Programmable Clock Delay Optimization for FPGA Timing
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Solution Overview
Problem
Circuit designers face challenges in meeting aggressive timing requirements for FPGA circuit designs, as automated CAD tools often fail to resolve timing violations, leading to significant manual effort and resource expenditure.
Innovation Solution
The method involves determining and adjusting the delay values of programmable delay circuits in clock leaves to optimize timing, predicting the impact on slacks of cells, and reconnecting target cells to minimize timing degradation, using automated EDA systems to manage clock signal delays and connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If automated place and route EDA solutions are used to optimize circuit design, then device complexity is reduced, but timing requirements cannot be met
Solution Approach 1:
The system performs self-optimization by automatically analyzing timing slacks, predicting the impact of delay changes, and adjusting programmable delay circuits without requiring manual designer intervention. The EDA tool serves itself to resolve timing violations that it cannot handle through conventional place and route methods.
Solution Approach 2:
The invention changes the delay parameter of programmable delay circuits associated with clock leaves to optimize timing. By adjusting these delay values and predicting their impact on cell slacks, the system meets timing requirements while maintaining automated operation.
2Manufacturing precision
If manual effort is increased to resolve timing violations, then timing requirements are met, but productivity decreases
Solution Approach 1:
The system automates the entire timing optimization process, from analyzing current slacks to predicting the impact of delay changes and implementing adjustments. This self-service approach eliminates the need for manual timing closure efforts while maintaining high timing precision, thereby improving productivity.
Solution Approach 2:
The system continuously monitors timing slacks of cells and uses this feedback to predict whether changing delay values will improve or degrade timing. This closed-loop feedback mechanism enables automatic timing optimization without manual intervention, resolving the contradiction between precision and productivity.
3Manufacturing precision
If delay value of a programmable delay circuit is changed to resolve timing violation, then timing of target cell is improved, but timing of other cells may degrade
Solution Approach 1:
Before changing the delay value of a programmable delay circuit, the system predicts the impact on all cells connected to that clock leaf. By anticipating potential timing degradation in other cells and selecting appropriate delay values, the system prevents harmful side effects before they occur.
Solution Approach 2:
The optimization is performed at the level of individual clock leaves and their associated cells. By making localized delay adjustments to specific programmable delay circuits and predicting their impact on connected cells, the system improves timing for target cells while maintaining or improving timing for other cells through selective local optimization.
Data Source
AI summary
Disclosed approaches for processing a circuit design include determining first slacks of cells, including a target cell, coupled to receive a clock signal through a first clock leaf. The first slacks are based on a current delay value specified for a first programmable delay circuit. The method predicts second slacks of the cells based on another delay value specified for the first programmable delay circuit, and then determines whether or not the second slacks indicate a degradation in timing relative to the first slacks. The current delay value of the first programmable delay circuit is adjusted to the other delay value in response to determining the second slacks indicates no degradation in timing. The target cell is reconnected to receive the clock signal from a second clock leaf having a second programmable delay circuit specified with the other delay value in response to determining the second slacks indicates degradation in timing.