How to Select and Use Ferrite Cores
Filtering is defined as separating electromagnetic noise from a signal to reduce the amount of noise a cable will radiate or conduct. There are three methods used to filter out EMI from a signal: 1. Frequency separation, 2. Current mode separation, and 3. Voltage separation. Frequency separation relies on impedance within capacitors, inductors, and ferrite cores. Current mode separation is based upon defining a current as common mode or normal (differential) mode, isolating those currents and filtering those either by using a common mode choke, capacitor, inductor, or ferrite core. Voltage separation is based solely on using varistors to either limit or suppress EMI. KGS’ high impedance ferrite cores can be used for current mode separation.
- Frequency separation
capacitor, inductor, ferrite core
- Current mode separation (Common mode or normal mode)
common mode choke, capacitor, inductor, ferrite core
- Voltage separation
Ferrite cores are the most popular components for EMI suppression.