• Latest
  • Trending
  • All
  • Capacitors
  • Resistors
  • Inductors
  • Filters
  • Fuses
  • Non-linear Passives
  • Applications
  • Integrated Passives
  • Oscillators
  • Passive Sensors
  • New Technologies
  • Aerospace & Defence
  • Automotive
  • Industrial
  • Market & Supply Chain
  • Medical
  • RF & Microwave
  • Telecommunication

Introduction to EMI Filtering

27.1.2023

Würth Elektronik Announces Virtual Conference Digital WE Days 2023

22.9.2023

Circuit Protection Selection Guide 

22.9.2023

WT Microelectronics to Acquire Future Electronics

20.9.2023

Circuit Protection Components 2023 Market Analysis

20.9.2023

Ink-Jet Printed Flexible Capacitors: Manufacturing and Ageing Tests

19.9.2023

4th PCNS Awards Passive Component Papers

19.9.2023
  • Home
  • Privacy Policy
  • EPCI Membership & Advertisement
  • About
No Result
View All Result
NEWSLETTER
Passive Components Blog
  • Home
  • NewsFilter
    • All
    • Aerospace & Defence
    • Antenna
    • Applications
    • Automotive
    • Capacitors
    • Circuit Protection Devices
    • Filters
    • Fuses
    • Inductors
    • Industrial
    • Integrated Passives
    • Market & Supply Chain
    • Medical
    • New Materials & Supply
    • New Technologies
    • Non-linear Passives
    • Oscillators
    • Passive Sensors
    • Resistors
    • RF & Microwave
    • Telecommunication

    Circuit Protection Selection Guide 

    WT Microelectronics to Acquire Future Electronics

    Circuit Protection Components 2023 Market Analysis

    Ink-Jet Printed Flexible Capacitors: Manufacturing and Ageing Tests

    4th PCNS Awards Passive Component Papers

    Benefits of Ceramic Capacitors as Bootstrap Capacitors

    Vishay Boosts Power Inductor Manufacturing Capacity in Mexico

    SUMIDA to Build New Inductive Components Factory in Northern Vietnam

    Oscillators Integration, Selection Guide and Design In

    Trending Tags

    • Ripple Current
    • RF
    • Leakage Current
    • Tantalum vs Ceramic
    • Snubber
    • Low ESR
    • Feedthrough
    • Derating
    • Dielectric Constant
    • New Products
    • Market Reports
  • VideoFilter
    • All
    • Antenna videos
    • Capacitor videos
    • Filter videos
    • Fuse videos
    • Inductor videos
    • Non-linear passives videos
    • Oscillator videos
    • Passive sensors videos
    • Resistor videos
    • Sensors

    Oscillators Integration, Selection Guide and Design In

    Input Capacitor Selection for Power Supplies – Part 3: Electrolytic Capacitors

    Input Capacitor Selection for Power Supplies Part 2 – Ceramic Capacitors

    Input Capacitor Selection for Power Supplies Video (Part 1)

    Vishay Webinar: Components Selection for Solar Panel Systems

    Capacitors Basics: Decoupling

    Totem Pole PFC Design for E-Mobility; Microchip and WE Video

    High frequency model of the physical inductor: The Cauer model

    High frequency model of the physical inductor: The basic lumped model

    Trending Tags

    • Capacitors explained
    • Inductors explained
    • Resistors explained
    • Filters explained
    • Application Video Guidelines
    • EMC
    • New Products
    • Ripple Current
    • Simulation
    • Tantalum vs Ceramic
  • Knowledge Blog
  • Suppliers
    • Preferred Suppliers
    • Who is Who
  • Events
  • Home
  • NewsFilter
    • All
    • Aerospace & Defence
    • Antenna
    • Applications
    • Automotive
    • Capacitors
    • Circuit Protection Devices
    • Filters
    • Fuses
    • Inductors
    • Industrial
    • Integrated Passives
    • Market & Supply Chain
    • Medical
    • New Materials & Supply
    • New Technologies
    • Non-linear Passives
    • Oscillators
    • Passive Sensors
    • Resistors
    • RF & Microwave
    • Telecommunication

    Circuit Protection Selection Guide 

    WT Microelectronics to Acquire Future Electronics

    Circuit Protection Components 2023 Market Analysis

    Ink-Jet Printed Flexible Capacitors: Manufacturing and Ageing Tests

    4th PCNS Awards Passive Component Papers

    Benefits of Ceramic Capacitors as Bootstrap Capacitors

    Vishay Boosts Power Inductor Manufacturing Capacity in Mexico

    SUMIDA to Build New Inductive Components Factory in Northern Vietnam

    Oscillators Integration, Selection Guide and Design In

    Trending Tags

    • Ripple Current
    • RF
    • Leakage Current
    • Tantalum vs Ceramic
    • Snubber
    • Low ESR
    • Feedthrough
    • Derating
    • Dielectric Constant
    • New Products
    • Market Reports
  • VideoFilter
    • All
    • Antenna videos
    • Capacitor videos
    • Filter videos
    • Fuse videos
    • Inductor videos
    • Non-linear passives videos
    • Oscillator videos
    • Passive sensors videos
    • Resistor videos
    • Sensors

