Noise Suppression TechnologyNoise Suppression TechnologyNoise Suppression Technology

How to suppress NoiseHow to suppress Noise

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.

[1] Basic knowledge [1] Basic knowledge [1] Basic knowledge

Table of contentsTable of contents Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.

[2] The measure method[2] The measure method[2] The measure method

(1(1--1) 1) The concept of EMCThe concept of EMC

(1(1--2) 2) The propagation The propagation pathpath && kindkind of of noisenoise

(1(1--3) 3) The kind of conduction noiseThe kind of conduction noise

(1(1--4) 4) The kind of radiation noiseThe kind of radiation noise

(1(1--5) 5) Electrostatic Electrostatic & Electromagnetic& Electromagnetic combinationcombination

(2(2--1) I1) Importance in a product development stagemportance in a product development stage

(2(2--2) 2) A fundamental method and a procedureA fundamental method and a procedure

(2(2--3) Method 1 : Reexamination of GND arrangement3) Method 1 : Reexamination of GND arrangement

(2(2--4) Method 2 : 4) Method 2 : Use of a Use of a electromagneticelectromagnetic shieldshield

(2(2--5) Method 3 : 5) Method 3 : Use of Use of noise suppression devicesnoise suppression devices

(ex.) The noise suppression effect by (ex.) The noise suppression effect by variousvarious Noise FiltersNoise Filters

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.

[1] Basic knowledge [1] Basic knowledge [1] Basic knowledge

(1(1--1) 1) The concept of EMCThe concept of EMC

(1(1--2) 2) The propagation The propagation pathpath && kindkind of of noisenoise

(1(1--3) 3) The kind of conduction noiseThe kind of conduction noise

(1(1--4) 4) The kind of radiation noiseThe kind of radiation noise

(1(1--5) 5) Electrostatic Electrostatic & Electromagnetic& Electromagnetic combinationcombination

Electromagnetic

Compatibility

EMCEMC

EMIEMI

EMSEMS

Noise generating factor

Electromagnetic

Interference

Electromagnetic

Susceptibility

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[1] Basic knowledge [1] Basic knowledge [1] Basic knowledge

(1(1--1) 1) The concept of EMCThe concept of EMC

EmissionEmission

ImmunityImmunityNoise

Noise

conduction

radiation

conduction

radiation

Inner factor

External factor

: Harmonic wave, Ringing, Mismatching reflection, Oscillation, Switching, etc.

: Surge, Electrostatic discharge, Voltage change, Harmonic distortion, etc.

< Example >

Noise propagation pathNoise propagation path

: Radio wave,

Electrostatic & Electromagnetic combination

The kind of noiseThe kind of noise

Noise generating

equip. or circuit

Noise receiving

equip. or circuit

A

D C

B

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[1] Basic knowledge [1] Basic knowledge [1] Basic knowledge

(1(1--2) 2) The propagation The propagation PathPath && kindkind of of noisenoise

CConductiononduction

noisenoise

RRadiationadiation

noisenoise

Electrostatic

combination noise

Electromagnetic

combination noise

Emission noise

Differential mode

Common mode

Normal mode noise

Common mode noise

A

B

C

D

Propagation path

Conductor

Air

Conductor Air

ConductorAir

: Cable, Circuit patternConductor

Air

Noise current occurs in the same

course as Power or Signal sources

current.

Circuit

Vn

Ground

Noise

source

electronic equip.

Noise current

Ground

Vn

stray cap.

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[1] Basic knowledge [1] Basic knowledge [1] Basic knowledge

(1(1--3) 3) The kind of conduction noiseThe kind of conduction noise

Normal mode noiseNormal mode noise Common mode noiseCommon mode noise

electronic equip.

CircuitPower or

Signal

source

Power or

Signal

source Noise

source

stray cap.

Noise current

Noise current occurs between loop-

line and the ground.

(1(1--4) 4) The kind of radiation noiseThe kind of radiation noise

Electrical intensity (Ed)

Ed = Kd * ( ( A * ld * f2 ) / d ) [V/m]

l < ( / 10 ) , ( / 2pid )

attention

Vi Rl Vn

Cs

VnVi Rl

Cs

Signal or

Noise

source

Vn = 2pipipipif Cs Rl Vi Vn = 2pipipipif Lm Rl ln

Vi Rl Vn

magnetic flux

ln

VnVi Rl

Lm

ln

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[1] Basic knowledge [1] Basic knowledge [1] Basic knowledge

(1(1--5) 5) Electrostatic Electrostatic & Electromagnetic& Electromagnetic combinationcombination

ElectrostaticElectrostatic combinationcombination noisenoise Electromagnetic Electromagnetic combinationcombination noisenoise

Signal or

Noise

source

Usually, electrostatic combination and electromagnetic combination lives together.

Keep in mind that a cross talk increases so that load impedance (Rl) is so large that the distance between 2 lines is near.

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.

