RFI filters

RFI filter Overview

Radio frequency interference (RFI) is the noise or unwanted signal along the received or dent information. To get rid of such interference RFI filters are used. RFI filter is tuned according to the desired frequency. In other words every signal is end at a known frequency. So this frequency is given to the RFI filter. And for instance if the signal entered the RFI filter increases the particular frequency, then the increased frequency is stopped or in other words filtered out by the RFI filter.

RFI filter Components

RFI filters are composed mainly on two components. One is the Inductor and other is the capacitor. Inductors are connected in series. Capacitors work in parallel. For a circuit to protect it from a high frequency noise Inductors serve as load bearer and capacitors serve as non-load bearer. This action creates lower impedance path around the circuit offering the desired results. RFI filters are commonly available as modules or standalone devices. But you can also find PCB (Printed Circuit Board) or integrated circuits.

RFI filter Types

RFI filters are categorized as DC, single phase, and three-phase. These are the basic types further you have to chose from high pass filters, low pass filters, band pass filters, band stop filters, and many more. It depends upon the required application.

RFI performance specifications

Performance of an RFI filter depends mainly on three factors. These include insertion loss, rated current, and rated voltage. Rated voltage and current refer to the maximum amount of current and voltage a particular filter is designed for. Operating temperature is also important to consider for a particular environment.

Insertion Loss

Insertion loss is the amount of signal attenuated when the RFI filter is placed in the source and destination path. It is calculated as the ratio of the amount of noise without filter to the amount of noise with filter placed. It is measured in dB (Decibels).

RFI filter Certifications

The developers of RFI filters have to obtain certifications or approvals for their products. Certification authorities include UL (Underwriters Laboratories) Inc. Listing, UL recognized component mark, CSA mark, mil spec, and VDE (Verband Deutscher Electrotechniker) component mark. RFI filters available with CSA mark alone refers that the RFI filter can only be used in Canada. And if you find NRTL / C or C & US marks, then the RFI filter is legal for both the United Sates and Canadian markets. UL listings refer to the standards published by the Underwriter’s Laboratories Inc. It means that RFI filters must be according to these standards. Mil Spec based RFI filters must follow specifications offered by mil Spec standards.