weights for segments, failing to meet the requirements of multi-variable verification.
Innovation Solution
A variable combination time sequence function coverage structure and random test algorithm are employed, allowing for the construction of a three-layer structure to represent relationships where multiple variables vary over time, with weights assigned to value segments, and using random seeds for reproducible excitation generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the covergroup-coverpoint-bins structure is used for time sequence function coverage, then time sequence coverage can be achieved, but the implementation becomes complex and requires large quantities of additional information
Solution Approach 1:
The patent extracts the time sequence coverage requirement from the complex covergroup-coverpoint-bins structure and implements it through a simplified variable combination time sequence function coverage structure. This structure directly represents variable relationships over time without requiring additional covergroup and coverpoint constructs, thereby reducing implementation complexity while maintaining coverage reliability.
Solution Approach 2:
The variable combination time sequence function coverage structure serves multiple functions simultaneously: it defines time sequences, combines multiple variables, sets constraints, and assigns weights all within a single unified structure. This eliminates the need for separate constructs for each function, reducing overall system complexity while achieving comprehensive coverage.
2Reliability
If the covergroup-coverpoint-bins structure is used, then single-variable time sequence coverage is possible, but multi-variable time sequence coverage cannot be supported
Solution Approach 1:
The patent merges multiple variables and their time sequences into a single unified variable combination time sequence function coverage structure. This structure allows simultaneous definition and tracking of multiple variables (e.g., a, b, c) and their value combinations across time points, enabling multi-variable coverage while maintaining the simplicity of single-variable handling.
Solution Approach 2:
The patent adds a combination dimension to the traditional single-variable time sequence approach. By introducing the variable combination aspect, the structure can represent not just individual variable changes over time but also the relationships and combinations of multiple variables simultaneously, thereby extending capability to multi-variable scenarios.
3Reliability
If the covergroup-coverpoint-bins structure is used, then time sequence definition is possible, but no corresponding constraint syntax is provided
Solution Approach 1:
The patent combines constraint definition capabilities directly into the variable combination time sequence function coverage structure. The structure itself serves as the constraint mechanism, eliminating the need for separate constraint syntax. Users can directly define time sequences, variable combinations, and constraints within the same structure, making the system easier to operate and more versatile.
4Reliability
If the covergroup-coverpoint-bins structure is used, then time sequence coverage is achievable, but weight cannot be set for segments
Solution Approach 1:
The patent introduces weight assignment capability at the segment level within the variable combination time sequence function coverage structure. Each segment can be assigned a specific weight to indicate its importance or frequency, allowing differentiated treatment of different time sequence segments. This local quality attribute enables flexible verification requirements while maintaining the overall time sequence coverage structure.
Data Source
AI summary
A test method and system based on a variable combination time sequence function coverage are provided, where the method includes: constructing a variable combination time sequence function coverage structure, and using the variable combination time sequence function coverage structure as a random constraint; determining a random seed of each value range of each variable in the variable combination time sequence function coverage structure; sequentially obtaining a time point as a current time point based on a time sequence of the variable combination time sequence function coverage structure; obtaining a value segment of each variable at the current time point from the variable combination time sequence function coverage structure, to form a variable combination structure at the current time point; and for the variable combination structure at the current time point, generating a random excitation of each variable to perform testing in a current scenario.