US Patent 7600203 Circuit design system and circuit design program

A circuit design system has: a storage unit in which a netlist is stored; a fault-candidate extracting module configured to extract equivalent fault class Gi from the netlist; a judgment module configured to select a target node out of a plurality of nodes Ni1 to Niji included in the equivalent fault class Gi, wherein Ji is a number of nodes included in the equivalent fault class Gi; and an observation-point inserting module configured to update the netlist by inserting at least one observation point into the target node. The judgment module decides the target node based on the number Ji.