Clock Mesh Skew Control Using Optimal Coarse Delay Setting
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Solution Overview
Problem
Existing integrated circuits face challenges in effectively synchronizing clock skew between clock meshes, leading to operational failures, necessitating improved methods for adjusting skew to ensure efficient and correct chip operation.
Innovation Solution
A method involving iterative measurement of clock skew between two clock meshes, applying programmable delays, including coarse and fine delay steps, to identify an optimal coarse delay setting, which is maintained during functional operation, with fine delay adjustments applied to synchronize the clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only fine delay steps are used to adjust clock skew, then measurement precision is improved, but device complexity and adjustment time increase
Solution Approach 1:
The delay adjustment mechanism is segmented into two distinct components: coarse delay steps for large-range adjustments and fine delay steps for precise tuning. This segmentation allows the system to achieve high measurement precision while keeping the overall device complexity manageable by dividing the adjustment task into hierarchical levels.
Solution Approach 2:
The system dynamically switches between coarse and fine delay adjustment modes based on the current skew condition. During initial calibration, coarse steps are applied for rapid convergence, then fine steps are used for precision tuning. This dynamic approach optimizes both adjustment speed and precision without requiring a complex single-stage mechanism.
2Measurement precision
If iterative measurement and adjustment is performed, then clock skew synchronization accuracy is improved, but loss of time increases
Solution Approach 1:
Coarse delay adjustments are applied as preliminary action to bring the clock skew close to the target synchronization point before fine adjustments are made. This preliminary positioning reduces the number of iterative fine adjustment cycles needed, thereby maintaining high synchronization accuracy while minimizing the total adjustment time.
Solution Approach 2:
The adjustment process uses periodic measurement and correction cycles, where the clock skew is measured, adjusted based on the measured error, and re-measured in repeated cycles. This periodic feedback mechanism ensures convergence to the optimal synchronization point while controlling the total adjustment time through structured iteration.
3Productivity
If coarse delay steps are applied, then productivity of skew adjustment is improved, but manufacturing precision of delay setting decreases
Solution Approach 1:
The delay adjustment is segmented into coarse steps for rapid positioning and fine steps for precision setting. The coarse steps provide high productivity by making large adjustments quickly, while the fine steps restore manufacturing precision by enabling granular control. This segmentation resolves the contradiction by applying different resolution levels at different stages of the adjustment process.
Solution Approach 2:
The system dynamically transitions from coarse to fine delay adjustment as the synchronization point is approached. This dynamic switching allows the system to maximize productivity during the initial adjustment phase when large skew corrections are needed, then switch to high-precision fine adjustments near the target, achieving both speed and accuracy.
Data Source
AI summary
Embodiments of the present disclosure describe techniques for implementing enhanced skew control for synchronizing two clock meshes in an IC or chip. A disclosed skew adjust control, methods, and systems enable effective and efficient operations to optimize a coarse delay setting to maintain for a functional mode of operation of the system, where only fine delay steps are applied to an adjustable one of the clock meshes, based on measured clock skew, to synchronize the clock meshes.