[2] The measure method[2] The measure method[2] The measure method

(2(2--1) I1) Importance in a product development stagemportance in a product development stage

(2(2--2) 2) A fundamental method and a procedureA fundamental method and a procedure

(2(2--3) Method 1 : Reexamination of GND arrangement3) Method 1 : Reexamination of GND arrangement

(2(2--4) Method 2 : 4) Method 2 : Use of a Use of a electromagneticelectromagnetic shieldshield

(2(2--5) Method 3 : 5) Method 3 : Use of Use of noise suppression devicesnoise suppression devices

(ex.) The noise suppression effect by (ex.) The noise suppression effect by variousvarious Noise FiltersNoise Filters

Measure cost

Design flexibilityLarge

Small

develop

ment

design

ing

trial

productionmass

production

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[2] The measure method[2] The measure method[2] The measure method

(2(2--1) I1) Importance in a product development stagemportance in a product development stage

Relation between measure cost and design flexibilityRelation between measure cost and design flexibility for Noise reductionfor Noise reduction

Stage

Achievement of the optimal cost performance is expectable by

performing measure sufficient in a development stage.

[1] Subject recognition to regulation[1] Subject recognition to regulation

Suppression of noise generating

Suppression of noise propagation

Measurement of a noise levelMeasurement of a noise levelMeasurement of a noise level

Investigation of a noise generation

source and a propagation course

Investigation of a noise generation Investigation of a noise generation

source and a propagation coursesource and a propagation course

Implementation of

a noise suppression

Implementation ofImplementation of

a a noise suppressionnoise suppression

The check of an effectThe check of an effectThe check of an effect

The check of operation of equip.The check of operation of The check of operation of equip.equip.

(development stage)

ProcedureProcedure

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[2] The measure method[2] The measure method[2] The measure method

(2(2--2) 2) A fundamental method and a procedureA fundamental method and a procedure

Fundamental methodFundamental method

[2] The measure method[2] The measure method

(1) Reexamination of GND arrangement(1) Reexamination of GND arrangement

(2) (2) Use of a Use of a electromagneticelectromagnetic shieldshield

(3) (3) Use of Use of noise suppression devicesnoise suppression devices

Step

1

Step

2

Step

3

Step

4

Step

5

Relation between GND intensityRelation between GND intensity

and a noise leveland a noise level

Single-sided

board

[1] Single-sided board

GND

GND is extended.

E

m

i

s

s

i

o

n

n

o

i

s

e

l

e

v

e

l

[

D

b

u

V

/

m

]

Frequency (MHz)

WeakStrong

: Double-sided board

: Single-sided board

IC IC

Vcc

GND

PCB

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[2] The measure method[2] The measure method[2] The measure method

(2(2--3) 3) Method 1Method 1 : Reexamination of GND arrangement: Reexamination of GND arrangement

[2] Double-sided board

[3] Multilayer board

The whole back surface is GND.

The inner layer is GND.

GND intensity

Weak

Strong

Test condition

A electromagnetic shield absorbs and reflects a radiation noise.

When a slit is in a shield, be careful of the following contents.

>>> The length of a slit becomes a slot-antenna to the frequency

of the wavelength used as the integral multiple of /4.

Reflection, Absorption

Filter

ShieldShield

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[2] The measure method[2] The measure method[2] The measure method

(2(2--4) 4) Method 2Method 2 : : Use of a Use of a electromagneticelectromagnetic shieldshield

Noise generating

equip. or circuit

Noise receiving

equip. or circuit

Reflection, Absorption

EMI Filter

Inductors, Bead core

Capacitor

RC-networks, LC/LR-filter

Multilayer Varistor

ZNR Transient/Surge Absorber

Line Filter

Common mode noise filter

1. Suppression by frequency ~ Harmonic noise suppression

2. Suppression by noise mode ~ Common mode noise suppression

3. Suppression by electricpotential ~ ESD & Surge noise Suppression

V

o

l

t

a

g

e

Time

V

o

l

t

a

g

e

Time

VB

V

o

l

t

a

g

e

Frequency

Noise areaSignal area

V

o

l

t

a

g

e

Frequency

Noise areaSignal area

Flux by Load current

Flux by Common mode current

load

Normal mode noise current

Load current

Common mode noise current

Load current

Load

Flux by Load current

Flux by Normal mode current

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[2] The measure method[2] The measure method[2] The measure method

(2(2--5) 5) Method 3Method 3 : : Use of Use of noise suppression devicesnoise suppression devices

Comparison of the effect by various devicesComparison of the effect by various devices

Panasonic Electronic Devices Co., Ltd.Panasonic Electronic Devices Co., Ltd.[2] The measure method[2] The measure method[2] The measure method

(ex.) The noise suppression effect by (ex.) The noise suppression effect by variousvarious Noise FiltersNoise Filters

N

o

i

s

e

l

e

v

e

l

(

d

B

u

V

)

Frequency (MHz)

Not use

(1) Bead core

(2) 3-Terminal Capacitor

(3) EMI Filters

~ 2Beads + 1Capacitor

(4) EMI Filters

~ 2Coils + 1Capacitor

The measure effect changes with devices.

Therefore, please check a noise level and select an effective device.