MOS Table Models for Fast and Accurate Simulation of Analog and Mixed-Signal Circuits Using Efficient Oscillation-Diminishing Interpolations

In this paper, we propose an efficient oscillation-diminishing cubic Hermite spline interpolation method for the table-based transistor model approximation. We use the cubic Hermite spline interpolation to ensure the continuity of the derivatives. Oscillation-diminishing techniques are proposed to reduce the oscillations (bumps) of interpolations such that both convergence and accuracy are significantly improved. Further, the oscillation-diminishing schemes do not rely on any real derivatives. Therefore, the proposed method can be used to build table models from measured data of the physical devices, where the real derivatives are not always available. In the proposed method, an adaptive approach is employed to generate the nonuniform interpolation grids such that the interpolation accuracy is guaranteed and the memory requirement is minimized. We also propose a novel combined exponential extrapolation method for off-state (leakage) current, which exactly follows the exponential-decay characteristic of that current. Test simulations on several classic industrial analog and mixed-signal circuits show that the proposed method can achieve high accuracy with lower computational cost compared with existing table-based model approximation methods.