What is a Common Mode Choke?

A common mode choke is an electrical filter that blocks high frequency noise common to two or more data or power lines while allowing the desired DC or low-frequency signal to pass.  Common mode (CM) noise current is typically radiated from sources such as unwanted radio signals, unshielded electronics, inverters and motors. Left unfiltered, this noise presents interference problems in electronics and electrical circuits.

How do Common Mode Chokes Work?

In normal or differential mode (single choke), current travels on one line in one direction from the source to the load, and in the opposite direction on the return line that completes the circuit.  In common mode, the noise current travels on both lines in the same direction

In common mode, the current in a group of lines travels in the same direction so the combined magnetic flux adds to create an opposing field to block the noise, as illustrated by the red and green arrows in the toroid core shown in Figure 1. In differential mode, the current travels in opposite directions and the flux subtracts or cancels out so that the field does not oppose the normal mode signal.

How do I Choose a Common Mode Choke?

The main criteria for selecting a common mode choke are:

• Required impedance: How much attenuation of noise is needed?

• Required frequency range: Over what frequency bandwidth is the noise?

• Required current-handling: How much differential mode current must it handle?

Why FKS Choose Electronic?

If you have decided on buying common mode chokes for your application, you can do so at FKS Electronic. We are the best inductor and transformer manufacturers in CHINA, our factorty has 15years experence of of the transformers and inductors manufacture,who offer both common mode and differential mode chokes. While common mode chokes are effective to filter supply and return conductors with in-phase signals of equal amplitude, differential mode inductors help in filtering out-of-phase or uneven amplitude signals. 

FKS Electronics’ inductor style common mode chokes are designed to provide the highest common mode impedance over the widest frequency range. They are more efficient at producing the needed inductances. And, every inductor provided here is RoHS and REACH compliant. So, make sure you get all your transformers and inductors here.