EMI filters, also called EMI suppression filters or RFI filters, are electrical devices/circuits that protect against high-frequency electromagnetic noise on the signal and power lines. They are available in small surface mount devices to suit low power, supply, and signal line circuits. They also come in larger modules with higher power, ideal for AC power supplies. These devices are integrated with several components with a single device that yields a frequency-dependent opposition to current flow.
What Do EMI Filters Do?
EMI filters are attached to circuits or devices to suppress conductively transferred electromagnetic noise. These filters block excessive currents through cables by extracting them and letting the required current flow freely.
The Difference Between RFI and EMI:
Radiofrequency interference (RFI) is the noise that falls on the radio frequency spectrum within the electromagnetic frequency spectrum. Meanwhile, electromagnetic interference (EMI) is any frequency of electromagnetic noise. In short, RFI is a subset of EMI and includes only electromagnetic currents.
Types of EMI/RFI Filters (LC, RC Networks):
EMI/RFI filters come in various configurations which determine the filter topology, such as:
They feature a parallel capacitor, a series resistor, or an inductor with a parallel capacitor.
They match the shape of a "T" with a series inductor or resistor, a parallel capacitor, and a series resistor or inductor.
These have a series resistor or inductor and a parallel capacitor.
Applications of EMI/RFI Filters (LC, RC Networks):
Various EMI/RFI Filters (LC, RC Networks) are applied to protect against damage from electromagnetic noise effectively. EMI filters block different noise frequencies and meet varying regulations in different environments. The following are some examples of applications of EMI filters in residential and industrial environments.
- Motor control sensors and actuators
- Audio devices
- Bluetooth, GPS, WLAN
- General Purpose
- Data lines for mobile devices
- Packaging Equipment
- LAN, PCS, WAN
- Medical-grade EMI filters
- LED Lights
- Appliances and washing machines.