Selective Fanout Optimization for IC Timing Closure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Modern integrated circuit (IC) designs face challenges in meeting aggressive timing requirements due to difficulties in determining which signal paths to optimize, leading to non-convergence conditions during the design flow, as conventional solutions focus on high fanout nets to the exclusion of other critical nets.
Innovation Solution
A method and system for improving timing by selectively reducing fanout of nets with a high number of loads or criticality at various stages of the design flow, including synthesis, placement, and routing, using processor-driven fanout optimization techniques that adapt to changing net importance and accuracy of timing models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fanout reduction is applied to all nets with high load counts, then timing performance improves, but device complexity increases and non-convergence conditions occur
Solution Approach 1:
The patent applies fanout reduction selectively to specific nets based on their criticality and load characteristics rather than uniformly to all high-load nets. The system identifies nets exceeding a threshold number of loads and applies optimization only to those with selected netlist connectivity patterns, thereby improving timing performance while avoiding the complexity and convergence issues associated with blanket fanout reduction across the entire circuit.
2Manufacturing precision
If fanout optimization is performed at multiple design flow stages, then timing closure is achieved, but processing time increases
Solution Approach 1:
The patent performs fanout optimization at multiple stages of the design flow (synthesis, placement, and routing) to progressively improve timing. By applying optimization early at synthesis stage with netlist connectivity selection, and then refining at placement and routing stages with updated timing models, the system achieves timing closure while managing processing time through staged rather than simultaneous optimization.
Solution Approach 2:
The system dynamically adapts the fanout optimization strategy based on the current design flow stage and available timing information. At synthesis stage, optimization relies on netlist connectivity patterns; at placement and routing stages, it incorporates updated timing models and criticality assessments, allowing the optimization approach to evolve as more accurate timing data becomes available.
3Manufacturing precision
If conventional fanout reduction methods are used, then some timing paths improve, but non-convergence conditions prevent timing closure
Solution Approach 1:
The patent introduces a selection mechanism based on netlist connectivity patterns to identify which high-load nets should undergo fanout reduction. By analyzing the connectivity structure and selecting only certain nets for optimization rather than applying reduction uniformly, the system improves specific timing paths while avoiding the non-convergence conditions that arise from aggressive or inappropriate fanout reduction on other nets.
Data Source
AI summary
A method of circuit design may include synthesizing a circuit design using a processor and, for the synthesized circuit design, selectively reducing, using the processor, fanout of nets having a number of loads exceeding a first threshold number of loads and having a selected netlist connectivity. The method may include placing the circuit design using a processor and, for the placed circuit design, selectively reducing, using the processor, fanout of nets according to at least one of a number of loads or criticality.