1. A method for generating model files of target devices of an integrated circuit, the method comprising: providing the target devices; providing a device target set for the target devices, wherein the device target set comprises target values of parameters of the target devices; determining a nearest known model related to the target devices, wherein the nearest known model comprises a first model file; performing a sensitivity analysis to determine sensitive parameters in the first model file; modifying the sensitive parameters in the first model file to generate a second model file; and determining a fitness value of a circuit simulated using the second model file with values of parameters in the device target set.