In computer switching power supplies, common mode chokes are often employed to filter common mode electromagnetic interference signals. In PCB design, common mode inductors also serve to filter EMI.
About its theoretical knowledge
The motherboard inside the computer is mixed with various high-frequency circuits, digital circuits and analog circuits.
EMI: This refers to the large amount of high-frequency electromagnetic waves that interfere with each other during operation.
Electromagnetic interference can be divided into two categories: series mode interference and common mode interference.
Series mode interference: refers to the interference between two traces.
Common mode interference: interference caused by the potential difference between two traces and the PCB ground line.
If the common mode current generated by the board is not attenuated and filtered, it can easily cause electromagnetic radiation through the interface data line.
Hence, the filter circuit must be appropriately designed to filter both common mode and differential mode interference.
Common mode inductors function as two-way filters. They filter out common mode electromagnetic interference on the signal line and suppress their own electromagnetic emissions.
The above is an introduction to what common mode inductors are.
