TECNALIA: NUEVA DIRECTIVA EMC 2014/30/EU CAMBIOS VS 2004/108/EC. África Hernández

1. 1
EMC Solution
Generation and Suppression of
Common mode Noise
Yukio Kajita
Itaru Matsuda*
Kitagawa Industries Co., Ltd.
http://www.kitagawa.de/
http://www.kitagawa-ind.com/

2. 2
Electromagnetic Environment
Electronics life is filled with EM energy.
InterferenceMalfunction
Transmitter /Receptor

3. 3
1. Signal Wave
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
Signal wave
at 10MHz
Signal (square) wave consists of many harmonic frequency elements.
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
1 次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
1 次高調波1 次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
3 次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
3 次高調波3 次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
5 次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
5 次高調波5 次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
13次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
13次高調波13次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
99次高調波
-4 -3 -2 -1 O 1 2 3 4
-4
-3
-2
-1
1
2
3
4
x
y
99次高調波99次高調波
Convert from
time domain to
frequency domain.

4. 4
T
A
Pw
tr
Amplitude
Time
Higher rising time of pulse wave shape makes higher frequency harmonics.
Lower rising time.
Smaller amplitude.
Lower frequency.
【Pulse wave
shape】
【Spectrum】
EMC friendly design
Harmonic wave inclusive of Signal wave
20dB/decade
40dB/decade
Frequency
Amplitude
T
P
A w
⋅2
wP
f
π
1
1 =
r
f
ｔπ
1
2 =
Integral multiple
harmonics are generated.
They shall be taken
into account when
components selected.

5. 5
Ringing
Time
Voltage
Frequency
Amplitude
T
P
A w
⋅2
Overshoot
Undershoot
Noise level is much
increased.
・Higher ringing frequency makes increase noise voltage.
（But it is not directly coursed radiated emission.）
→Line impedance namely characteristic impedance shall be adjusted.
Damping resistance or chip inductor is useful measures.
*Ground bounce at flank of signal is caused even number of harmonics of signal frequ
f(Frequency）
f

6. 6
≪Electromagnetic coupling≫≪Capacitive coupling≫
Cs
L1
L2
I
I’
High frequency current flows into non-existent stripline in
circuit drawing.
→ Source of EMC ploblem
I
I”
Magnetic flux
Closer lines space makes stronger capacitive coupling and electromagnetic coupling.
Stray capacity
Non-existent stripline in circuit drawing

7. 7
2. Mechanisms of
Common mode Noise

8. 8
Differential and Common modes
Reference ground
Circuit
Differential mode current
Reference ground
Stray capacity Stray capacity
Circuit
HF currentHF current
Common mode current
*Noise voltage is generated
between two lines.
*DM current flow in two wires
in opposite direction in it’s way
to and from.
Small emission level to outside.
*Noise voltage is generated
between line and reference
ground.
*CM current flow in two or more
wires in the same direction.
Large emission level to outside.

9. 9
Radiation by Noise Current
d
lfI
E
cm ××
×= −6
10257.1
Idｍ: Differential mode
current(A)
f: Frequency（Hz)
ls: Loop area（ｍ2）
d: Distance（m)
E: Electric field
strength(V/m)
Icｍ: Common mode current
（A)
f: Frequency（Hz)
l: Line length（ｍ）
d: Distance（m)
E: Electric field
strength(V/m)
Differential mode Radiation Common mode Radiation
ＩＣ
Ground plane
ＩＣｍ
Radiated
noise
ＩＣ
ＩＣ
Loop area
Ｉｄm
Radiated
noise
d
lfI
E Sdm ××
×= −
2
14
10316.1

10. 10
Radiation of
Differential vs. Common mode
DM radiation
CM radiation
CM is dominant factor of radiated emission but DM at conducted emission can not ignore.
Cable length: 10cm
Current: 1mA
Distance: 10m
60dB = 1000 times difference at 100MHz

11. 11
Generation of Common mode
2-1 Current Driven Model
Common mode current
is generated.
Common mode current
L
o
a
d
Differential mode
Ｓｉｇ
ｎａｌ
Ｒｅｔ
ｕｒｎ
Parasitic inductance
⊿ＶＧ
L
o
a
d
Stray Capacity
dt
di
LVG =∆
≪Common mode voltage≫

12. 12
Generation of Common mode
2-2 Voltage Driven Model
Capacitive coupling
Heat-sink
ＩＣ
Radiation of noise
High frequency RF current
(Floating metal)

13. 13
Generation of Common mode
2-3 Mismatch of Balancing
LSI
High speed signal
⊿ＶＧ
Common mode current is generated by mismatch of balancing which is
caused by different width of ground patterns on PC board.
The other example is between PCB trace and cable connected to the PCB.

