Waveform Memory System for Accurate Static Timing Analysis
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Solution Overview
Problem
Current static timing analysis (STA) methods in circuit design lack the accuracy needed to account for waveform effects, as they rely on simplified slew information, which can lead to significant errors due to the omission of detailed waveform data, making it costly and impractical to maintain comprehensive waveform information for all pins in a design.
Innovation Solution
A waveform memory system is introduced that efficiently stores and propagates detailed waveform information throughout the STA process, using dense and sparse storage methods, compression, and merge operations to ensure accurate timing analysis, and includes a waveform storage manager, compression, and decompression modules to handle and process waveforms effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detailed waveform information is maintained for all pins in traditional STA, then measurement precision of timing analysis is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent applies local quality by differentiating between critical and non-critical pins in the circuit design. Detailed waveform information is maintained only for critical pins where timing accuracy is paramount, while non-critical pins use simplified slew information. This selective approach improves timing analysis accuracy for critical paths without incurring the full cost of maintaining detailed waveforms for all pins, thus resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent implements partial action by maintaining detailed waveform information for only a subset of pins (critical pins) rather than all pins. The system identifies critical pins based on their impact on timing analysis and applies comprehensive waveform tracking only where necessary. This partial approach achieves sufficient timing analysis accuracy while avoiding the excessive complexity and cost of full-waveform maintenance across the entire design.
2Device complexity
If simplified slew information is used in STA, then device complexity is reduced, but measurement precision of timing analysis deteriorates due to waveform effects
Solution Approach 1:
The system applies different levels of information detail to different pins based on their criticality. Critical pins receive detailed waveform information to capture waveform effects accurately, while non-critical pins use simplified slew information. This local differentiation maintains acceptable timing analysis precision while managing device complexity, resolving the contradiction between these two parameters.
Solution Approach 2:
The patent introduces an intermediary classification mechanism that categorizes pins as critical or non-critical based on their timing impact. This intermediary layer allows the system to apply appropriate levels of waveform detail selectively, bridging the gap between simplified slew information and comprehensive waveform tracking, thereby maintaining precision where needed while controlling overall complexity.
3Measurement precision
If comprehensive waveform information is propagated through all circuit stages, then measurement precision is improved, but loss of time and computational resources increases
Solution Approach 1:
The patent applies local quality by propagating detailed waveform information only through circuit stages and pins that are critical to timing analysis. Non-critical paths use simplified slew information propagation. This selective propagation maintains high measurement precision for critical timing paths while significantly reducing the computational time and resources required compared to comprehensive waveform propagation across the entire design.
Solution Approach 2:
The system implements partial action by performing comprehensive waveform propagation only for critical circuit paths and stages identified through analysis. For non-critical paths, simplified slew information propagation is sufficient. This partial approach achieves adequate timing analysis precision while avoiding the excessive computational time and resource consumption of full-waveform propagation throughout the entire circuit.
Data Source
AI summary
Accurate timing analysis during STA is performed using detailed waveform information in addition to the traditional slew information. A waveform memory system efficiently stores the detailed waveforms that are used in, calculated during, and propagated throughout timing analysis for a circuit design. During the STA process, for multiple modeled stages of circuit design, a waveform including information detailing the form of the waveform is compressed, stored in, decompressed, and retrieved from a memory system. The memory system provides for storage efficiencies including long-term and short-term storage areas, multi-level storage, and separate storage for each view evaluated during the STA.