wurth electronics inc. field application engineer michael

Würth Elektronik eiSos © May/2006 Michael Eckert

Welcome!Inductors & EMC-Ferrites

Basics Basics -- Parts and Parts and ApplicationsApplications

Wurth Electronics Inc.Field Application Engineer

Michael Eckert


What is an Inductor ?

technical view:a piece of wire wounded on something

a filter

an energy-storage-part (short-time)

examples:


What is an EMC-Ferrite ?

Technical view:Frequency dependent filter

Absorber for RF-energy

examples:

EMC Snap-Ferrites EMC-Ferrites forFlatwire

SMD-Ferrites


Magnetic Field Strenght H of some configurations

RIH⋅⋅

=π2

RINH⋅⋅⋅

=π2

lINH ⋅

=

long, straight wire

Toroidal Coil

Long solenoid

(e.g. rod core indcutor)


• Dosing pump for chemicalsindustry.

Example: Conducted Emission Measurement


• Power supply V 1.0

PCB

Buck Converter ST L4960/2.5A/fs 85-115KHz

Conducted Emission Measurement


• Power supply V 1.1

PCB

Schematic

Conducted Emission Measurement


Awareness:

• Select the right parts for yourapplication

• Do not always look on cost

Very easy solution with adramatic result!!!

Choke before Choke after

or


What is permeability [ur]?

– Permability (µr): describe the capacity of concentration of the magnetic flux in the material.

typical permeabilities [µr] :

- Iron powder / Superflux : 50 ~ 150

- Nickel Zinc : 40 ~ 1500

- Manganese Zinc : 300 ~ 20000

HB r ⋅⋅= μμ0

Magnetic induction in ferrite:

Non-Linear Function ( µr!)

The relative permeability is dependent on frequency……


||0 μω LR =

|0 μω LjX L =

resistive component(material it self)frequency dependent core losses

„ideell“ (without material) inductive componentfrequency dependent inductive portion

Tanδ = RXL

Loss factor

Frequency dependent Permeability

complex permeability


Measurement of Core Material Properties

Core Material(Fe / MnZn/ NiZn/ …)

Impedance Analyser

RL

XL

Core Material Parameter

XRZ L22 +=


Permeability vs. Temperature

23

700

400- 40%

85

+ 40%Curie-Temperatur

Loses its magentic properties


How to find the best part for my application ?

Core Material Comparison


When to use which type of material for filtering ?

=> It depends on frequency-range to filter !

Res

istiv

epa

rtof

Impe

danc

e


When to use which material for store energy

=> It depends on application frequency for EACH Core-Material !

Indu

ctiv

epa

rtof

Impe

danc

e


When to use an Inductor ?When to use an EMC-Ferrite ?

=> Application Storage Choke:

Request: lowest possible losses at application frequency

high Q-factor

=> Application as absorber-filter:Request: highest losses possible at application frequency range

low Q/factor


Vergleich Güte Ferrit <=> Induktivität

Inductor vs. EMI-Ferrit:

Frequency [MHz]

Q-F

acto

r

Ferrite

Inductor

Comparison Q-Factor: Ferrite vs. Inductor Q = XLR

Losses


Frequency-Spectrum and suggested Core Materials

Iron-PowderMnZn

NiZn

Suggested CoreMaterials for filtering: Ceramic

Let´s take a closer look...


150KHz 30MHz 1GHz

Frequency range for EMI tests


Noise SpectrumRadiated Configuration

Conducted Configuration

EUT

150MHz 450MHz

FCC limit lineNoise madeby the device

Overview FCC Tests


What‘s the main Interference we see on the board level?

Common Mode Interference(asym. Interference)

Differential Mode Interference(sym. Interference)


How can we find out what interference we have on thePCB‘s?

Take a Snap Ferrite and fix it on the cable(both lines e.g. VCC and GND)

noise reductionor „noise immuntiy increase“

you have Common Mode Interference

if not

you have Differential Mode Interference


Example: Flyback Converter

Appearance of differential noises on the input line of a Flyback Converter

differential interference occurs mainly at lower frequencies

L1

N

PE

Switch (e.g Transistor)

mostly high Cap‘s >100uF; Xc=1/(ωxC)

differential interference



Example: Flyback Converter

L1

N

PE

parasitic capacities ; in the lower pF (e.g: VCC layer to GND layer( coupling))

Switch (e.g Transistor)

mostly high Cap‘s >100uF; Xc=1/(ωxC)

common mode interference

common mode interference

common mode interference occurs mainly at higherfrequencies

Appearance of common mode noises on the input line of a Flyback Converter



Current Compensated Chokes


Replace a „Snap Ferrit“ by a common choke ?