    Oscillators Integration, Selection Guide and Design In

    Input Capacitor Selection for Power Supplies – Part 3: Electrolytic Capacitors

    Input Capacitor Selection for Power Supplies Part 2 – Ceramic Capacitors

    Input Capacitor Selection for Power Supplies Video (Part 1)

    Vishay Webinar: Components Selection for Solar Panel Systems

    Capacitors Basics: Decoupling

    Totem Pole PFC Design for E-Mobility; Microchip and WE Video

    High frequency model of the physical inductor: The Cauer model

    High frequency model of the physical inductor: The basic lumped model

    Trending Tags

    • Capacitors explained
    • Inductors explained
    • Resistors explained
    • Filters explained
    • Application Video Guidelines
    • EMC
    • New Products
    • Ripple Current
    • Simulation
    • Tantalum vs Ceramic
  • Knowledge Blog
  • Suppliers
    • Preferred Suppliers
    • Who is Who
  • Events
No Result
View All Result
Passive Components Blog
No Result
View All Result

Introduction to EMI Filtering

27.1.2023
Reading Time: 8 mins read
A A
38
VIEWS

This blog article by Knowles Precision Devices introduces EMI Filtering, EMI Filter, how it works and what is its performance.

With the ever-increasing use of electronic equipment comes a greater likelihood of interference from all the other equipment out there. In the same vein, we’re seeing more circuits, with lower power levels, that are easily disturbed; so, there’s a need to protect equipment from EMI (electromagnetic interference). In automotive or medical applications, for example, there can be no false alarms due to external interference. The level of uncertainty has pushed EMI compliance testing to the component level.

RelatedPosts

Benefits of Ceramic Capacitors as Bootstrap Capacitors

Knowles Enters into Agreement to Acquire Cornell Dubilier

Benefits of Using Ceramic Capacitors for Decoupling

To meet international legislation such as the EU Directive on EMC or the FCC, EMI filtering is an essential element of equipment design. Introducing screening measures to case or cables, for example, may suffice in many instances, but you might need to introduce low-pass filtering for additional protection as well. Here, we will begin to explore EMI filtering and the terminology used in designing effective protection.

Input / Output Cabling

Figure 1: Modes of propagation of EMI

In an ideal situation, a Faraday Cage would protect a piece of equipment or circuit from EMI by totally enclosing it in a metal (or conductive box) and preventing interference. However, most pieces of equipment require input and/or output connections for power cables or signal control lines. The cables providing these kinds of connections can act as antennae that can pick up interference and radiate it, see Figure 1.

Subsequently, the following can occur:

  • Interference can enter a piece of equipment directly through the cabling (conducted interference).
  • Radiated interference can travel directly to the affected equipment.
  • Interference can exit an EMI source via a cable, subsequently to be radiated from the cable and to the affected equipment.
  • Interference can be radiated from an EMI source and then picked up by a cable entering the affected equipment.

Filter Location

Filter Location matters when it comes to preventing interference entering or leaving a piece of equipment. With Panel Mount Filters, feedback through EMI filters can be mounted in the wall of a shielded case, see Figure 2. All incoming or outgoing cables would then pass through the filters. Power, or any other wanted signals, pass through the filters unaffected, whereas higher frequency interference is removed. The screened case protects against radiated interference, and feedthrough filters protect against conducted interference. Combined, the integrity of the equipment is assured.

Figure 2: Feedthrough filters remove conducted interference and provide ultimate performance
Figure 3: Surface mount filters remove conducted interference, performance reduced due to radiated interference

When there is no suitable bulkhead for mounting filters, Surface Mount Filters, see Figure 3, are an effective option. In general, insertion loss performance is reduced at higher frequencies, unless additional screening measures are taken. Thoughtful design practices including short tracks and connections, good grounding, and proximity to input will help improve insertion loss performance.

Common Terms

The following chart provides a foundational understanding of common terms used when designing and implementing EMI filters.

