2-pin Logic Cell Orientation Optimization via Gravity Point Attraction
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Solution Overview
Problem
Current computer-aided design tools do not optimize the orientation of 2-pin logic cells, leading to increased propagation delay and routing length in IC designs, and struggle with wire crossing and branched signal paths, which complicates the interconnection of tens to hundreds of thousands of logic cells.
Innovation Solution
The 'paths-based flip' orientation optimization method sets the output of each 2-pin logic cell as a 'gravity point' to attract the input of the next cell, allowing for optional flipping to minimize routing length and reduce wire crossings, while considering the impact on subsequent stages to avoid enlarging net bounding boxes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If standard logic cell placement is performed using timing driven strategy or wire-length driven strategy, then placement sequence is determined to reduce propagation delay or routing length, but orientation of 2-pin logic cells is not optimized leading to increased routing length and wire crossings
Solution Approach 1:
The patent applies dynamics by allowing 2-pin logic cells to be flipped between horizontal and vertical orientations during the placement process. The placement algorithm dynamically adjusts cell orientations based on signal path directions and routing requirements, transforming a static placement problem into a dynamic optimization problem that can adapt to different routing scenarios to minimize total routing length.
Solution Approach 2:
The patent changes the orientation parameter of 2-pin logic cells from fixed to variable. By introducing orientation as a configurable parameter that can take multiple values (horizontal/vertical), the system optimizes the placement by adjusting this parameter to reduce wire crossings and routing length, rather than using a fixed placement orientation.
2Ease of manufacture
If 2-pin logic cells are placed without orientation optimization, then placement process is simpler, but wire crossings occur requiring multiple metal layers and vias increasing manufacturing complexity
Solution Approach 1:
The patent applies preliminary action by determining the optimal orientation of 2-pin logic cells during the placement stage, before the routing stage. By pre-orienting cells to minimize wire crossings and routing length, the system reduces the complexity of subsequent interconnection processes, requiring fewer metal layers and vias, thus simplifying manufacturing.
3Length of moving object
If output of each 2-pin logic cell is set as gravity point to attract input of next cell, then routing length is minimized, but net bounding box may be enlarged affecting subsequent stages
Solution Approach 1:
The patent applies feedback by evaluating the impact of orientation changes on subsequent stages through net bounding box calculations. After flipping a 2-pin logic cell to optimize routing length, the system checks whether this change enlarges the net bounding box of subsequent stages. If it does, the system reverses the orientation change, using feedback from the bounding box analysis to guide the final orientation decision.
Data Source
AI summary
In an orientation optimization, at least one signal chain path starting from a signal source and passing through a series of M 2-pin logic cells is located according to a netlist. An output of the Nth 2-pin logic cell in the series of M 2-pin logic cells, where N<M, is set as a gravity point to attract an input of the (N+1)th 2-pin logic cell, thereby optionally flipping the (N+1)th 2-pin logic cell.