Abstract: A mixed mode simulation method and apparatus are provided for highly accurately simulating the total characteristics of a digital analyzed circuit portion and an analog analyzed circuit portion, which are both subjected to mixed mode simulation, in consideration of the influence exerted on the analog analyzed circuit portion by a current consumed by the digital analyzed circuit portion. More particularly, a current value of an equivalent circuit for current calculation modeled for providing the analog analyzed circuit portion with a current generated due to an operating state of the digital analyzed circuit portion realized by logic simulation is determined in synchronism with the logic simulation, and the equivalent circuit for current calculation derived thereby is composed with the analog analyzed circuit portion, and this composite circuit is subjected to circuit simulation.

Abstract: In verifying an LSI layout pattern, the whole layout pattern is converted into circuit data and a subcircuit to be verified is picked up and subjected to simulation. After converting the layout pattern into the transistor level circuit data, the transistor level circuit data is transformed into a logic gate level circuit data while judging a clocked gate included in the subcircuit. After picking up a subcircuit in a predetermined manner, an approximate load is connected to the interface port of the picked-up subcircuit.