EMI Components

R,L,C Component TDR response

: A.Board band (switch)switching noise , : 1. 2.

B. (Clock Narrow Band) 01, (less then 40 times) ,

Current Typical EMI Noise suppressor Characteristic

(By Pass),,

:

TDR(BY PASS ),,,

Current Typical EMI Noise suppressor CharacteristicBy Pass Capacitor Noise Filtering Characteristic

PCB

EMI Components Notch Curve Measurement

Test Equipment: Agilent 5070B Network AnalyzerMeasurement Frequency Band: 300KHz to 3GHz

10PF By Pass Capacitor Attenuation CurveNotch Band: 1.7GHz to 2.8GHzNotch Point: 2.1GHz (-39dB)

100PF By Pass Capacitor Attenuation Curve

Notch Band: 748MHz to 1.5GHzNotch Point: 1.1GHz (-43dB)

100pF

1000PF By Pass Capacitor Attenuation CurveNotch Band: 73MHz to 600MHzNotch Point: 209MHz (-38dB)

1000pF

10000PF By Pass Capacitor Attenuation Curve

Notch Band: 300KHz to 956MHzNotch Point: 28MHz (-58dB)

10000pF

Capacitance VS. Notch Curve

10000pF Notch Curve2.1GHz(-39dB)

1000pF Notch Curve1.1GHz(-43dB)

100pF Notch Curve209MHz(-38dB)

10pF Notch Curve28MHz(-58dB)

De Cap. Impedance Feature

0.001

0.01

0.1

1

10

100

0.1 1 10 100 1000 10000

100uF

10uF

1uF

100nF

10nF

1nF

100pF

10pF

1pF

Impe

danc

e (o

hm)

Frequency (MHz)

Choosing a De-Cap

Montrose, EMC and the Printed Circuit Board, Wiley, 1999

Current Typical EMI Noise suppressor CharacteristicBy Pass Capacitor Noise Filtering Characteristic

,,,,,.

Current Typical EMI Noise suppressor CharacteristicBy Pass Capacitor Noise Filtering Characteristic

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

, EMI(ferrite bead),

,,(ferrite bead), ,

(ferrite bead)? ,EMI?

(ferrite),EMI

Ferrite Bead Noise Transfer Theory

Signal Current Ferrite Bead

FR4 PCB

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

:

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

PCB

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

,-20dB300Ferrite Bead 121.57MHz -13.97dB

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

,-20dB600Ferrite Bead 89.42MHz -18.4dB,Notch Point 89.42MHz 100MHz

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

,-20dB3000Ferrite Bead 58.08MHz -25.7dB,25.12 to 118.36MHz 100MHz

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

,-20dB240Ferrite Bead 1GHz -10.23dB

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

,-20dB3A/600Ferrite Bead 1GHz -5.9dB

Current Typical EMI Noise suppressor CharacteristicFerrite Bead Noise Filtering Characteristic

ferrite beadsbead,,,EMI,EMI,EMI,,

Bead Notch Curve Band

300OhmBead + 1uF By Pass Cap. LC Notch Curve Band

600Ohm Bead + 1uF By Pass Cap. LC Notch Curve Band

1500Ohm Bead + 1uF By Pass Cap. LC Notch Curve Band

300Ohm Bead + 1uF By Pass Cap. T Type Notch Curve Band

600Ohm Bead + 1uF By Pass Cap. T Type Notch Curve Band

1500Ohm Bead + 1uF By Pass Cap. T Type Notch Curve Band

300Ohm Bead + 1uF By Pass Cap. Type Notch Curve Band

600Ohm Bead + 1uF By Pass Cap. Type Notch Curve Band

1500Ohm Bead + 1uF By Pass Cap. Type Notch Curve Band

Construction Of MultiConstruction Of Multi--Layer Chip BeadLayer Chip Bead

XX--Ray View of MultiRay View of Multi--layer Chip Bead layer Chip Bead

X Ray View of Chip Inductor

10uH Inductor Notch Band

10uH Inductor + 1uF By Pass Cap. LC Notch Curve Band

10uH Inductor + 1uF By Pass Cap. T Type Notch Curve Band

10uH Inductor + 1uF By Pass Cap. Type Notch Curve Band

Bead

Bead()

100MHz

BeadEMI

Bead()(H)

Equivalent circuitEquivalent circuit

Common mode current Common mode current (Noise)(Noise)

Differential mode currentDifferential mode current(Signal)(Signal)

Opposite directionOpposite directionMagnetic flux canceledNo impedance No impedance produced to signal

Same directionSame directionMagnetic flux addedProducing impedance Producing impedance to noiseto noise

How do the Common Mode Filters suppress noise?How do the Common Mode Filters suppress noise?

