Delay Calculation Engine for Clock Jitter Analysis
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Solution Overview
Problem
Current timing analysis methods, particularly for high-speed and high-performance integrated circuit designs, face inefficiencies due to the large number of timing paths and the reliance on standard library models that do not accurately reflect actual IR-drop induced jitter, leading to pessimistic timing margins.
Innovation Solution
A delay calculation engine is employed to analyze clock jitter by generating timing graphs that include IR drop and time delay properties, allowing for more precise calculation of jitter effects, thereby improving the accuracy of timing analysis without the need for excessive resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard library timing models are used for timing analysis, then the analysis process is simple and fast, but the timing margins become pessimistic and inaccurate for high-speed designs
Solution Approach 1:
The patent changes the fundamental parameters of timing analysis by introducing IR drop calculations and delay corner simulations. Instead of using fixed library models, the system dynamically calculates timing parameters based on actual circuit conditions, including voltage drops across interconnects and process variations, thereby achieving accurate jitter measurement without sacrificing analysis speed
Solution Approach 2:
The patent replaces the conventional mechanical approach of using pre-defined library timing models with a computational simulation system. The delay calculation engine performs virtual simulations of timing paths under various IR drop conditions, substituting the need for pessimistic margins with accurate predictive modeling of actual timing behavior
2Reliability
If the number of timing paths is increased to capture all possible paths, then timing analysis completeness improves, but computational resources and time consumption increase exponentially
Solution Approach 1:
The patent segments the timing analysis process into manageable components by organizing timing paths into hierarchical structures and grouping similar paths together. The delay calculation engine processes paths in segments based on circuit stages and IR drop regions, reducing the computational burden while maintaining complete analysis of all timing paths
Solution Approach 2:
The patent applies partial action by focusing computational resources on critical timing paths that have the most significant impact on overall timing margins. The delay calculation engine identifies and prioritizes paths based on their sensitivity to IR drops and timing constraints, performing detailed analysis only where necessary rather than uniformly processing all paths
3Reliability
If pessimistic timing margins are used to account for IR drop induced jitter, then timing reliability is improved, but the available clock period is reduced and performance is compromised
Solution Approach 1:
The patent introduces feedback mechanisms where the delay calculation engine continuously monitors and calculates actual IR drop values during timing analysis. These calculated IR drop values are fed back into the timing margins, allowing the system to adjust margins dynamically based on actual circuit conditions rather than using fixed pessimistic values, thereby optimizing both reliability and clock speed
Data Source
AI summary
The present embodiments are generally directed to analyzing clock jitter. Jitter affects the clock delay of the circuit and the time the clock is available at sync points, so it is important to calculate its impact correctly to take appropriate margin during timing analysis. Jitter could be due to various reasons—one of them is due to IR Impact on the Clock Tree. IR drop variations between the two consecutive cycles can effectively reduce the available clock period for data to be correctly captured.