14. 14
Generation of Common mode
2-4 Ground Bounce
When transient current at switching flows into ground inductance, C.M. is caused.
Signal
Ground Potential
dmG
dm
G ILj
dt
dI
L ω==⊿Ｖ
※ cycle wave of signal is generated double
frequency noise wave.
Even times “f” noise wave will be generated.
※Noise voltage fluctuations in a ground
plane sharing common-inductance return
from PCB.
Ground bounce
2/1

15. 15
Fundamentals
for EMI Suppression
Shielding by Low Impedance Material

16. 16
Shielding effectiveness is highly influenced by opening
direction.
Round hole is the
optimum due to no
influence of
polarization.
Larger
emission
Emission source
Slit opening
Smaller
emission
Emission
source
Slit opening
Right angle slit against emission
source is reduced shielding
effectiveness.
Enclosure Shielding vs Slit
Opening

17. 17
0
10
20
30
40
50
60
70
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
周波数（ＧＨｚ）
シールド効果（ｄＢ）
Ｓ１Ｈ Ｓ１１Ｈ
Ｓ１２Ｈ Ｓ１３Ｈ
Ｓ1Ｈ Ｓ11Ｈ Ｓ12Ｈ Ｓ13Ｈ Ｓ8Ｈ Ｓ1Ｈ Ｓ9Ｈ Ｓ10Ｈ
0
10
20
30
40
50
60
70
80
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2
周波数（ＧＨｚ）
シールド効果（ｄＢ）
Ｓ８Ｈ Ｓ１Ｈ
Ｓ９Ｈ Ｓ１０Ｈ
Width constant Profile Height constant Profile
Profile Width（ｍ
ｍ）
Height（ｍ
ｍ）
Area
（ｃｍ２）
Profile Width（ｍ
ｍ）
Height（ｍ
ｍ）
Area
（ｃｍ２）
Ｓ１Ｈ 34.0 2.0 0.7 Ｓ１１Ｈ 34.0 10 3.4
Ｓ８Ｈ 17.0 2.0 0.3 Ｓ１２Ｈ 34.0 20 6.8
Ｓ９Ｈ 50.0 2.0 1.0 Ｓ１３Ｈ 34.0 34.0 11.6
Ｓ１０Ｈ 75.0 2.0 1.5
Smaller opening length
makes larger shielding
effectiveness.
Shielding Effectiveness vs Opening
Profile
Shielding Effectiveness value by Vertical
Polarization
Shieldingeffectiveness(dB)
Shieldingeffectiveness(dB)
Frequency (GHz) Frequency (GHz)

18. Shielding Design
■ Enclosure design minimizing
opening
Soft gasket Finger gasket
Conductive gaskets
Gap shall be 1/10 of Emission
frequency.
※Contact surface
must not be painted.
Painted mating surface makes long aperture.
Radiated emission is suppressed.
※ The smaller pitch contact is required at
near field.
NG : Larger opening
Good: smaller opening
opening
Connector
Connector
opening

19. Radiation from cable
Ground plane
Ground plane
Ground plane
No grouding
Grounding with
wire
Grounding 360°
Return path with low impedance！
Emission level is
increased at some
frequency.

20. 20
Signal Decoupling from noise
by difference of propagation mode
Fundamentals
for EMI Suppression

21. 21
Filtering
Aiming at restriction of Common
mode Current propagation toward
I/O Cable, etc.
Q1: What is the difference by size or shape?
Q2: How many turns gives effectiveness?
How to apply Ferrite Cores ??

22. 22
Effective Application for Ferrite Cores
Filtering by Ferrite Clamp One Turn
Ferrite Cores works as Common mode Filter

23. 23
How to select Ferrite Cores ①
Q1: Shape Coefficient
Correlative relationship
between noise reduction
with not size but shape
factor.
Without Frame Ground
0
5
10
15
0.0 1.0 2.0 3.0 4.0
Shape factor(Se/le)
InsertionLoss(dB)
128MHz
256MHz
320MHz
528MHz
Section Area(Ｓｅ）
Magnetic path length（ｌｅ）

