Approximate IC Placement via Probability Distributions

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current placement methods for integrated circuit design, such as minimum cut/partitioning, quadratic programming, force-directed, analytic, and simulated annealing, face issues with stability, speed, and quality of results, failing to provide a balance between fast and stable performance while optimizing objectives like wirelength and density.

Innovation Solution

The method employs probability distribution functions to approximate the placement of standard cells, macro-blocks, and I/O pads, gradually localizing these distributions to satisfy placement constraints and optimize objective functions, incorporating global optimization steps and refinement operations to improve runtime and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If minimum cut/partitioning based methods are used, then placement speed is improved, but stability and quality of results deteriorate

Engineering Contradiction:
Improveplacement speedVSAvoidstability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The placement process is divided into multiple refinement stages. Each stage applies different optimization strategies to progressively improve the placement solution. This segmentation allows the system to achieve both speed (through coarse initial placement) and stability (through iterative refinement), resolving the contradiction between fast placement and stable results.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary placement using fast minimum cut/partitioning methods to establish an initial solution, then applies subsequent refinement operations to improve stability and quality. This preliminary action provides a fast baseline while leaving room for iterative improvements that enhance reliability without significantly increasing total runtime.

Inventive Principle:
Principle #10Preliminary action

2Speed

If quadratic programming based methods are used, then placement speed is improved, but quality of results deteriorates

Engineering Contradiction:
Improveplacement speedVSAvoidquality of placement
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The placement optimization is segmented into multiple refinement stages that progressively improve solution quality. The system starts with fast quadratic programming-based placement and then applies additional refinement operations (such as local search, simulated annealing, or analytical methods) to progressively improve placement quality while maintaining reasonable runtime through the segmentation of the optimization process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system continuously refines the placement solution through multiple iterative improvement steps. Rather than relying on a single placement method, the system continuously applies refinement operations that build upon the initial quadratic programming solution, progressively improving quality while the overall process remains efficient due to the continuous nature of the refinement.

Inventive Principle:
Principle #20Continuity of useful action

3Manufacturing precision

If analytic placement methods are used, then quality of results is improved, but placement speed deteriorates

Engineering Contradiction:
Improvequality of placementVSAvoidplacement speed
Core Design Contradiction:
Manufacturing precisionVSSpeed

Solution Approach 1:

The system segments the placement process into a fast initial placement phase (using minimum cut or quadratic programming) followed by multiple refinement phases (using analytical methods). This segmentation allows the system to achieve high quality results through analytical methods while maintaining speed by limiting the application of computationally intensive methods to only the refinement stages rather than the entire placement process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary placement using faster methods to establish an initial solution, then applies analytical placement methods as a refinement step. This preliminary action provides a fast baseline placement that reduces the computational burden required for subsequent analytical refinement, thereby achieving high quality results without proportionally increasing total runtime.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If force-based placement methods are used, then stability is improved, but placement speed deteriorates

Engineering Contradiction:
ImprovestabilityVSAvoidplacement speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The system segments the placement process to apply force-based methods only as a refinement technique rather than the primary placement method. The initial placement uses faster minimum cut or quadratic programming methods, and then force-based refinement is applied iteratively to improve stability. This segmentation allows the system to benefit from the stability of force-based methods without suffering from their slowness, as they are applied only to refine rather than compute the entire placement.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS8572540B2Method and system for approximate placement in electronic designs
Publication Date: 2013.10.29 CADENCE DESIGN SYST INC
  • US8572540B2 patent drawing
  • US8572540B2 patent drawing
  • US8572540B2 patent drawing

AI summary

Disclosed are method, system, and computer program product for a method and system for a fast and stable placement/floorplanning method that gives consistent and good quality results. Various embodiments of the present invention provide a method and system for approximate placement of various standard cells, macro-blocks, and I/O pads for the design of integrated circuits by approximating the final shapes of the objects of interest by one or more probability distribution functions over the areas for the objects of interest with improved runtime and very good stability. These probability distributions are gradually localized to final shapes satisfying the placement constraints and optimizing an objective function.