Since using the Modified Nodal Approach formulation it is possible to obtain exact first and second arder sensitivities of any linear circuit with an affordable computational cost, first and second arder optimization algorithms may be implemented. A personal-computer program (CiOpt) to optimize the frequency response of linear lumped circuits has been implemented. It' s output are the element values that best match the obtained and the desired frequency response. CiOpt has preved to be an efficient tool in device modelling and in improving designs where the inclusion of more accurate device models distorts the desired frequency response. The implemented optimization algorithms -a quasi-Newton method (Fletcher-Powell), Newton's method and an algorithm based on the Levenberg-Marquardt method- are compared on an application example.