Two-Stage Voltage-Based EM-IR Drop Analysis for Power Gates
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Solution Overview
Problem
Current methods for analyzing IR drop and electromigration in power distribution networks within integrated circuits are inefficient and inaccurate due to assumptions of constant VDD voltage, high computational costs, and storage requirements for current waveforms, especially with modern circuit designs and fast switching currents.
Innovation Solution
A two-stage voltage-based approach for transient EM-IR drop analysis, where the first stage calculates voltages at interface nodes and creates a new netlist, and the second stage performs simulation using these voltage values to analyze IR drop and electromigration, considering actual devices and RC effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage analysis approach is used to perform IR drop and EM analysis, then the analysis can be performed separately from simulation, but it requires solving for current values which increases computational cost and storage requirements
Solution Approach 1:
The patent inverts the conventional two-stage approach by performing EM analysis first to obtain electromigration currents, then using these currents as inputs for IR drop analysis. This reversal eliminates the need to solve for current values during simulation, reducing computational complexity while maintaining analysis accuracy
Solution Approach 2:
The patent segments the analysis into distinct phases: EM analysis phase that extracts electromigration currents from simulation data, and IR drop analysis phase that uses these currents as inputs. This segmentation allows each analysis to be performed independently with optimized computational requirements, avoiding the need to simultaneously solve both analyses
2Measurement precision
If current waveforms are stored for EM analysis, then accurate EM and IR drop analysis can be performed, but large amounts of storage space are required
Solution Approach 1:
The patent extracts only the necessary electromigration current values from simulation data during the EM analysis phase, rather than storing complete current waveforms. By performing EM analysis separately and extracting only the required current parameters, the method achieves accurate analysis with minimal storage requirements
Solution Approach 2:
The patent performs EM analysis preliminarily before IR drop analysis, obtaining electromigration currents in advance. These pre-computed currents are then used as inputs for IR drop analysis, eliminating the need to store and process full current waveforms throughout the entire analysis process
3Ease of operation
If constant VDD voltage assumption is used, then analysis is simplified, but accuracy decreases due to ignoring RC effects and voltage variations
Solution Approach 1:
The patent transitions from the static constant VDD voltage assumption to a dynamic approach where voltages are computed based on actual device switching activities and RC network effects. The method dynamically updates voltage values during EM and IR drop analysis, capturing transient effects while maintaining computational efficiency through the segmented analysis approach
Data Source
AI summary
A system, method, and computer program product is disclosed for performing electrical analysis of a circuit design. A voltage-based approach is described for performing two-stage transient EM-IR drop analysis of an electronic design. A two-stage approach is performed in some embodiments, in which the first stage operates by calculating the voltage at certain interface nodes. In the second stage, simulation is performed to simulate the circuit to concurrently obtain the current at the interface nodes. In some embodiments, multiple adjacent devices as identified as interface devices for purposes of the analysis. One situation where it may be useful to analyze a larger portion of the circuitry in this way where the analysis is being performed on a netlist having a power gate.