24. Shape Factor
● Shape factor of
cores
（1
）
（2
）
（3
）
No. Item
Low cut high μ core
Shape
factor
Average
Magnetic
path length
（mm)
Cross
section
(mm2)
(1) TRMH16-8-16E 1.70 75.4 128
(2) TRMH25-15-12E 0.96 125.6 120
(3) TRMH38-19-13E 1.38 179.0 247
Cross section area：Ａ
ｅ
Av. Magnetic path length：
Ｌｅ
Le
Ae
NL µ2
=
≪Calculation for Inductance ≫
Ｎ：Winding Number
μ：Permeability
Shape factor
Impedance property （5 turns）
≪Refference: Toroidal core
encyclopedia≫
(1)
(3)
(2)

25. 25
1 Turn to 3 Turn
Big Loss at lower frequency
But increase emission at high “f”.
Ferrite Cores 3 Turns
1 turn

26. 26
How to select Ferrite Cores ②
Q3: Stray Capacity between wires
frequency
Impedance
Lω∆
ωC
1
Zc =
Up
Down

27. How many turn is effective?
1
10
100
1000
10000
1 10 100 1000
Impedance（Ω）
Frequency (MHz)
GRFC-8 インピーダンス特性比較
1T
2T
3T
5T
Impedance is increased
by square of turns.
Stray capacity decrease
the impedance at higher
frequency.
5T
3T
2T
1T
Capacitive coupling
Impedance property

28. ● 3 kinds of
material
Impedance （5 turns）
① ② ③
No. Part No. Permeability Product
① TRMH-16-8-16E 10000 Low cut high μ type
② TRM-16-8-16E-WE 5000 Low cut core
③ GTR-16-8-16 1600 GTR core
Suitable material shall
be selected by
frequency.
①
② ③
Material

29. How to insert core onto cable.
Magnetic flux caused by differential
mode is cancelled due to different
directions. But magnetic flux by
common mode makes insertion loss.
Ferrite core Ferrite core
Both of differential and common mode
makes insertion loss. But it requires
careful attention to saturation of
magnetic flux which causes permeability
down, heat up and noise by
magnetostrictive.
● for Common mode ● for Differential mode
Cable
Signal
GND
Differential mode
Signal
GND
Common mode Differential mode
Common mode

30. 30
Measurement of Conducted Emission
Conducted
emission
50μH
0.1μF
1000Ω
1.0μF
V type LISN* / AMN
EUT
Spectrum
Analyzer
（50Ω）
Power
*Line Impedance Stabilized Network
LISN
EUT
Reference Ground
0.8m
0.4m Power
Table
Conducted emission from
power line is measured.
EUT
Radiated
emission
How to measure CE?

31. 31
Principal of CE Measurement
EUT LISN
L
N
G
Differential Mode Current （ID)
Common Mode Current (IC)
)(50
)(50
DCN
DCL
IIV
IIV
−=
+=
Measurement system
Measuring total value of ID and IC
L
N
G
It is hard to separately observe DM current and CM current.

32. 32
When ferrite core is inserted.
● Initial State
Power line: L,N,G
● L+N+G--All lines are tuned around GRFC-13.
GRFC-13 core is inserted onto power line (5 tunes).
GRFC-13: KGS product
Initial level Initial level
Nothing changed. Why?

33. 33
Observation and Analysis
LISN
● Current Flow
EUT
DM current
CM current “1”
CM Current “2”
Insertion loss is effected against CM Current “2” only.
L
N
G
Ferrite Core：(L+N+G)

34. 34
Measurement by Current Probe
（G）（L）
（L+N）（L+N+G）
● Separately Measuring by Current Probe
CM Current “2” is observed. CM Current “1” is observed.
Both of DM and CM current are observed. CM Current “1” is observed.

35. 35
Analysis by Current Probe
CM Current Measurement DM Current Measurement
Emission mode can be identified by Current Probe.
Current Probe Current Probe
CM Current
DM Current CM Current
DM CurrentL
N
L
N

36. 36
● Insertion onto L+N ● Insertion onto L and N
● Insertion onto G
EUT
LISN
L
N
G
DM Current
CM Current “1”
Back to Ferrite core insertion
Initial level Initial level
Initial line

37. 37
Suppression measure by Ferrite Core
Recommendable Ferrite material is identified by disturbance frequency.
● Characteristics Comparison between Mg-Zn and Mn-Zn
Mg-Zn Ferrite
Suppression by Mg-Zn
Mg-Zn Ferrite
Suppression by Mn-Zn
Mn-Zn Ferrite
（L）（N） （L）（N）