We can replace ferrite by common mode choke

Both are common mode filters !

First check for the technologie and look the impedance curve


Impedance increase vs. numbers of turnsin

crea

seIm

peda

nce

Fres.-decrease


N1

N2

Functionality of a common mode choke:

The operational current (diff. mode) is routed by all relevant conductors through the core(e.g. +/- or L/N). That´s why the magnetic fields of these two conductors compensate eachother to zero => no influence on the wanted signalThe disturbance current flows on both wires in the same direction and generates a magneticfield in the toroidal core => the choke is able to filter unwanted noises.

operational current / wanted signal(diff. mode)

disturbance current(common mode)

Sour

cee.g

. 24A

C Su

pply

Load

5V A

C/DC

Con

verte

r


sectional winding bifilar winding

< advantage? >

Common Mode Choke


Why bifilar / sectional winding ?

sectional winding:• Same number of windings placed opposed on the toroidal core• In addition to the common mode suppression (asym. noises) the high leakage inductance also

allows filtering of differential interferences (sym. noises)

bifilar winding:• Parallel wiring around the core (in most cases we use wires with different colors)• Small leakage inductance and therefore less attenuation of high-frequency

differential noises


For example: WE-SL2 744227SCommon Mode suppression

Differential Mode suppressionis high!

Sectional winding:

ATTENTION:SECTIONELL WINDING MUST BEUSED ON MAIN-POWER SUPPLY !


Bifilar winding vs. Sectional winding

For example: WE-SL2 744227Common Mode suppression

Differential Mode suppressionis low!

Differential Mode S-Type

interference(Common Mode )

signal (Differential)


Advantage of a Common Mode Choke

Filtering with two inductors or ferrites

Signal before filtering after filtering

Rise-time of the signal is affected,which could cause problems forfast data and signal lines

which occurs from the DC current the filteringperformance is shortened.

because of the pre-magnetization (saturation)


Filtering with a Common Mode Choke

Signal before filtering after filtering

no affect on the signal rise-time, because of magnetic field compensation

no influence of the wanted signal(the two windings are magneticallycoupled)

no pre-magnetization (saturation) occurs from the DC current, because of magnetic coupling

much better performance vs. two separate inductors or ferrites

Advantage of a Common Mode Choke


Filtering the USB 2.0 interface via CMC


USB 2.0 Filtering via WE-CNSW

measurement point TP2

EMI-filter EMI-filter

90 Ohm @ 100 MHz C.M. 600 Ohm @ 100 MHz C.M. WE-CBF 20 Ohm @ 240 MHz D.M. 40 Ohm @ 240 MHz D.M. 120 Ohm @ 100 MHz


Portfolio of eiSos:

common mode chokes by Würth Elektronik

for 115VAC / 250VAC / max. 20A for signal / data linesUmax. = 42VAC (80VDC) / I up to 5A

THT with sectionalwinding

WE-LF WE-CMB

THT SMD sectional bifilar

common mode Ferrite-Bridges6-hole-

Ferrite bead

WE-SL seriesWE-VB / VB 2

WE-CNSWcommon mode

Chip-bead

WE-SLseries

WE-SL seriesWE-CNSW

WE-VB / VB 2


Common mode chokes in SMD:

WE-CNSWNiZn Z = 67–2200 Ohm @ 100 MHz

NiZn (für L < 100uH)

WE-SL

WE-CMS

for signal / data lines up to Imax = 0,4 A


for signal / data lines up to Imax = 5 A

WE-VB2

NiZn L~ 15 uH… ~ 80 uH


NiZn Z = 52 Ohm @ 100 MHz

MnZn (für L > 60uH)

L ~ 10 µH ... ~ 47 mH

f (MHz)

10001001010,1


f (MHz)

10001001010,1

WE-SL3

NiZn L ~ 20 uH… ~ 100 uH

NiZn L ~ 10 µH… ~ 330 µH

WE-SL1

WE-SL2

MnZn (für L < 250uH)




WE-SL5

NiZn L ~ 120 uH… ~ 4,7 mH


NiZn (für L > 51uH)

L ~ 25 µH ... ~ 47 mH

Common mode chokes in SMD:


Common mode chokes for THT:

f (MHz)

10001001010,1

WE-LF

MnZn L ~ 1 mH… ~ 47 mH

NiZn L ~ 10 µH… ~ 100 µH

WE-VB

Ferrite bridge(WE-MLS)

for 115 / 230VAC up to Imax = 6 A

for VCC-lines, signal / data lines up to Imax = 1,6A

für VCC-lines, signal / data lines up to Imax = 16 A

WE-CMB for 115 / 230VAC up to Imax = 15 A

MnZn L ~ 150 uH… ~ 39 mH

NiZn Z = 264 – 334 Ohm


Ferritebridge WE-MLS:

With an adequat PCB layout it´s pos-sible to realize up to 5 applicationswith only 1 standard component !

Replacement for 6-Hole Ferrite-Bead Dual common mode choke; 4A

Examples:


Applications with the WE-MLS:

Dual CM choke

Z ~ 170 .. 350 Ω@ 100 MHz

I = 4 ARDC < 2 mΩ

Single CM choke

Z ~ 170 .. 350 Ω@ 100 MHz

I = 8 ARDC < 1 mΩ

Single CM choke

Z ~ 600 .. 900 Ω@ 100 MHz

I = 4 ARDC < 4 mΩ

4 windings

Z ~ 900 .. 1500 Ω@ 100 MHz

I = 4 ARDC < 10 mΩ

Z ~ 170 .. 350 Ω@ 100 MHz

RDC < 1 mΩ

Single winding

I = 16 A

optimal for e.g. filtering in power supplies (U < 60VDC), charger or sensortechnology


WE-SL

WE-SL 1

WE-SL 2

WE-SL 3

WE-SL 5

WE-CNSW

Size [mm] Impedance [Ω] Current [A]

2.0 x 1.2 x 1.23.2 x 1.6 x 1.9

12.7 x 10.5 x 5,75

9.2 x 6.0 x 5.0

6.5 x 3.6 x 1.65

9.2 x 6.6 x 2.5

10.0 x 8.2 x 6.5

Application

0.28 – 0.40.20 – 0.37

0.20 – 2.70

0.30

0.40 – 1.60

0.50 – 0.70

0.35 – 2.50

130 – 91060 – 400

1100 – 14400

300 – 2000

1250 – 5000

290 – 13000

1000 – 20000

USB 2.0Firewire/ high speed dataline

VCC Power & Datalines

VCC Power & Datalineshigher current ratings

ISDNTelecom Applications

VCC Power Lines

744212xxxNEW

NEW744252/253xxx

NEW744272xxx

PCMCIA cards

Common mode chokes for SMD:


Differential Mode suppression : SMD-Ferrit WE-CBF


Impedance: SMD-Ferrite (Chip Bead)

XL(NiZn)

Advantage of SMD-Ferrites:broadband, frequency-dependent

Absorber for RF-noise in the frequencyrange 10 MHz ... > 1GHz

with very low DC-Resistance(< 0,8 Ohm max. !)

resistive component

inductive component


Which impedance do we need ?

0

10

20

30

40

50

60

Level [dBµV/m]

30M 40M 50M 70M 100M 200M 300M 400M 600M 1G

Frequency [Hz]


Insertion Loss Model

Equivalent circuit of Filter

Equivalent circuitof source

Equivalent circuit of system impedance

)(log20 dBinZZ

ZZZABA

BFA

+++

=Insertion Loss =>


Simulation Model Cap

Simulation Model Fer.

The real world........ !

Equivalent Circuit of Filter-ComponentsEquivalent circuit of source

Equivalentcircuit of load

for Inductor and Capacitor onecan find Simulation-Models

? ?

source

Noisesource

load


Starting Point: Practical figures for ZA / ZB

* Groundplanes : Impedance range 1 ... 2 Ω

* VCC-Distribution: Impedance range 1 ... 2 Ω

* Video-/ Clock-/ Dataline: Impedance range 50 ... 90 Ω

* Long Datalines: Impedance range 90 ... >150 ΩWith this we can make a first decision of a Ferrite-Impedance ZFwhich would suppress noise in our application :


Which Impedance ZF is needed ?

