EMC_EMI Consideration for electronic products design

12/31/2002

EMC Lab/NSYSU12006/3/8EMC Lab. NTUEE1EMC/EMI Consideration for

Electronic Products Design

Prof. Tzong-Lin Wu

2006/3/8EMC Lab. NTUEE2Introduction

zThe trends of electronic products

zHigh-speed (High frequency)

zLow voltage (Low power)

zLight weight

zEMC considerations and knowledgeare

becoming important for designing good

qualityand high stabilityelectronic products.

12/31/2002

EMC Lab/NSYSU22006/3/8EMC Lab. NTUEE3What is EMC ?

zElectromagnetic Compatibility (EMC)

zLow Electromagnetic Interference (EMI)

zHigh Electromagnetic Susceptibility (EMS)

zGood Signal Quality/Integrity (SI)

2006/3/8EMC Lab. NTUEE4How to achieve good EMC ?

•Simulation ?

•Experiment ?

•Knowledge and experience ?

12/31/2002

EMC Lab/NSYSU32006/3/8EMC Lab. NTUEE5How to achieve good EMC

•Suppress the emission at its source

•Make the coupling path as inefficient as possible

•Make the receptor less susceptible to the emissionSource

(Emitter)Transfer

(Coupling)

PathReceptor

(Receiver)

Cost: Lowmiddlehigh

2006/3/8EMC Lab. NTUEE6zAn example: for PC

zSuppress the emission:

zProper layout with EM concept

zusing component with low edge rate as possible

zReduce coupling path

zusing shielded enclosure

zIsolation

zless susceptible receptor

zdifferential pairs

zerror-correcting codeHow to achieve good EMC

12/31/2002

EMC Lab/NSYSU42006/3/8EMC Lab. NTUEE7Case study I : Notebook EMI

LCD Panel

Notebook•Flexible Printed Circuits (FPC)

2006/3/8EMC Lab. NTUEE8Fully Anechoic Chamber

EMI Measurement Environment in Our University

12/31/2002

EMC Lab/NSYSU52006/3/8EMC Lab. NTUEE9Case study I

The EMI measurement(300MHz~1000MHz)

2006/3/8EMC Lab. NTUEE10Case study I

The EMI measurement(30MHz~300MHz)

Why ?

How to solve ?

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EMC Lab/NSYSU62006/3/8EMC Lab. NTUEE11Case study I

Where is the radiation source ?

FPC

PCTFT-LCD

disconnect

2006/3/8EMC Lab. NTUEE12Case study I

󰋃󰋈󰋄󰋃󰋄󰋈󰋅󰋃󰋅󰋈󰋆󰋃󰋆󰋈󰋇󰋃󰋇󰋈󰋈󰋃

󰋄󰋅󰋆󰋇󰋷󰋕󰌈󰋩󰋂󰌀󰋢󰌅󰋼󰋺󰋼󰌁󰋴󰋿

󰌆󰌂󰋿󰋼󰋷󰋀󰌆󰌂󰋿󰋼󰋷

󰋺󰌁󰋷󰋀󰌀󰋸󰌆󰋻

󰌀󰋸󰌆󰋻󰋀󰌀󰋸󰌆󰋻

󰌀󰌂󰋴󰌇

󰘥󰵄(󰳡

󰫿󰎱󰘥󰵄(󰪹

󰫿󰎱LCD-FPC不󰵷

(󰳡󰫿󰎱LCD-FPC不

󰵷(󰪹󰫿󰎱

12/31/2002

EMC Lab/NSYSU72006/3/8EMC Lab. NTUEE13Case Study I

FPC

PCTFT-LCDWhat is the radiator ?

Disconnect

2006/3/8EMC Lab. NTUEE14Case Study I

FPC is the radiator ?

12/31/2002

EMC Lab/NSYSU82006/3/8EMC Lab. NTUEE15Case Study I

FPC

PCTFT-LCD

Spectrum

AnalyzerCommon-mode current Probe:

Significant common-mode current is

measured at 193MHz !!

Can we verify our assumption by theoretical approach?󰻢󰛯󰎚dBµA󰘥󰵄LCD-FPC不󰵷

Original16.6320.29

Solid-solid8.892.69

Ground-mesh9.1418

2006/3/8EMC Lab. NTUEE16Case study I: common-mode radiation

()θβ

θF

re

IME

irj

iii0ˆˆˆ

,−

=

()

()()

()

()θθθ

βββββββ

θ

FeIeI

re

MF

re

I

re

IMF

re

I

re

IME

jjjrjrjrjrj

)ˆˆ(ˆ)ˆˆ(ˆ)ˆˆ(ˆˆ

000002010

212122

11

∆∆−−∆−−∆+−−−

+=∆−+

∆+=+=Mˆis a function of the antenna type

()θFis the antenna pattern

12/31/2002

EMC Lab/NSYSU92006/3/8EMC Lab. NTUEE17The Common-mode radiation

CC

IIII

ˆˆˆˆ

21

==

{}

227

max,000ˆ

102ˆsjsjdjC

Ceee

dLIf

jEβββπ+×=−−−

dfLI

EC

Cˆ

10257.1ˆ6

max,−×=

The Differential-mode radiation

DD

IIII

ˆˆˆˆ

21

−==

{}

227

max,000ˆ

102ˆsjsjdjD

Deee

dLIf

jEβββπ−×=−−−

dLfI

ED

D2

14

max,ˆ

10316.1ˆ−×=Case study I: common-mode radiation

2006/3/8EMC Lab. NTUEE18Case study I: common-mode radiation

󰋃󰋈󰋄󰋃󰋄󰋈󰋅󰋃󰋅󰋈󰋆󰋃󰋆󰋈󰋇󰋃

󰋄󰋅󰋆󰋷󰋕󰌈󰋩󰋂󰌀󰋠󰋸󰋴󰌆󰌈󰌅󰋸󰌀󰋸󰌁󰌇

󰋖󰋴󰋿󰋶󰌈󰋿󰋴󰌇󰋼󰌂󰌁

OriginalSolid-solidGround-mesh󰘥󰵄(󰳡󰫿)Comparison between theory and measurement

Agreement is good !󰋃󰋈󰋄󰋃󰋄󰋈󰋅󰋃󰋅󰋈󰋆󰋃󰋆󰋈󰋇󰋃

󰋄󰋅󰋆󰋷󰋕󰌈󰋩󰋂󰌀󰋠󰋸󰋴󰌆󰌈󰌅󰋸󰌀󰋸󰌁󰌇

󰋖󰋴󰋿󰋶󰌈󰋿󰋴󰌇󰋼󰌂󰌁LCD-FPC不󰵷(󰳡󰫿)

OriginalSolid-solidGround-mesh

12/31/2002

EMC Lab/NSYSU102006/3/8EMC Lab. NTUEE19Case study I

zSummary for the Notebook EMI problem

zSource:3rd harmonic of 64MHz of LVDS signals

zRadiation:Common-mode current radiation via

FPC

zHow to solve that ? Think about it !

2006/3/8EMC Lab. NTUEE20Case Study I : Solving approach

CuCu

dielectricdielectricsignal line