38. 38
Mn-Zn Mg-Zn
Suppression measure by Ferrite Core
● Materials
1
10
100
1000
0.01 0.1 1 10 100 1000
Impedance(Ω)
Frequency (MHz)
TRM-16-8-16E （ﾛｰｶｯﾄ）
TR-16-8-16 (Ni-Znコア）
Mn-Zn
Mg-Zn
Higher suppression of Mn-Zn will be obtained
under several MHz range than Mg-Zn.
Impedance vs Frequency
Suppression performance in Equipment
Initial level
Mg

39. Variation of ferrite core
MRFC TRMH TRM
RFC- *MA
GTR
F
FFPC
GRFCTRCB

40. Frequency
100kHz 1MHz 10MHz 100MHz
TRMH
TRM
F
RFC- *MA
MRFC
GRFC
FFPC

41. 41
Grounding through Low Impedance Connection
Fundamentals
for EMI Suppression

42. 42
Suppression of Common mode Current
Grounding Design with On-board contact
■ Test① PC board ＋ FG (without FG)
■ Test② PC board ＋ FG （FG connection 4Point） at points A,B,C,D
■ Test③ PC board ＋ FG （FG connection 8Point） at points
A,B,C,D,E,F,G,H
Frame ground (FG)
Testing
board
OSC Buffe
r
Grounding Point
Ａ
CB
D
E
G
F
H
OSC（25MHｚ）
Buffer
OSC
25MHｚ
10ｐF
On-board contact
Block diagram
Measurement of radiated emission

43. 43
Emission Level is improved
OSC
25MHｚ
Frame ground (FG)
Digital ground
Large suppression is obtained
by multi point FG connection.
Without FG
4 points of
FG
8 points of
FG

44. 44
3. EMC Design and Grounding
1. Grounding
It is measure to eliminate the noise source and
suppress the radiation.
2. Filtering
Suppression and Isolation of noise source
3. Shielding
Shielding barrier of noise
Front loading design
Engineering after
sample assembled
EMC technique to suppress noise

45. 45
Grounding
How to consider about Grounding
At High Frequency
•It is NOT “0V”.
•It is influenced by disturbance noise.
•It is NOT stabilized.
Common mode noise is mainly generated by
ground-related phenomena.

46. 46
４．Grounding Design
4.1 Grounding Area
to be lower inductance
[1] Smaller grounding area
(compare to signal plane)
[2] Lager grounding area
Radiated emission measurement
(Horizontal)
Surface: Signal plane
Base: Ground plane
Surface: Signal + Ground plane
Base: All ground plane
[1] Smaller GND
[2] Larger GND

47. 47
Grounding Design
4.2 Grounding Inductance
dt
di
LL
dt
di
LV MGG )( −==∆
W
d
Common mode voltage
⊿VG
Ｌ
In order to suppress ⊿VG;
•Reduction of Self inductance → Enlarge grounding area.
•Increasing of Mutual inductance → Shorten distance between lines.
LG: Self inductance
LM: Mutual inductance
dmI
dmI

48. 48
Grounding Design
4.2.1 Grounding Inductance
(Size of Grounding Area)
Width of Grounding pattern underneath the
signal line: “W” is varied 100, 50, 20, 8mm
and measured their emission level.
-10
0
10
20
30
40
50
100 1000
周波数（MHｚ）
ノイズレベルの変化（ｄB)
グランド幅W=3mm
グランド幅W=20ｍｍ
グランド幅W=50ｍｍ
Smaller width: larger self inductance cause larger emission level.
Width：W(mm)
Signal
GND
Reference: W=100mm
W= 8mm
W=20mm
W=50mm

49. 49
Grounding Design
4.2.2 Mutual Inductance
0
5
10
15
20
25
100 1000
周波数(MHz)
ノイズの増加量（ｄB)
線間距離ｄ＝50ｍｍ
線間距離ｄ＝30ｍｍ
線間距離ｄ＝10ｍｍ
The larger distance between signal line and ground pattern causes
the smaller mutual inductance and then the larger emission level.
Distance from signal line to ground
pattern: “d” is varied 1, 10, 30, 50mm and
their emission level are measured.
*d=1mm means normal thickness of Printed
Circuit Board when ground pattern is
located under-beneath signal line.
Distance：ｄ
（mm)Signal
GND
Width：10ｍｍ
Reference: d=1mm
d=50mm
d=30mm
d=10mm