Example 1: required attentuation= 20dB @ 200 MHz VCC-Distribution

180Ω

=> goto Nomogramm:

180 Ω => chosen: 220 Ω

Impedance of the Ferrite

Atte

nuat

ion

[dB

]


Insertion Loss vs. Impedance of Source/ Load (ZA / ZB)

A = -32 dB max.with ZA = ZB = 10 Ω = constant

A = -18 dB max.with ZA = ZB = 50 Ω = constant

A = - 8 dB max.with ZA = ZB = 200 Ω = constant

A = - 3 dB max.with ZA = ZB = 1000 Ω = constant

with ZA = ZB = 5000 Ω =constantno effect in filtering !

SMD-Ferrite ZF = 600 Ohm @ 100 MHz

Frequency (Hz)

Inse

rtio

n Lo

ss(d

B)


Simulation with RF Sim 99 or SWITCHER CAD III

Demostrationa) via equivalent circuit

b) via S-Parameters

)(log20 dBinZZ

ZZZABA

BFA

+++

=Insertion Loss =>

S-parameters are available on our homepage


SMD-Ferrite listed in LTSpice/SwitcherCADIII

Freeware !Download www.linear.com_


SMD-Ferrites LTSpice/SwitcherCADIII

You can sort database by :Part.Nr.; RDC; Current ; Impedance @100MHz ormaximum Impedance @ which Frequency

SwCAD III.lnk


Saturation of the ferrite(Impect of DC-bias (magnetize))

To high inrush current(switch on current )

Wrong layout of the filter circuit(noise coupling)

Wrong compination of components(Lsrf = Csrf >> no wideband suppression)

Examples:

Design-In mistakes of Ferrites


Impect of DC-bias (pre-magnetization (saturation)

800Ω@100MHZ (0ADC)

420Ω@100MHZ (1,7ADC)

230Ω@100MHZ (3ADC)

742792515 (3A typ)



Impect of DC-bias (pre-magnetization (saturation)


Ferrite can be destroyed , muss not fail directly.„creeping process“

Io = Uo/ (RDC ferrite +R ESR capacity)

= 12V / (0,15Ω+0,5Ω) = 18A18 time higher current

Destroy the ferrite due over current/inrush current

DCDC RL

Iconst= 500mA

7427907Uo=12V

100uF

RDC 0,15Ω




Destroy the ferrite due switch on current(no current limitation was done by the customer)


Basic Design-Rules of EMC-Filters

Low DC-Resistance; high Absorption forRF-noise; no SRF-Point

Low ESR; „zero“-Ohm-Path to GND for RF-noisestabilzie VCC for Pulse-Currents


Inductance of connection:SMD-types 1 nH ... 5 nHwired 10 nH ... 50 nH !

ESR:SMD-types 20 mΩ ... 300 mΩ

up to 1 Ω(see Datasheet )

Equivalent Circuit: Capacitor


IZI [Ω]

f [MHz]

ωLS

ωCS

1

RS

log

log


Equivalent circuit : Inductor /Ferrite

Parasitic Capacitance:SMD-EMC-Ferrite 5 fF ... 5 pFwinded Inductors 10 pF ... 500 pF !

Losses:Inductors (at SRF ! ) up to 30 kΩSMD-EMC-Ferrite (broadband !) 10 Ω ... 3 kΩ


IZI [Ω]

f [MHz]

ωLpωCp

1

RP

log

log


1 mm ~ 1nH

1 via ~ 0.5 nH0.5 nH @ 100 MHz = 0.314 Ω

0.5 nH @ 1 GHz = 3.14 Ω !

Zges: ESR+Lr (2nH)+Lvia(0,5nH)

100nF= 0,2Ω+1,2Ω+0,3Ω= 1,7Ω@100MHz


Size: 0603/X7R


LC-Lowpassfilter Layout Lowpassfilter

Why will this Filter not work properly at RF-Frequencies ?

Ground-Level

Grounding / Layout


Grounding / Layout

Inductive coupling

Capacitive coupling

Bypass fornoise

too long tracks

Contraction for RF

more vias to GND= low impedance

Connection to Case

bad solution optimized


Layout for Ground

IC2a

IGND

The GND-Potential is affectedby current driven throughground-pin of semiconductor !

IGND

IC2a

Separated ways for RF-currentof C2a and semiconductor

More vias = smaller DCR/L

bad good

vias to ground


Impedance vs. Frequency of Capacitors

3/4 parts are needed to,,,,,,,,,,,, !!


Paralleled Capacitors

a:100nF // 100 pF(without Ferrite !)Attention !