Differential TransmissionDifferential Transmission

There is separate return path There is separate return path other than ground lineother than ground line

ItIts called s called Balanced TransmissionBalanced Transmission

Conventional Transmission Conventional Transmission Return path is ground lineReturn path is ground line

ground line

ground line

Transmission of signalsTransmission of signals

Two beads are usedTwo beads are used

Input waveform

(Before filtering)Output waveform

(After filtering)

Large distortionLarge distortion

One CMF is usedOne CMF is used

Input waveform

(Before filtering)

Output waveform

(After filtering)

Small distortionSmall distortion

Ferrite beads can cause waveform distortionFerrite beads can cause waveform distortion

No FiltersNo Filters Used CMFUsed CMF Used Ferrite BeadsUsed Ferrite Beads

Evaluation of radiated noiseEvaluation of radiated noise

a

b

a ~ ba ~ b

Strong for external noiseStrong for external noise

Signals are detected by subtracting the current of 2 linesSignals are detected by subtracting the current of 2 lines

Features of differential transmissionFeatures of differential transmission

idealideal

out of phaseout of phase voltage differencevoltage difference

Unbalanced component of signalUnbalanced component of signal

Collapsed balancing becomes noiseCollapsed balancing becomes noise

Common mode noiseCommon mode noise(Unbalanced component of signal)

Differential signal with collapsed balanceDifferential signal with collapsed balance

Reference ground surface

Collapsed balancing becomes noiseCollapsed balancing becomes noise

No skew is present.No skew is present.

Skew is present.Skew is present.Using no CMFUsing no CMF

No skew is present.No skew is present.Using CMFUsing CMF

Selection of EMC ComponentsSelection of EMC Components

Resistor

LC Filter

Common mode filter

Bead

n

Beads vs. CMFBeads vs. CMF

Example for USB

Common Mode : 600 @100MHzDifferential Mode : 40 @240MHz

Common Mode : 90 @100MHz

Differential Mode : 18 @240MHz

Chip Beads100 @100MHz

Initial

No skew is present.

Noise reductionMethod

LPF

LPF

Noise filtering method

Beads

CMF

Section

Common Mode Choke

Chip Common Mode Choke Coils Film Type DLP31S Series / Murata

Spiral Design High Coupling coefficient (~98%) High Insulation Resistance

4527

4.5

3

14 50

1M 10M 100M 1G1

10

100

1000

10000

22 Ohm

623 Ohm

Impe

danc

e [o

hm]

Frequency [Hz]

1M 10M 100M 1G0

10

20

30

40

50

60

70

80

90

100Max.98.70%100MHz

98.27%

Cou

plin

g C

oeffi

cien

t [%

]Frequency [Hz]

X X X X X X

Common Mode :

Normal Mode :

X X XX X X

TAITECH Common mode Choke Coils MCM3216C2S-900PT08

Multilayer DesignMultilayer Design Low Coupling coefficient (~70%) High Insulation Resistance High Normal Mode |Z|

1M 10M 100M 1G1

10

100

1000

36 Ohm

72 Ohm

Impe

danc

e [O

hm]

Frequency [Hz]

1M 10M 100M 1G0

10

20

30

40

50

60

70

80

90

100

Max77.67%

100MHz75.67%

Cou

plin

g C

oeffi

cien

t [%

]

Frequency [Hz]

X

X

X

Common Mode : 1,2 Major Loop

-> |Z| .

Normal Mode : 1,2 Major Loop

Minor Loop |Z| .

Minor Loop Ferrite SRF .

X

X

X

WALSIN Common mode Choke Coils RFCMF series

Process (Glass Material ) Multilayer DesignMultilayer Design Low Coupling coefficient (~70%) High Insulation Resistance High Normal Mode |Z| Low Common Mode |Z|

1M 10M 100M 1G1

10

100

1000

10000

Impe

danc

e [O

hm]

Frequency [Hz]

com1 com2 com nor

Panasonic Common mode Choke Coils ELKU series

SSpiral Designpiral Design High Coupling coefficient (~91%) High Insulation Resistance High Normal Mode |Z|

1M 10M 100M 1G1

10

100

1000

Impedance [Ohm]

Frequency [Hz]

com1 com2 com nor

Incredible wide band attenuation character 30MHz to 8GHz (over -20dB)Whole new innovate design concept

Advantages:1. Up grade system speed and stability 2. Universal EMI/EMC solution3. Short new product R&D period 4. Reduce components quantities5. Reduce spare parts and stock cost 6. Low power consumption

New UWB Noise Suppressor

UWB Noise SuppressorUWB 2500 Noise Suppressor Characteristic

,-20dB122.12MHz to 2.3GHz UWB2500

UWB Noise SuppressorUWB B2000 Noise Suppressor Characteristic

,-20dB300KHz to 3GHz UWB B2000(Clock Noise)

UWB2500 Filter + 1uF By Pass Cap. LC Notch Curve Band

UWB Filter + 1uF By Pass Cap. T Type Notch Curve Band

2500UWB Filter + 1uF By Pass Cap. Type Notch Curve Band

UWB Choke Noise Cancer Theory

Signal Current

Talking RingReverse Current

UWB Choke

UWB Choke, UWB, , ,Trace