50. 50
Grounding Design
4.3 Current Driven Model & Return Path
Signal current
Return current
Separate return path results increasing GND inductance.
Return current
Return current
Signal current
Power plane
ＧＮＤ plane
GND plane
Increase GND inductance.
dt
di
LL
dt
di
LV MGG )( −==∆
【Split aperture in GND plane】 【Signal jumps over V-G
planes】
Pattern design with self and mutual inductance control is necessary.
Noise suppression by Ｃｕｒｒｅｎｔ Ｄｒｉｖｅｎ
Ｍｏｄｅｌ.
Reduce Increase

51. 51
Grounding Design
4.4 Multi point connection to Ground
It is necessary to make multi point grounding to GND plane.
※Unbalanced GND potential is not accepted.
GND plane
Signal/GND plane
Signal/GND plane
Power/GND plane
Ｉ
Ｃ
Ｉ
Ｃ
GND Via
λ/20
To be enlarged ground area.

52. 52
Grounding Design
4.5 Voltage Driven Model
※ Unstabilised grounding cause the larger
emission.
CLKIC
PC board
Metal plate
Bonding metal plate to
PC board ground is
effective for
suppression of emission
from metal plate.
Influence of emission
level between floating
metal and bonding
metal plate to the
ground.

53. 53
Voltage Driven Model
Floating metal plate placed above PC
board
1 point GND
4 points GND
8 points GND
Influence from floating metal plate
above PCB
Noise increased
Emission from PC board
Noise reduced
Noise reduced greatly
Voltage Driven Model

54. 54
Grounding Design
4.6 Uniform Balance = uniform ground
potential
Multi point grounding is
required at higher
frequency.
Frame ground
Printed circuit
board
PCB GND is to be connected
at low impedance to frame
or metal enclosure.
PCB ＧＮＤ＝Frame ＧＮ
Ｄ

55. 55
5. “Grounding”
with On-board contacts

56. 56
EMC Improvement by On-board contact (1)
Ground connection around high
speed IC with On-board contact.
Without on board contact
With on board contact

57. 57
EMC Improvement by On-board contact (2)
3 points GND
7 points GND
Connecting points to metal plate is varied.
※On-board contact placed on PCB.
LAN Port
AC Port
Metal plate

58. 58
OG 3pcs
OG 7 pcs Large effect at 500MHz over
Far field emission level

59. 59
Grounding + Shielding
0
5
10
15
20
25
30
35
500 1000 1500 2000 2500 3000
Frequency (MHz)
Suppression(dB)
① Soldered all ④ OGCP mounted 8 pcs
② Soldered 8 points ⑤ OGCP mounted 4 pcs
③ Soldered 4 points
Shielding can is
placed onto printed
circuit board which
is grounded by on-
board clip “OGCP”.
Multiple grounding
“OGCP” improves
shielding
effectiveness of the
shielding can.

60. 60

61. 61
Products in Smart-phone
①
③
④
⑤
⑥
⑦
⑧
⑨
②
①
②
③
④
⑤
⑥
⑦
⑧
On-board Clamp
On-board Contact
On-board Plate
Cool Provide
REMILESS
SMARTPLY
⑨ MIC-DAMPER
On-board Clip MAGNEFILM

62. 62
Products in Flat Panel Display
①
③
④
⑤
⑥
⑦
⑧
⑨
②
①
②
③
④
⑤
⑥
⑦
⑧
On-board Contact
Ferrite Clamp
FG Spacer
MG Absorption Sheet
Cool Provide
Fan Holder
Anti-dust Bush
Re-use Clamp
⑨
⑩
AC Cord Clamp
Shielding Gasket
⑩

63. 63
Products in Air-conditioner
①
③
④
⑤
⑥
⑦②
①
②
③
④
⑤
⑥
⑦
On-board contact
Cable Tie SUPER LOCK
Ferrite Core
COOL PROVIDE
Shielding Gasket
PCB Spacer
⑧
⑨
LOSTOMER
Heat Resistant
Cable Clamp
⑧
⑨

64. Markets & Applications ③
• Automotive electronics
June 2013 ©KITAGAWA INDUSTRIES CORPORATION. ALL
rights reserved.
64

65. Markets & Applications ④
• HEMS，SMART GRID
June 2013 ©KITAGAWA INDUSTRIES CORPORATION. ALL
rights reserved.
65

66. TRANSPARENT CONDUCTIVE FILM WINAL
• Shielding for LCD Display
• Electrode for Solar Photovoltaic system
66

67. 67
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