Circuit Layout Migration via Symmetry Constraint Reduction
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Solution Overview
Problem
Existing methods for analog circuit layout migration often over-constrain the compaction problem, leading to long runtimes or failure to find a solution, especially when transitioning from one manufacturing technology to another, such as from 55 nm to 40 nm CMOS technology, due to the high number of components and reliance on user expertise.
Innovation Solution
The method involves detecting regularity and symmetry features in the circuit layout by forming alignment groups and determining symmetry axes, which are then used to construct a constraint graph for compaction, reducing the number of symmetry constraints and avoiding over-constraining, allowing for efficient migration without linear programming algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing methods for analog circuit layout migration are used, then layout constraints are preserved, but the number of constraints becomes excessively large leading to long runtimes or failure to find a solution
Solution Approach 1:
The patent extracts and identifies only the essential symmetry constraints from the full set of layout constraints by detecting symmetry elements in the source layout. This selective extraction removes redundant constraints while preserving the critical ones needed for correct layout migration, thereby reducing the constraint set size and computation time.
Solution Approach 2:
The patent segments the constraint detection process into distinct phases: first detecting alignment groups of components, then identifying symmetry axes and symmetry groups based on these alignments. This segmentation allows the method to systematically reduce constraints by processing layout features hierarchically rather than treating all constraints uniformly.
2Extent of automation
If automatic layout migration procedures are used, then design expertise requirement is reduced, but the methods over-constrain the compaction problem
Solution Approach 1:
The patent implements self-service by enabling the migration tool to automatically detect symmetry constraints directly from the source layout without requiring user input. The system autonomously identifies alignment groups, symmetry axes, and symmetry groups, and automatically constructs the reduced constraint set, making the process truly automatic while avoiding over-constraining.
Solution Approach 2:
The patent changes the parameter representation from individual component constraints to grouped symmetry constraints. By transforming the constraint system from component-level to group-level parameters, the method reduces complexity while maintaining automation, as the symmetry groups capture multiple component relationships in a single constraint parameter.
3Stability of the object's composition
If all symmetry constraints are applied in layout migration, then layout regularity is preserved, but the compaction problem becomes over-constrained
Solution Approach 1:
The patent applies asymmetry by treating symmetric and asymmetric components differently in the constraint system. Only components that form symmetry groups are subjected to symmetry constraints, while asymmetric components are handled without such constraints. This selective application preserves layout regularity where it exists while avoiding the over-constraining that would result from uniformly applying symmetry constraints to all components.
Solution Approach 2:
The patent implements partial action by applying symmetry constraints only to the extent necessary - specifically to components that belong to identified symmetry groups. Rather than applying constraints to all components (excessive action), the method selectively applies constraints only where symmetry exists, thereby preserving layout regularity without over-constraining the compaction problem.
Data Source
AI summary
A method for circuit layout migration comprises creating a list of layout components in a source layout; determining a plurality of first groups of layout components being regularly aligned horizontally or vertically; determining first subsets of layout components which each belong to at least two of a respective set of determined first groups; determining a plurality of second groups of layout components, each second group comprising mutually exclusive ones of the first subsets of layout components; determining symmetry axes for pairs of second groups; building a constraint graph of the layout components of the source layout using alignment constraints for the alignment of layout components within each of the second groups and distance constraints for preserving a regularity pattern within each of the second groups and symmetry constraints for the determined symmetry axes for pairs of second groups; and performing constraint-graph-based compaction of the source layout.