State transformation in event driven explicit simulation

Abstract

This paper presents a general method for incorporating state transformation in event driven explicit simulation. One inherent assumption in this type of simulation algorithm is the state independence, which allows the algorithm to process the states independently in an event driven manner at the transistor level. Numerical problems arise when an inappropriate state representation of the circuit, in which the states are not truly independent, is chosen. In principle, any similarity transformation of the state equation can be employed to transform the circuit into a more convenient state space for numerical solution. This paper develops a systematic scheme to derive an appropriate state transformation, and to incorporate the state transformulation in such a way to maintain the efficiency of event driven explicit simulation algorithms.