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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mailto:[email protected]

Date 2018 | Technical Academy | Public Use | Topic : Radiated Emission

© All rights reserved by Wurth Electronics, also in the event of industrial property rights. All rights of disposal such as copying and redistribution rights with us. www.we-online.com

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

2

Table of content

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3

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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4

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



5

CISPR22 CE ( Quasi Peak )

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6

CISPR22 CE ( Average )

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7

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



8

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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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



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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Video Integration/EMC_xvid.avi



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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Thank you for you

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Radiated Emission Case Study - Rohde & Schwarz

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