Layer Assignment for IC Timing and Area Optimization
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Solution Overview
Problem
Conventional layer assignment in integrated circuit design primarily focuses on satisfying maximum transition constraints, leading to inefficient use of middle and top routing layers and unnecessary area and power consumption, as non-timing critical nets are ignored during global timing optimization.
Innovation Solution
The introduction of a minimum-area layer assignment technique that promotes layer assignment on nets if it results in timing improvements, allowing for more efficient use of routing resources and reducing the need for additional buffers and inverters, especially in non-critical paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional layer assignment focuses on satisfying maximum transition constraints, then transition constraints are met, but routing resource utilization is inefficient and area consumption increases
Solution Approach 1:
The patent changes the optimization parameter from solely satisfying transition constraints to simultaneously optimizing timing metrics and area utilization. By introducing timing-driven layer assignment that considers critical path delays, the system reallocates routing resources to achieve both constraint satisfaction and area efficiency.
Solution Approach 2:
The patent applies different layer assignment strategies to different regions of the circuit based on timing criticality. Critical paths receive prioritized layer assignment with lower resistance characteristics, while non-critical paths use standard assignment, thereby optimizing area consumption without compromising essential timing requirements.
2Area of stationary object
If conventional layer assignment ignores timing optimization, then area consumption is reduced, but timing performance deteriorates
Solution Approach 1:
The patent performs preliminary timing analysis and identifies critical paths before layer assignment. By pre-characterizing timing requirements and incorporating them into the layer assignment algorithm, the system ensures that timing-critical nets are assigned to optimal layers before routing is finalized, preventing timing degradation.
Solution Approach 2:
The patent implements a feedback mechanism where timing analysis results from previous design stages inform the layer assignment decisions. The timing metrics calculated from netlists and placement data feed back into the layer assignment algorithm, creating a closed-loop optimization that simultaneously considers area and timing performance.
3Loss of time
If more buffers and inverters are added to improve timing, then timing performance improves, but power consumption and area increase
Solution Approach 1:
The patent replaces the mechanical approach of adding buffers and inverters with an electrical optimization approach using layer assignment. By strategically assigning nets to layers with lower resistance and capacitance characteristics, the system achieves timing improvement through electrical parameter optimization rather than adding more active devices, thereby reducing power consumption.
Data Source
AI summary
Aspects of the present disclosure address improved systems and methods for layer assignment to improve timing in integrated circuit (IC) designs. An initial placement layout of a net of an IC design is accessed. A plurality of buffer insertion candidates is generated using multiple candidate buffer insertion points and multiple layer assignments from among multiple layers of the IC design. Timing characteristics of each buffer insertion candidate are determined, and timing improvements provided by each buffer insertion candidate are determined based on respective timing characteristics. A buffer insertion candidate is selected from the plurality of buffer insertion candidates based on the timing improvement provided by the buffer insertion candidate. A layout instance for the IC is generated based in part on the selected buffer insertion candidate.