A standard form is presented for describing device characteristics in VLSI's. It serves as a standard interchange form for device characteristics between various design tools for VLSI's. The form is designed such that any relevant characteristic as a circuit component can be described. It also makes it possible to process an enormous amount of device data efficiently. A newly developed CAD system, which integrates device and circuit simulators, is also presented as a standard form application example. Any device simulator, which has outputs in the standard form, can be implemented into the system. By using the standard form, various device simulators are able to be used in total LSI design systems, which makes it possible to execute accurate simulations and designs for LSI using recent fine pattern technologies.