Common mode inductance is also called common mode choke, which is essentially a two-way filter: on the one hand, it must filter out common-mode electromagnetic interference on the signal line, and on the other hand, it must suppress itself from emitting electromagnetic interference to avoid affecting the same electromagnetic The normal operation of other electronic equipment in the environment. Common mode inductors also play the role of EMI filtering, which is used to suppress the radiated emission of electromagnetic waves generated by high-speed signal lines.