Zigzag Detection and Rerouting in IC Net Routing
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Solution Overview
Problem
Conventional approaches to zigzag detection in integrated circuit (IC) design often fail to accurately identify zigzags, especially in long connection paths, leading to degraded circuit performance due to high resistance via connections.
Innovation Solution
An improved method for zigzag detection and handling in IC design, which involves setting a minimum turn threshold and a turn density constraint to identify zigzagging portions of connection paths, and subsequently rerouting the nets to remove these zigzags using a routing engine with specific turn constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional zigzag detection methods are used, then the detection process is simple, but the accuracy of zigzag detection is low especially in long connection paths
Solution Approach 1:
The connection path is divided into multiple segments based on the minimum turn threshold. Each segment is independently evaluated for zigzag characteristics by counting turns and calculating turn density. This segmentation allows accurate detection of local zigzag patterns even in long connection paths without requiring complex global analysis.
Solution Approach 2:
The detection method applies different evaluation criteria to different segments of the connection path. Each segment is assessed based on its local turn density rather than applying a single global threshold. This local quality approach enables accurate identification of zigzag portions while maintaining simplicity in the overall detection process.
2Reliability
If zigzags are not removed, then the routing is simple, but the circuit performance degrades due to high resistance via connections
Solution Approach 1:
The zigzag detection and identification is performed during the routing process before finalization. By detecting zigzag portions early and applying turn constraints to the routing engine, the system prevents performance-degrading zigzags from being created in the first place, rather than requiring complex post-routing modifications.
Solution Approach 2:
The routing engine is provided with specific turn constraints as parameters based on the detected zigzag portions. By changing the routing parameters to limit turns in identified zigzag segments, the system effectively removes harmful zigzags while maintaining routing simplicity through parameter-based control rather than complex geometric modifications.
Data Source
AI summary
Aspects of the present disclosure address systems and methods for zigzag detection and handling for integrated circuit designs. Data describing an integrated circuit is accessed. The integrated circuit design comprises a connection path between two or more pins of a net determined based on an initial routing of the net. A zigzag is detected in the connection path based on a local turn density constraint that specifies a ratio of a number of turns to a pathlength that corresponds to zigzagging in the net. In response to detecting the zigzag in the connection path, the zigzag is removed from the connection path by rerouting the net using a routing constraint that defines a maximum number of turns in the connection path.