Translation of automotive module RF immunity test limits into equivalent IC test limits using S-parameter IC models

A method to translate immunity specifications of automotive modules into equivalent requirements at integrated circuit (IC) level, using linear scattering parameter models of the ICs, is presented. A technique is described to determine S-parameters of ICs by simulations based on back-annotated analog schematics. The simulation results are compared with measurement data obtained using a specially designed test board. As an example, simulation and measurement results are given for the input stage of an automotive sensor interface. A good agreement is obtained from the lowest test frequency up to 1 GHz. Above this value, the measured results seem to be dominated by package effects.