Resonant Circuit !!

b:1 x 100nF

c:2 x 100nF paralleledlower Impedance

SRF ~ 20 MHz


Simulation of parallel resonance due to the wrong choiceof Cap‘s (100nF; 1nF; 100pF)

Simulation with RF Sim 99 or SWITCHER CAD III

Correct choice of parallel Cap‘s (100nF; 22nF; 5nF)Attenuation of at least 12dB in the range of 1 MHz to 500MHz

Optimal solution: (100nF; SMD Ferrit)Wideband attenuation of the complete frequency range


Simulation-Modell for EMC-Ferrites and

Model as Parallel-Circuit withconstant Parametern forRp / Lp / Cp

can be used in anySimulationprogram(like P-SPICE or Electronics Workbench, ...) !

Datas: see Book„Trilogy of Inductors“Seite 113ff

Power Inductors


Recommended Filtercircuits

Suggested Circuits

ATTENTION !Self-Resonant-Frequencyof Components !!!

smaller C = higher SRF

If you choose SMD-Ferrite instead of Inductor L = no Resonance with C = broadband filtering

Source Impedance Load Impedance

low

low low

high

high

high

high orunknown

low orunknown

high orunknown

low orunknown


Noise source

Source: USB/Battery

DC-DC-Converter LT13043,3V to 5V

PD Typ M 22uH7447779122

LC-Filter

Pi-Filter

Crystal Oscillators(25MHz and 100MHz)to generate the noisespectrum

f

A


Filter Topologies

50 Ohm Ref. Line

3xC Capacitance Filter

„L“Filter with SMD Ferrite

„L-C“ Filter with SMDFerrite und Capacitor

„PI“ Filter

„T“ Filter


The „L“ Ferrite –Filter


The „L“ Ferrite –Filter

Insertion Loss

-40

-35

-30

-25

-20

-15

-10

-5

0

1 10 100 1000

Frequenz in MHz

in d

B

Ferrite-Filter Simulation modell)


Ferrite –Filter: Measurement vs. Simulation

Insertion Loss

-40

-35

-30

-25

-20

-15

-10

-5

0

1 10 100 1000

Frequenz in MHz

in d

B

Ferrite-Filter (Insertion Loss)Ferrite-Filter Simulation modell)


LC-Filter

L=742 792 093

C=100nF


LC-Filter

Dämpfung

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

1 10 100 1000

Frequenz in MHz

in d

BLC-Filter (Simulationsmodell)


LC-Filter: Measurement vs. Simulation

Dämpfung

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

1 10 100 1000

Frequenz in MHz

in d

B

LC-Filter (Einfügedämpfung)LC-Filter (Simulationsmodell)


Parallel capacitors

C1= 1nF

C2=10nF

C3=100nF


Parallel capacitors

Dämpfung

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

1 10 100 1000

Frequenz in MHz

in d

BC-Filter (Simulationsmodell)


C-Filter: Measurement vs. Simulation

Dämpfung

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

1 10 100 1000

Frequenz in MHz

in d

B

C-Filter (Einfügedämpfung)C-Filter (Simulationsmodell)


Pi-Filter

C1=1nF

L=742 792 093

C2=100nF


Pi-Filter

Dämpfung

-120

-100

-80

-60

-40

-20

0

1 10 100 1000

Frequenz in MHz

in d

BPi-Filter (Simulationsmodell)


Pi-Filter: Measurement vs. Simulation

Dämpfung

-120

-100

-80

-60

-40

-20

0

1 10 100 1000

Frequenz in MHz

in d

BPi-Filter (Einfügedämpfung)Pi-Filter (Simulationsmodell)



Dämpfung

-120

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

Pi-Filter (Einfügedämpfung)Pi-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)PI-Filter (Spectrum Analyzer)


T-Filter

L1=742 792 040

C=100nF

L2=742 792 092


T-Filter

Dämpfung

-120

-100

-80

-60

-40

-20

0

1 10 100 1000

Frequenz in MHz

in d

BT-Filter (Simulationsmodell)


T-Filter: Measurement vs. Simulation

Dämpfung

-120

-100

-80

-60

-40

-20

0

1 10 100 1000

Frequenz in MHz

in d

B

T-Filter (Einfügedämpfung)T-Filter (Simulationsmodell)



Insertion Loss

-120

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

Ferrite-Filter (Insertion Loss)Ferrits-Filter Simulation modell)Ref.-Meas. (Spectrum Analyzer)



