Analog Centric Current Modeling in Mixed-Signal Verification
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Solution Overview
Problem
Current mixed-signal circuit design simulations face inaccuracies due to the lack of current loading at the analog/digital boundary, leading to timing and level errors, and inadequate measurement of leakage current.
Innovation Solution
Implementing current loading at the analog/digital boundary and using techniques to accurately measure and model leakage current, ensuring that current properties are directly reflected and propagated between digital and analog simulators, allowing for accurate modeling of current load features and leakage current measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If digital simulator is used to simulate digital circuit aspects, then simulation speed is improved, but current loading at analog/digital boundary is lost leading to timing and level errors
Solution Approach 1:
The patent introduces a boundary interface with current loading mechanisms as an intermediary between the digital simulator and analog simulator. This interface includes current sources and control logic that mediate the interaction at the analog/digital boundary, ensuring proper current loading effects are applied while maintaining the speed advantage of digital simulation for digital circuit aspects.
Solution Approach 2:
The patent merges the digital simulator and analog simulator into a unified mixed-signal simulation environment with integrated current loading control. The boundary interface combines digital control signals with analog current sources, allowing both simulators to work together seamlessly with proper current loading effects at their interface.
2Reliability
If analog simulator is used to simulate analog circuit aspects, then simulation accuracy is improved, but simulation speed deteriorates
Solution Approach 1:
The patent segments the circuit design into digital circuit aspects and analog circuit aspects, allocating each to the appropriate simulator type. Digital circuit aspects are simulated by the fast digital simulator, while analog circuit aspects requiring high accuracy are simulated by the analog simulator, optimizing the overall simulation performance by matching simulator strengths to circuit characteristics.
3Device complexity
If current loading is not applied at analog/digital boundary, then device complexity is reduced, but timing and level errors occur
Solution Approach 1:
The boundary interface is designed to automatically apply current loading effects based on the interaction between digital and analog simulators. The interface monitors boundary voltages and automatically adjusts current loading without requiring complex external control, allowing the simulation system to self-regulate the current loading effects for accurate timing and level behavior.
4Measurement precision
If leakage current is not accurately measured, then measurement precision is reduced, but circuit behavior mistakes occur
Solution Approach 1:
The patent implements feedback mechanisms where the boundary interface continuously monitors boundary voltages and currents, and uses this information to adjust simulation parameters and detect leakage current effects. The feedback loop ensures that leakage current is accurately measured and accounted for in the simulation, preventing mistakes in circuit behavior analysis.
Data Source
AI summary
A method includes operating a digital simulator to mimic loading effects of digital circuit blocks of a circuit design on analog circuit blocks of the circuit design. The digital simulator sets a current signal timing and a current level value at an analog/digital boundary between the digital circuit aspects and the analog circuit aspects. The analog simulator is operated to apply the current signal timing and the current level value to simulate the analog circuit blocks.