Diagonal Cut Graph Placement for IC Layout Optimization
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Solution Overview
Problem
Existing integrated circuit (IC) design placement techniques do not consider diagonal wiring, leading to inefficient layout area consumption, excessive wire usage, and poor wire congestion.
Innovation Solution
A method that computes a placement metric for IC layouts by partitioning regions using a cut graph approximation of a diagonal cut line, generating congestion-cost estimates by measuring the number of nets cut by the cut graph, and utilizing staircase cut graphs or cut arcs to emulate diagonal cut lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Manhattan wiring model with 90 degree turns is used, then wiring direction is constrained and routing is simplified, but layout area consumption increases and wire length increases
Solution Approach 1:
The patent introduces diagonal wiring directions (45 degrees) as a new dimension beyond the traditional horizontal and vertical Manhattan wiring. This allows wires to traverse the layout more directly, reducing both wire length and the area required for routing, while maintaining manufacturability through controlled diagonal segments.
2Area of stationary object
If diagonal wiring is allowed, then layout area usage is optimized and wire length is reduced, but placement complexity increases
Solution Approach 1:
The patent segments the wiring model into distinct types: horizontal segments, vertical segments, and diagonal segments. Each segment type has specific routing rules and constraints. This segmentation allows the placement algorithm to handle diagonal wiring systematically by treating it as a combination of controlled segment types rather than arbitrary complex paths.
3Ease of operation
If conventional placement techniques without diagonal consideration are used, then placement process is simpler, but wire congestion increases and placement quality deteriorates
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and pre-planning diagonal wire routes during the placement phase. Instead of adding diagonal routing as a post-processing step, the placement algorithm anticipates diagonal wiring needs and positions components accordingly, preventing wire congestion before it occurs and improving overall placement quality.
Data Source
AI summary
Some embodiments of the invention provide a method for placing circuit modules in an integrated circuit (“IC”) layout. The method computes a placement metric for the IC layout. In some embodiments, computing the placement metric includes partitioning a region of the IC layout into several sub-regions by using a cut graph, where the cut graph is an approximation of a diagonal cut line. These embodiments then generate congestion-cost estimates by measuring the number of nets cut by the cut graph. In some embodiments, the cut graph is a staircase cut graph. These staircase cut graphs include several horizontal and vertical cut lines. In some embodiments, the cut graph is a cut arc.