Scan Chain Reconstruction via Bidirectional Preference Selection
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Solution Overview
Problem
Existing structural optimizations for scan chains in chip physical design focus on single indices, such as time optimization, and neglect global considerations, leading to inefficient use of wiring resources and potential wiring congestion.
Innovation Solution
A method and device for reconstructing scan chains using two-way preference selection, where first and second preference sequences are established based on distances to starting and ending points, and between scan chains, allowing for redistribution of scanning elements to optimize wiring usage while maintaining testing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scan chains are inserted during logic design without physical information, then testing capability is ensured, but wiring resources are excessively consumed causing congestion
Solution Approach 1:
The patent performs preliminary optimization of scan chain structure during the physical design phase by calculating optimal starting and ending positions based on physical layout information. This preliminary action redistributes scanning elements to minimize wiring resource consumption while maintaining testing capability, preventing wiring congestion before it occurs.
Solution Approach 2:
The patent changes the structural parameters of scan chains by optimizing the selection of starting and ending positions of scanning elements. By adjusting these parameters based on physical design information, the patent reduces wiring resource consumption while preserving the essential testing function.
2Productivity
If existing optimizations focus only on single indices such as time optimization, then specific performance metric is improved, but global wiring efficiency deteriorates
Solution Approach 1:
The patent creates a multi-objective optimization approach that simultaneously considers both testing efficiency (time index) and wiring resource consumption (physical resource index). The optimization model integrates multiple objectives to achieve global optimization of scan chain structure, rather than optimizing single indices in isolation.
Solution Approach 2:
The patent adds a new dimension to scan chain optimization by incorporating physical layout information and spatial relationships into the optimization process. This transforms the optimization from a one-dimensional time-based metric to a multi-dimensional problem that includes spatial wiring resource consumption.
3Device complexity
If existing optimizations consider only lengthwise or horizontal position of scanning elements, then partial optimization is achieved, but starting and end positions are neglected
Solution Approach 1:
The patent segments the scan chain structure into distinct components including starting positions, ending positions, and intermediate scanning elements. By separately optimizing each segment's position and configuration, the patent achieves comprehensive structural optimization that reduces overall wiring resource consumption.
Solution Approach 2:
The patent applies different optimization strategies to different parts of the scan chain structure. Starting and ending positions receive specialized optimization attention with different criteria than intermediate elements, allowing each part to be optimized according to its specific characteristics and impact on wiring resources.
Data Source
AI summary
Provided are methods and devices of organizing scan chains in an integrated circuit. One method comprises generating first preference information representing prioritized listing of a plurality of scanning elements for each of a plurality of scan chains based on a first criterion, generating second preference information representing prioritized listing of the plurality of scan chains for each of the plurality of scanning elements based on a second criterion and at a computing device, assigning each of the plurality of the scanning elements to one of the plurality of the scan chains based on the first preference information and the second preference information.