Understanding the difference between common mode signals and differential mode signals is extremely important as users need to know what the circuit requires to reduce noise. How do customers know if the noise is differential or common mode? One way to test whether the problem is common mode or differential mode would be to attach a Würth Elektronik Midcom snap cable ferrite to the cable in question. If there is an improvement in the reduction of noise after the snap cable ferrite is attached, the problem is common mode. If not, then there is a differential problem. This presentation will discuss the common mode issues and focus on the surface mount product line as the solution. Common mode chokes are used to reduce a specific type of electrical noise known as Common Mode Noise. They are also referred to as Current Compensated chokes or Current Cancellation chokes. Common mode chokes work well in applications like AC/DC power supplies (lines with large current flow) and signal lines, where distortion of the signal will create problems. When it comes to AC power, common mode noise is the noise signal between the ground and neutral/phase. These tend to have higher frequency ranges than differential mode noise due to the fact that these originate from differential mode signals that are inductively or capacitively coupled.