Conducted Interference Interference transmitted along a conductor/cable.Protection is provided by a series component. If a feedthrough filter is used to remove conducted interference, and mounted in the wall of a shielded compartment, it provides effective filtering while maintaining the screening integrity. It should be noted that the filter will reduce both emissions and susceptibility.
Cut-off Frequency/3dB pointThe frequency at which filters start to become effective.Generally taken to be at the 3dB point of the attenuation curve. Anything on the line below this frequency will be unaffected. The higher the capacitance of the filter the lower the cut-off, and vice versa. It will also vary depending on source and load impedances.
EMCElectromagnetic compatibility.A situation wherein two pieces of electrical or electronic equipment are able to function in the same environment without adversely affecting, or being affected by, each other.
EMIElectromagnetic interference.A broad term covering a wide range of electrical disturbances, natural and man-made, from dc to GHz frequencies and beyond. Sources of disturbance may include radar transmitters, motors, computer clocks, lightning, electrostatic discharge and many other phenomena.
Conducted EmissionsSignals, unwanted (interference) or otherwise from a piece of equipment.
Radiated InterferenceInterference transmitted in free air.Protection is provided by shielding, but if filters are not used to protect against conducted emissions, the unfiltered lines can act as aerials radiating interference outside the shielded cage.
SusceptibilityThe extent to which a piece of equipment is vulnerable to interference emitted from another piece of equipment.
ESDElectrostatic discharge.ESD can result in damage through excessive voltage spikes. We can assist on whether our products can meet specific ESD test requirements.
Insertion LossAt a given frequency, the insertion loss of a feedthrough suppression capacitor or filter connected into a given transmission system.Defined as the ratio of voltages appearing across the line immediately beyond the point of insertion, before and after insertion. As measured herein, insertion loss is represented as the ratio of input voltage required to obtain constant output voltage, with and without the component, in the specified 50Ω system. This ratio is expressed in decibels (dB) as follows:

insertion loss knowles

When testing is conducted with a network/spectrum analyzer, the equipment usually maintains a constant output voltage and can be set to record the output to input voltage ratio in decibels.
Low-Pass FilterA filter that lets through dc and low frequency signals, while attenuating (unwanted) high frequency noise.
Panel MountA panel mounted filter that will pass the signal from one side of the wall of a shielded box (or ‘Faraday Cage’) to the other (it feeds the signal through the panel).For effective operation, the filter input and output should be screened from each other, i.e. there should ideally be no apertures in the panel.
panel mounting knowles
Surface Mount FilterSurface Mount Filter A filter that is suitable for surface mounting on PCBs.It offers improved filtering compared to standard MLCCs, ease of assembly and savings on board space compared to a combination of discrete filter elements. Filter performance at higher frequencies is reduced compared to panel mount types, unless additional shielding measures are taken.
surface mount filter
Working VoltageContinuous operating voltage.This can potentially be across the entire operating temperature range.
X2Y FilterIntegrated passive component with extremely low self inductance for filtering and de-coupling.

For filtering applications: filtering applications

For de-coupling applications: de-coupling applications
Source: Knowles Precision Devices

Related Posts

Circuit Protection Devices

Circuit Protection Selection Guide 

22.9.2023
16
Capacitors

Benefits of Ceramic Capacitors as Bootstrap Capacitors

19.9.2023
43
Market & Supply Chain

Knowles Enters into Agreement to Acquire Cornell Dubilier

19.9.2023
65

Upcoming Events

Sep 26
September 26 @ 12:00 - September 28 @ 14:00 EDT

Microwave Packaging Technology

Sep 26
16:00 - 17:00 CEST

Connector Temperature Rise and Derating

Oct 3
October 3 @ 12:00 - October 5 @ 14:00 EDT

Design and Test of Non-Hermetic Microelectronic

View Calendar

Popular Posts

  • What is a Dielectric Constant of Plastic Materials ?

    4 shares
    Share 4 Tweet 0
  • Understanding High-Precision Resistor Temperature Coefficient of Resistance

    0 shares
    Share 0 Tweet 0
  • Ripple Current and its Effects on the Performance of Capacitors

    3 shares
    Share 3 Tweet 0
  • Why Low ESR Matters in Capacitor Design

    0 shares
    Share 0 Tweet 0
  • Capacitor Selection for Coupling and Decoupling Applications

    28 shares
    Share 28 Tweet 0
  • How to Choose the Right Inductor for DC-DC Buck Applications

    0 shares
    Share 0 Tweet 0
  • Non-Linear Resistors: Thermistors, Varistors, Memristors

    0 shares
    Share 0 Tweet 0
  • Leakage Current Characteristics of Capacitors

    0 shares
    Share 0 Tweet 0

Newsletter Subscription

 

Archive

2023
2022
2021
2020
2019
2018
2017

Symposium

Passive Components Networking Symposium

Passives e-Learning

Knowledge Blog

  • Home
  • Privacy Policy
  • EPCI Membership & Advertisement
  • About

© EPCI - Premium Passive Components Educational and Information Site

No Result
View All Result
  • Home
  • News
  • Video
  • Knowledge Blog
  • Preferred Suppliers
  • Events

© EPCI - Premium Passive Components Educational and Information Site

This website uses cookies. By continuing to use this website you are giving consent to cookies being used. Visit our Privacy and Cookie Policy.