Voltage-Based Transient EM-IR Drop Analysis for IC Power Networks
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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 voltage, high computational costs, and storage requirements, especially when dealing with fast-switching currents and RC effects.
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 concurrently determine currents for EM and IR drop analysis, considering actual devices and RC effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-stage analysis is performed to obtain current through each device path, then EM and IR drop analysis can be conducted, but computational cost increases due to extra device model evaluations and iterations
Solution Approach 1:
The patent segments the power network into multiple partitions and performs independent transient analysis on each partition rather than analyzing the entire network globally. This segmentation reduces the computational complexity and number of device model evaluations required, thereby improving computational efficiency while maintaining analysis accuracy through subsequent global aggregation of results
Solution Approach 2:
The patent performs preliminary transient analysis to compute device currents before conducting the actual EM and IR drop analysis. By pre-calculating the current waveforms through each device path and storing them for later use, the method avoids repeated computational iterations, reducing overall computational cost while ensuring accurate EM and IR drop evaluation
2Measurement precision
If full waveforms of device currents are stored for EM analysis, then accurate EM analysis can be performed, but storage space requirements increase
Solution Approach 1:
The patent extracts only the essential current waveform data needed for EM analysis from the full device current signals. By identifying and storing only the relevant current components that contribute to electromigration effects, rather than preserving complete waveform information, the method reduces storage requirements while maintaining sufficient accuracy for EM evaluation
Solution Approach 2:
The patent applies partial action by computing and storing current waveforms for only those device paths that are critical to EM and IR drop analysis, rather than maintaining full waveform data for all devices in the network. This selective approach reduces storage space consumption while preserving analysis accuracy for the most impactful current paths
3Measurement precision
If very small timesteps are used to solve linear RC circuit with fast switching currents, then high accuracy is achieved, but computation speed decreases
Solution Approach 1:
The patent implements dynamic timestep adjustment in the transient analysis of linear RC circuits. The simulation automatically varies the timestep size based on the switching activity and circuit state, using smaller timesteps only when fast switching currents occur and larger timesteps during stable periods. This dynamic approach maintains high accuracy during critical switching events while improving overall computation speed by reducing the total number of timesteps required
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides more accurate and efficient analysis results by accounting for actual devices and RC effects, reducing computational costs and storage needs, while improving the realism of analysis outcomes.
Implementation Method 1
RC effects cause the applied voltage at a circuit path to differ from VDD
Implementation Method 2
Due to the resistance of interconnects in the power networks, there is a voltage drop across the network, commonly referred to as IR drop
Implementation Method 3
Electromigration (EM) is an effect on a circuit caused by movement of ions in a conductor structure
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.