Common Mode Choke
Common mode choke is commonly used in computer switching power supply to filter common mode electromagnetic interference signals. In PCB design, the common mode inductor also acts as EMI (electro magnetic interference) filtering, which is used to suppress the outward radiations of the electromagnetic waves generated by the high-speed signal line.
We can divide electromagnetic interference into two categories: serial mode interference (differential mode interference) and common mode interference (ground interference). Take the two PCB traces on the motherboard (the traces connect the components of the motherboard) as an example. The so-called series mode interference refers to the interference between two traces. While the common mode interference is the interference caused by the potential difference between the two traces and the PCB ground.
Currently, small domestic common mode inductors use high frequency suppression measures with common mode choke coil structure, having various advantages like small size, easy to use, good balance, high quality, the signal is not decay and so on. They are widely used in double balanced tuning device, multi-frequency transformers, impedance transformers, balanced and unbalanced transformers, etc.
Another common-mode filter inductor/ EMI filter inductor use ferrite core which is difficult to deform in high-speed signal, having various advantages like small size, easy to use, with good balance, easy to use, high quality and so on. They are widely used in the electronic equipment of suppressing EMI noise, personal computers and peripherals USB lines, DVC, STB IEEE1394 lines, LCD panels, low-voltage differential signals, etc.