Magnetics Business & Technology - Summer 2018 - 18

RESEARCH & DEVELOPMENT

Electrical Noise Suppression and
Common Mode Choke
By Rickey Cheang, FAE, IEEE Member, ITG-Electronics Inc.
Abstract -- At higher frequencies the impedance of a common
mode choke becomes an important factor to effectively suppress
EMI noise. This paper will discuss common mode noise generators and how it can be suppressed by using a common mode
choke; further discussing impedance improvements by using
different winding techniques and wire shapes that enhance the
performance and efficiency of the common mode choke.
I. INTRODUCTION
Continuous electrical humming noise can be very annoying and
may be harmful to hearing. This paper will briefly discuss the
noises, electromagnetic interference, common mode and differential mode noise and how common mode choke functions with
description and effect of a common mode filter. Further discuss
the general and inductive impedance and comparisons of different winding technique and wire shape to provide a better efficient
choice of common mode choke selection.

Electromagnetic interference (EMI) falls under the category of
electrical noise. A basic change of state (such as On/Off) in an
electronic component has the potential to generate EMI. Typical
examples are electronic switchers, clocks, electronic controls,
power suppliers, inverters, fluorescent lights, motor brushes,
etc....
The EMI noise can be either radiated through the air or conducted through the power line which includes common mode noise,
and differential mode noise. [2]
Common mode noise is a signal transferring between all the
lines in the same direction to the ground in a circuit. See Fig 2

II. NOISES AND EMI
Noise is an unwanted, loud, or confused sound which is meaningless but disruptive to hearing. There are typically two different
types of noise, acoustical noise and electrical noise.
Acoustical noise is any unwanted sound or vibration that is audible to the human ear and/or tangible via touch.
Electrical noise is by literal definition, not particularly audible or
discernible by tactile interaction with the component or equipment.
To further explain the electrical noise, it is not audible to the human ear. Even in high-end audio equipment, actual electrical
noise is not audible, but its effect on the analog audio output
is audible as distortion at many or just certain frequencies. The
noise itself requires specialized test equipment to detect, analyze, and define.[1]

Fig. 2 Common Mode Noise
Differential mode noise is a signal conducting between Line and
Neutral in the opposite direction. See Fig. 3

By standard definition, electrical noise is any unwanted variation in an electrical signal. In fact, all circuits have some inherent
electrical noise. Once again, depending on the circuit or system,
electrical noise may be acceptable within certain limits.

Fig. 3 Differential Noise Mode

Fig. 1 Noise Combination Signal

18

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Table of Contents for the Digital Edition of Magnetics Business & Technology - Summer 2018

Magnetics Business & Technology - Summer 2018
Contents
Editor’s Choice
Magnetic Nanoparticles Leap from Lab Bench to Breast Cancer Clinical Trials
Safran, a Major Player in Plasma Propulsion, Finds Booming Market for its Hall Eff ect Thrusters
NASA Develops Hall-Eff ect Electric Propulsion to Thrust Exploration on into Deep Space
Airbus-built SES-12 Dual-mission Satellite Successfully Launched
Research & Development
Case Study
Product News
Industry News
Marketplace/ Advertising Index
Spontaneous Thoughts: Dysprosium 2.0
Magnetics Business & Technology - Summer 2018 - Magnetics Business & Technology - Summer 2018
Magnetics Business & Technology - Summer 2018 - Cover2
Magnetics Business & Technology - Summer 2018 - Contents
Magnetics Business & Technology - Summer 2018 - Editor’s Choice
Magnetics Business & Technology - Summer 2018 - 5
Magnetics Business & Technology - Summer 2018 - Magnetic Nanoparticles Leap from Lab Bench to Breast Cancer Clinical Trials
Magnetics Business & Technology - Summer 2018 - 7
Magnetics Business & Technology - Summer 2018 - Safran, a Major Player in Plasma Propulsion, Finds Booming Market for its Hall Eff ect Thrusters
Magnetics Business & Technology - Summer 2018 - 9
Magnetics Business & Technology - Summer 2018 - NASA Develops Hall-Eff ect Electric Propulsion to Thrust Exploration on into Deep Space
Magnetics Business & Technology - Summer 2018 - 11
Magnetics Business & Technology - Summer 2018 - Airbus-built SES-12 Dual-mission Satellite Successfully Launched
Magnetics Business & Technology - Summer 2018 - 13
Magnetics Business & Technology - Summer 2018 - Research & Development
Magnetics Business & Technology - Summer 2018 - 15
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Magnetics Business & Technology - Summer 2018 - Case Study
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Magnetics Business & Technology - Summer 2018 - Marketplace/ Advertising Index
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Magnetics Business & Technology - Summer 2018 - Spontaneous Thoughts: Dysprosium 2.0
Magnetics Business & Technology - Summer 2018 - Cover3
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