Line filter

Types of line filters

• A Line Filter may be incorporated in a connector. For example:
• * An AC Line Filter may be incorporated in a modular IEC 60320 power inlet connector or Power Entry Module
• * A telephone line filter may be incorporated in a modular RJ11 connector
• A line filter may be mounted on a PCB
• An AC line filter may be a stand-alone device, chassis mounted inside the equipment
• A facility AC Line Filter is mounted inside a room or cabinet, at the point where the AC power comes in

  Characteristics of line filters

• A line filter may be used to attenuate EMI in either direction. For example:
• * Emissions: It may be used to reduce the unintentional conducted emission from the equipment, to a level sufficiently low to pass regulatory limits. For example, in switching power supplies.
• * Immunity: It may be used to reduce the level of EMI entering the equipment, to a level sufficiently low not to cause any undesired behavior. For example, in equipment used in Radio Transmitter facilities
• The attenuation of Line filters is measured in 2 areas:
• * Common Mode - attenuation to signals that appear identically on each of the wires going through the filter
• * Differential Mode - attenuation to signals that appear on just one of the lines
• For each Mode, the attenuation is characterized over the frequency spectrum, and measured in dB