SPICE Corner Model Generation for Opposite MOSFET Variations

The patent pre-calculates and stores ratio values between same-directional and opposite-directional variation magnitudes in a ratio table during the model generation phase. This preliminary action enables the simulation phase to quickly retrieve and apply appropriate ratios without performing time-consuming Monte Carlo simulations, thus resolving the contradiction between verification capability and simulation time.

The patent creates simplified corner models for opposite-directional variations by copying and scaling the characteristics from same-directional corner models using pre-stored ratios. Instead of performing full Monte Carlo simulations, the system generates approximate opposite-directional corner models by applying ratio factors to existing model parameters, significantly reducing simulation time while maintaining adequate verification accuracy.

The patent creates a universal ratio table that can be applied to any combination of MOSFETs (NFETs and PFETs) regardless of their specific types or thresholds. The same ratio table serves all verification needs by providing scaling factors that work across different device combinations, eliminating the need to prepare separate corner models for each possible MOSFET pair while maintaining comprehensive verification capability.

The patent transforms the verification approach by changing from preparing complete corner model datasets for all combinations to storing compact ratio parameters. These ratio parameters can be dynamically applied to generate appropriate corner models for any MOSFET combination during simulation, reducing data preparation time while maintaining the ability to verify all combinations through parameter scaling rather than exhaustive pre-computation.