Clock Distribution Feedback Layout for Precise Phase Adjustment
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Solution Overview
Problem
Conventional clock distribution circuits face challenges in accurately adjusting clock phases due to manufacturing discrepancies, particularly in advanced miniaturization processes, where systematic and random factors influence timing discrepancies, leading to reduced precision in phase adjustments.
Innovation Solution
A clock distribution circuit design with a branch point located near the clock driver, allowing for a feedback path that minimizes the influence of discrepancies and enables highly accurate phase adjustments by using a reference clock signal and feedback signal synchronization, and optimizing the placement of feedback paths based on layout data and design margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional feedback loop routing methods are used with independent routes from clock drivers to sequential circuits, then device complexity is reduced, but manufacturing discrepancies cause reduced measurement precision in phase adjustments
Solution Approach 1:
The patent merges the feedback route with the clock distribution route by having the feedback signal travel through the same clock driver and wiring infrastructure. This consolidation ensures that both the clock signal and feedback signal experience identical manufacturing discrepancies, allowing accurate phase measurement despite process variations.
Solution Approach 2:
The patent segments the feedback mechanism by introducing dedicated delay adjustment circuits at each clock driver stage. These segmented adjustment circuits allow independent calibration of delay at each stage, compensating for manufacturing discrepancies while maintaining the merged route structure.
2Reliability
If timing margins are increased to compensate for manufacturing discrepancies, then reliability is improved, but productivity is reduced due to larger timing margins consuming more cycle time
Solution Approach 1:
The patent implements feedback mechanisms that measure actual phase differences and automatically adjust delay settings to compensate for manufacturing discrepancies. This active feedback approach replaces passive timing margins with dynamic compensation, maintaining reliability while reducing the need for excessive timing margins.
Solution Approach 2:
The patent changes the delay parameter dynamically through adjustable delay circuits that can be calibrated to match actual manufacturing variations. By adjusting the delay parameter based on measured discrepancies, the system maintains accurate timing without requiring fixed large timing margins.
3Measurement precision
If multiple phase adjustment mechanisms such as PLLs or DLLs are used throughout the chip, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces delay adjustment circuits as intermediary elements between the clock driver and sequential circuits. These intermediary circuits provide the necessary phase adjustment functionality without requiring complex PLL or DLL mechanisms, simplifying the overall system while maintaining precision.
4Adaptability or versatility
If feedback paths are extended to reach distant sequential circuits, then adaptability is improved, but manufacturing discrepancies cause increased loss of time in feedback signal propagation
Solution Approach 1:
The patent applies local quality by placing delay adjustment circuits at each clock driver stage along the feedback path. This allows local compensation for delay variations at each segment of the feedback path, enabling the system to adapt to distant sequential circuits while compensating for propagation time differences caused by manufacturing variations.
Data Source
AI summary
A clock distribution circuit is provided with a clock generation circuit configured to generate a clock signal, a clock distribution network in which the clock signal is distributed, and a sequential circuit configured to operate on the clock signal distributed through a branch point of the clock distribution network. The clock distribution circuit is further provided with a clock generation circuit configured to input as a feedback signal the clock signal that has branched from the branch point and to output the clock signal to the clock distribution network based on the inputted feedback signal and a reference clock signal. The branch point is provided at a clock driver near the clock generation circuit, among preceding stage clock drivers of the sequential circuit of the clock distribution network.