Insertion Loss

-120

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

Ferrite-Filter (Insertion Loss)Ferrite-Filter Simulation modell)Ref.-Meas. (Spectrum Analyzer)Ferrite-Filter (Spectrum Analyzer)



Dämpfung

-120

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

T-Filter (Einfügedämpfung)T-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)T-Filter (Spectrum Analyzer)



Dämpfung

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

C-Filter (Einfügedämpfung)C-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)



Dämpfung

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

BC-Filter (Einfügedämpfung)C-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)C-Filter (Spectrum Analyzer)


LC-Filter: Measurement vs. Simulation

Dämpfung

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

LC-Filter (Einfügedämpfung)LC-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)


LC-Filter: Mesaurement vs. Simulation

Dämpfung

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

LC-Filter (Einfügedämpfung)LC-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)LC-Filter (Spectrum Analyzer)



Dämpfung

-120

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

B

Pi-Filter (Einfügedämpfung)Pi-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)



Dämpfung

-120

-100

-80

-60

-40

-20

0

20

1 10 100 1000

Frequenz in MHz

in d

BT-Filter (Einfügedämpfung)T-Filter (Simulationsmodell)Ref.-Messung (Spectrum Analyzer)


Testboard VCC-decoupling

5,1VDC Trimmer 10K

RL=220Ω

R=470Ω

IC

74LS132

CL=47pF

Filter circuit 1uF; Ferrit; 1uF


VCC- decoupling via discrete π-Filter

IC VCC

π-Filter: 1uF-742792093-1uF

GND GND

Attenuation

-140

-120

-100

-80

-60

-40

-20

0

1 10 100 1000Frequency [MHz]

dB

Pi-Filter Simulation


Filter Circuit Simulation: VCC- π -Filter

Impedance Characteristic Zmax@100MHz742792093

SwCAD III.lnk


Noise-Spectrum on VCC

no filtering on Vcc(condition: max. Hold)


Simulation VCC decoupling 1uF

IC VCC

C-Filter with 1uF

GND

Attenuation

-140

-120

-100

-80

-60

-40

-20

0


dB

C-Filter

4MHz

50dB

Step 1:1uF Cap.


Attenuation

-140

-120

-100

-80

-60

-40

-20

0


dB

without filteringC-Filter 1uF C-Filter Simulation

IC VCC

C-Filter: 1uF

GND

Step 1:1uF Cap.

4MHz

50dB

Simulation VCC decoupling 1uF


Attenuation

-140

-120

-100

-80

-60

-40

-20

0


dB

LC-Filter-SimulationC-Filter Simulation

Step 2:1uF Cap.& Ferrite IC VCC

LC-Filter: 1uF-742792093

GND

Simulation VCC decoupling 1uF - Ferrite

main attenuationdone by the ferrite


Step 2:1uF Cap.& Ferrite IC VCC

LC-Filter: 1uF-742792093

GND

Attenuation

-140

-120

-100

-80

-60

-40

-20

0


dB

C-Filter 1uF

LC-Filter 1uF_742792093

without filtering

LC-Filter-Simulation


main attenuationdone by the ferrite


IC VCC


GND GND

Attenuation

-140

-120

-100

-80

-60

-40

-20

0


dB

LC-Filter-Simulation

C-Filter Simulation

Pi-Filter-Simulation


Step 3:1uF//1uF Cap.& Ferrite

additional attenuationfor the lower frequency


IC VCC


GND GND

Simulation VCC decoupling 1uF – Ferrite – 1uF

Attenuation

-140

-120

-100

-80

-60

-40

-20

0


dB

C-Filter-SimulationC-Filter 1uF LC-Filter 1uF_742792093 PI-Filter 1uF//1uF_742792093without filteringLC-Filter-SimulationPi-Filter-Simulation

Step 3:1uF//1uF Cap.& Ferrite

additional attenuationfor the lower frequency


no filtering on Vcc

Final Result

filtering on VccIC VCC


GND GND


You want to know more ??

Look at our Book:

Chap.1: Basicskeep it simple, stupid

Chap.2: ComponentsDescriptions, Applications, Simulation Models and many more

Chap.3: Filter-CircuitsDesign, Grounding, Layout, Tipps

Chap.4: ApplicationsCircuit, suggested parts, Layout

Chap.5: Appendicesfrom A to Z


Online:

www.wewww.we--online.comonline.com

wurth electronics inc. field application engineer michael

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