Common mode chokes are used to suppress spurious radiation and ensure functional safety. They are found in switching power supplies and in components for signal transmission. They are inductive transformer components consisting of several windings wound in opposite directions. The transformer core is made of ferromagnetic material. In terms of function, common-mode chokes with their high impedances suppress concurrent interference signals on the signal lines. The situation is different for the useful signals, which are of lower frequency and are transmitted in push-pull mode.
Common-mode chokes are used, among other things, in automotive technology, where they separate the interference radiation from the signal transmission. In this example, it is interference radiation that is interspersed in the local networks of the motor vehicles and that impairs the functioning.