Radiated Emission Case Study - Rohde & Schwarz
Transcript of Radiated Emission Case Study - Rohde & Schwarz
Radiated Emission Case Study
Wurth Electronics Singapore Pte Ltd
Speaker: Richard Liow
Region: SEA
E-mail: [email protected]
Phone No: +65 91763250
Date: 18 May 2018
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Date 2018 | Technical Academy | Public Use | Topic : Radiated Emission
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1. Commonly use standard
2. EMI classification
3. Radiated Emission testing
4. RE test result
5. EMI suppression table
6. Insertion loss definition
7. System impedance assumption
8. Nomogram
9. Recognizing the coupling mode
10. Transmission Modes
11. Determine type of noise
12. Select the right part for the noise
13. Design your own filter
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Table of content
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Commonly use standard
CISPR* 22
– Special International Committee on Radio Interference
– Non regulatory agency, but CISPR has adopted
• 150kHz to 30MHz Conducted
• 30MHz to 6GHz Radiated
FCC** 15
– Regulatory agency
• 450kHz to 30MHz Conducted
• 30MHz to 40GHz Radiated 5th harmonic of the highest frequency or 40GHz
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CISPR22 CE Limit
CISPR 22 Class A Conducted EMI Limit (Industrial)
Frequency of Emission (MHz) Conducted Limit (dBµV)
Quasi-peak Average
0.15 - 0.50 79 66
0.50 - 30.0 73 60
CISPR 22 Class B Conducted EMI Limit (Residential)
Frequency of Emission (MHz) Conducted Limit (dBµV)
Quasi-peak Average
0.15 - 0.50 66 to 56 56 to 46
0.50 - 5.00 56 46
5.00 - 30.0 60 50COMPANY RESTRICTED
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CISPR22 CE ( Quasi Peak )
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CISPR22 CE ( Average )
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CISPR22 RE Limit
CISPR 22 Class A 10-Metre Radiated EMI Limit
Frequency of Emission (MHz) Field Strength Limit (dBµV/m)
30 - 88 39
88 - 216 43.5
216 - 960 46.5
above 960 49.5
CISPR 22 Class B 3-Metre Radiated EMI Limit
Frequency of Emission (MHz) Field Strength Limit (dBµV/m)
30 - 88 40
88 - 216 43.5
216 - 960 46
above 960 54COMPANY RESTRICTED
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CISPR22 RE
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Conducted
(On cable)
Electromagnetic Compatibility
Emission Immunity
Conducted Radiated Conducted Radiated
Radiated (on air)
EMC CLASSIFICATION
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Product should be
tested in the EMC lab
Radiated Emission Testing
Radiated
through air
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Radiated Emission Test Result
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Radiated Emission Test Result
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EMI
Suppression
20MHz
to
300MHz
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Radiated Emission Test Result
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• Impedance
BA
BFA
ZZ
ZZZA
log20• System attenuation
BABA
A
FZZZZZ
2010
)(dBin
)(in
Insertion Loss – Definition
+
- U1 U2 ZB
ZFZA
U0
Source Coupling way Load
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System Impedance Assumption
Application overview
Assumed Practical
system impedanceApplication
1Ω GDN ( Ground Planes )
10Ω Vcc ( Supply Voltage Lines )
50Ω - 90Ω Datasignal Lines / Clock /
Video Signal / USB
90Ω - 150Ω Long Data Signal LinesCOMPANY RESTRICTED
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Nomogram
40Ω
13
17
600Ω
50
30
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Common mode noise?
Differential mode noise?
Recognizing the coupling mode
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Live (Positive)
Earth (Ground)
Recognize the transmission mode:
Differential Mode
noise or signals on a
line(s) with a return path
Common Mode
noise on all lines propagating
in the same direction with
respect to earth
Neutral (Return)
Cs
Against Differential Mode Noise
Use a differential Ferrite or choke
Against Common Mode Noise
Use a Common mode Choke
Transmission Modes
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Take a Snap Ferrite and fix it on the cable
(both lines e.g. VCC and GND)
if noise is reduced or
noise immunity increase
you have common mode interference
If not
you have differential mode interference
e.g. Common mode choke
e.g. chip bead ferrite
Determine type of noise
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Select the right part for the noise
Common mode choke Differential mode choke
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Design your own filter
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