Functional abstraction of logic gates for switch-level simulation

Abstract

Switch-level simulation has become a common means accurate modeling of MOS circuit behavior. In this paper, the authors propose a new method for detecting logic gate implementation and accurately modeling their switch-level behavior. The functional abstraction replaces logic gate implementation in the switch-level description with an accurate high-level model which incorporates all relevant switch-level phenomena. The switch-level accuracy of the simulation is, therefore, preserved. However, since the gate implementations are modeled at a higher, more abstract level, the simulation speed is greatly increased. The functional abstraction is automatic and completely transparent to the user. Detection of a gate is determined by expressing the logic function of a transistor network in the sum-of-product notation and is not limited to a specific design style. The proposed algorithms have been implemented and tested on several large circuits, including a complete microprocessor. For this processor, 85% of all transistors were substituted with high-level models. A significant decrease in simulation time and storage requirement occurred for these circuits when gate abstraction was performed.<>