Equivalent Waveform Generation for IC Timing Analysis
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Solution Overview
Problem
Current timing and signal integrity analysis methods in integrated circuit design are inadequate in accurately modeling distorted waveforms caused by crosstalk, leading to timing violations and errors, especially at smaller feature sizes where cross coupling becomes significant.
Innovation Solution
A method to generate an equivalent waveform based on the transition quantity required for an integrated circuit element, using only conventionally stored characteristics like delay and slew, allowing for real-time calculations without requiring additional characterization or complex curve fitting techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional timing analysis methods using simple input waveforms are used, then the analysis is fast and easy to perform, but the accuracy of timing analysis deteriorates due to inability to accurately model distorted waveforms caused by crosstalk
Solution Approach 1:
The patent transforms the distorted input waveform into an equivalent non-distorted waveform by changing the parameter representation. Instead of directly modeling the complex distorted waveform, the method computes a transition quantity from the distorted waveform and uses this scalar parameter to define an equivalent non-distorted waveform that produces the same output, thereby maintaining accuracy while simplifying the modeling approach
Solution Approach 2:
The patent creates an equivalent copy of the distorted waveform in the form of a non-distorted waveform. This equivalent waveform is not a direct copy but a transformed representation that captures the essential timing characteristics (transition quantity) of the original distorted waveform, allowing accurate timing analysis without dealing with the complexity of the actual distorted shape
2Measurement precision
If accurate modeling of distorted waveforms is attempted using complex methods, then timing analysis accuracy improves, but the computational time and complexity increase
Solution Approach 1:
The patent reduces the complexity of waveform modeling by transforming the problem from modeling the entire distorted waveform shape to computing a single transition quantity parameter. This parameter transformation enables accurate equivalent waveform generation using only standard cell library characteristics (delay and slew), avoiding time-consuming complex curve fitting or additional characterization while maintaining high accuracy
Solution Approach 2:
The patent extracts the essential timing characteristic (transition quantity) from the complex distorted waveform. By separating this key parameter from the rest of the waveform complexity, the method enables efficient computation using only the extracted transition quantity and standard cell characteristics, eliminating the need for complex full-waveform analysis
3Productivity
If crosstalk effects are ignored in timing analysis, then the analysis process is simpler and faster, but timing violations are not detected accurately
Solution Approach 1:
The patent converts the harmful effect of crosstalk-induced waveform distortion into a useful computational approach. Instead of trying to eliminate or avoid modeling crosstalk effects, the method uses the transition quantity derived from the distorted waveform (which includes crosstalk) to create an equivalent non-distorted waveform. This transforms the problem of dealing with distorted waveforms into a benefit, enabling accurate timing analysis that accounts for crosstalk while maintaining computational efficiency
Data Source
AI summary
An equivalent waveform for a distorted waveform used in timing and signal integrity analysis in the design of an integrated circuit is automatically generated. The equivalent waveform is produced by calculating the transition quantity of a first non-distorted waveform. The transition quantity is the amount of transition of the first non-distorted waveform that is required for the cell to produce an output waveform with a predetermined end voltage. The end point of the transition period for the distorted waveform is then determined based on when the distorted waveform has accumulated the same transition quantity. The equivalent waveform can then be formed by computing a second non-distorted waveform such that the end point of the transition period for the second non-distorted waveform coincides with the end point of the transition period for the distorted waveform.