Custom Suppression EMI Filter
EMI filters (Electromagnetic Interference), also known as RFI filters (Radio Frequency Interference), are vital passive electronic components. Filters in general, as the name implies, are used to “filter” out the unwanted frequencies in an electronic circuit.
EMI filters are used more specifically to suppress the electromagnetic interference, which is essentially just a high frequency noise. This noise is an undesired emission that can cause the malfunctioning of a circuit or equipment. These types of EMI/RFI (interference) can be found in power supplies, microprocessors, and AC motors. This interference can be generated inside an electrical device by impedance and voltage variances in the conductors. It can also be generated outside the device via telephone lines and power cords, just to name just a few.
EMI filters can be further categorized as “Low Pass” filters. This means that they block out the high, and in this case, unwanted electromagnetic frequencies and allow only the lower frequencies to pass through.
Two of the most important components of an EMI filter are inductors and capacitors. They are critical in the reduction of the interferences that are being suppressed. The capacitors that are used are referred to as shunting capacitors because they feed the current in a specific range into the inductors that reduce the voltage as the pass through.
The EMI filter reduces the EMI or RFI by restricting the flow of high frequency signals thereby attenuating the unwanted signal strength. Without these critical components certain circuits wound be unable to function properly, making EMI/RFI filters a vital part of many electronic circuits.