Incremental Placement Perturbation Prediction

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Solution Overview

Problem

Existing integrated circuit design methods face challenges in predicting and minimizing perturbation during incremental placement, leading to inferior quality of placement results and inefficiencies due to limitations in conventional flow-based techniques, simulated annealing, exhaustive search, diffusion-based placement, and clumping algorithms.

Innovation Solution

A method and system that predicts and minimizes perturbation by identifying initial placements, computing abstract flow, determining target locations, and using augmented clumping techniques and grid morphing to achieve legal placements with minimal disturbance, employing network flow and fluid propagation models for efficient component migration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional flow-based legalization techniques are used, then placement legalization is achieved, but perturbation prediction capability is lacking leading to inferior quality of placement results

Engineering Contradiction:
Improveplacement qualityVSAvoidperturbation prediction capability
Core Design Contradiction:
Manufacturing precisionVSLoss of information

Solution Approach 1:

The patent performs perturbation prediction before executing the actual placement legalization. By computing abstract flow and predicting cell movements in advance, the system can anticipate the impact of legalization operations and make informed decisions to minimize perturbation, rather than reacting after damage is done.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where perturbation predictions are used to guide subsequent placement adjustments. The system continuously monitors predicted perturbation and adjusts legalization strategies accordingly, creating a closed-loop control system that optimizes placement quality iteratively.

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If simulated annealing, exhaustive search, or diffusion-based placement techniques are used, then placement legalization is achieved, but computational efficiency is poor requiring more computer cycles

Engineering Contradiction:
Improveplacement legalization qualityVSAvoidcomputational efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent divides the placement legalization problem into discrete cell-level operations and uses abstract flow computation to handle each cell independently rather than performing exhaustive global optimization. This segmentation enables linear-time complexity operations while maintaining legalization quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the computational parameters from complex diffusion-based continuous optimization to discrete abstract flow computations with simplified movement predictions. This parameter transformation reduces computational complexity from exponential/diffusion-scale to linear time complexity while preserving essential legalization functionality.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If network flow or greedy techniques are used, then computational efficiency is improved, but perturbation reduction opportunities are missed due to arbitrary decisions

Engineering Contradiction:
Improvecomputational efficiencyVSAvoidperturbation reduction capability
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent incorporates perturbation prediction feedback into the network flow computation. Rather than making arbitrary greedy decisions, the system uses predicted perturbation values to guide flow assignments, ensuring that each computational decision is informed by its expected impact on placement quality.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces traditional mechanical optimization approaches (exhaustive search, simulated annealing) with an abstract flow-based computational model. This substitution enables efficient computation while incorporating perturbation awareness through the fluid propagation model that predicts cell movements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If incremental placement is performed with significant perturbation, then timing problems are corrected, but additional timing problems are introduced and convergence is hindered

Engineering Contradiction:
Improvetiming correction capabilityVSAvoidplacement stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses perturbation prediction as feedback to control the magnitude and direction of placement adjustments. By monitoring predicted perturbation levels, the system can adjust legalization strategies to correct timing issues while maintaining placement stability, preventing oscillations that would hinder convergence.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary perturbation analysis before executing placement corrections. This advance prediction allows the system to plan corrections that address timing problems while anticipating and avoiding the introduction of new timing issues, ensuring stable convergence toward the optimal solution.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS8028263B2Method, system, and computer program product for implementing incremental placement in electronics design
Publication Date: 2011.09.27 CADENCE DESIGN SYST INC
  • US8028263B2 patent drawing
  • US8028263B2 patent drawing
  • US8028263B2 patent drawing

AI summary

Disclosed are a method, system, and computer program product for implementing incremental placement for an electronic design while predicting and minimizing a perturbation impact arising from incremental placement of electronic components. In some embodiments, an initial placement of an electronic design is identified, an abstract flow is computed, target locations of various electronic components to be placed are identified, a relative ordering of electronic components is determined, and the placement is then legalized. Furthermore, in various embodiments, the method, system, or computer program product starts with an initial placement of an electronic design and derives a legal placement by using an incremental placement technique while minimizing the perturbation impact or an total quadratic movement of instances. In some embodiments, an augmented or incremental clumping technique based data structure is utilized for rapid and substantially exact perturbation prediction of effects of local incremental placement operations.