Common Mode Chokes by Würth Elektronik

Welcome! Inductors & EMC-Ferrites Basics - Parts and Applications

Wurth Electronics Inc. Field Application Engineer Michael Eckert

Würth Elektronik eiSos © May/2006 Michael Eckert What is an Inductor ?

technical view: a piece of wire wounded on something a filter an energy-storage-part (short-time) examples:

Würth Elektronik eiSos © May/2006 Michael Eckert What is an EMC-Ferrite ?

Technical view: Frequency dependent filter Absorber for RF-energy examples:

EMC Snap-Ferrites EMC-Ferrites for SMD-Ferrites Flatwire

Würth Elektronik eiSos © May/2006 Michael Eckert Magnetic Field Strenght H of some configurations

I long, straight wire H = 2⋅π ⋅R

N⋅I Toroidal Coil H = 2⋅π ⋅R

N⋅I Long solenoid H = l (e.g. rod core indcutor)

Würth Elektronik eiSos © May/2006 Michael Eckert Example: Conducted Emission Measurement

• Dosing pump for chemicals industry.

Würth Elektronik eiSos © May/2006 Michael Eckert Conducted Emission Measurement

• Power supply V 1.0

PCB

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

Würth Elektronik eiSos © May/2006 Michael Eckert Conducted Emission Measurement

• Power supply V 1.1

PCB

Schematic

Würth Elektronik eiSos © May/2006 Michael Eckert Awareness:

• Select the right parts for your application

• Do not always look on cost

Very easy solution with a dramatic result!!!

Choke before Choke after

Würth Elektronik eiSos © May/2006 Michael Eckert What is permeability [ur]?

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

typical permeabilities [µr] : Magnetic induction in ferrite: - Iron powder / Superflux : 50 ~ 150 - Nickel Zinc : 40 ~ 1500 B = μ0 ⋅μr ⋅ H - Manganese Zinc : 300 ~ 20000

Non-Linear Function ( µr!)

The relative permeability is dependent on frequency……

Würth Elektronik eiSos © May/2006 Michael Eckert Frequency dependent Permeability

R Tanδ = XL Loss factor ω || R = L 0 μ resistive component (material it self) frequency dependent core losses ω | X L = j L 0 μ „ideell“ (without material) inductive component frequency dependent inductive portion

complex permeability Würth Elektronik eiSos © May/2006 Michael Eckert Measurement of Core Material Properties

R L

X L

Core Material Impedance Analyser Core Material Parameter (Fe / MnZn/ NiZn/ …) = 2 + 2 Z R X L

Würth Elektronik eiSos © May/2006 Michael Eckert Permeability vs. Temperature

+ 40% 700 Curie-Temperatur - 40% Loses its magentic properties 400

23 85

Würth Elektronik eiSos © May/2006 Michael Eckert How to find the best part for my application ?

Core Material Comparison

Würth Elektronik eiSos © May/2006 Michael Eckert When to use which type of material for filtering ? Resistive part of Impedance

=> It depends on frequency-range to filter !

Würth Elektronik eiSos © May/2006 Michael Eckert When to use which material for store energy Inductive part of Impedance

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

Würth Elektronik eiSos © May/2006 Michael Eckert 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

Würth Elektronik eiSos © May/2006 Michael Eckert Inductor vs. EMI-Ferrit:

Vergleich Güte Ferrit <=> Induktivität XL Comparison Q-Factor: Ferrite vs. Inductor Q = R Losses

Inductor Q-Factor

Ferrite

Frequency [MHz]

Würth Elektronik eiSos © May/2006 Michael Eckert Frequency-Spectrum and suggested Core Materials

Suggested Core Materials for filtering: Ceramic NiZn MnZn Iron-Powder

Let´s take a closer look...

Würth Elektronik eiSos © May/2006 Michael Eckert Frequency range for EMI tests

150KHz 30MHz 1GHz

Würth Elektronik eiSos © May/2006 Michael Eckert Overview FCC Tests

Radiated Configuration Noise Spectrum

EUT

FCC limit line Conducted Configuration Noise made by the device 150MHz 450MHz

Würth Elektronik eiSos © May/2006 Michael Eckert What‘s the main Interference we see on the board level?

Common Mode Interference (asym. Interference)

Differential Mode Interference (sym. Interference)

Würth Elektronik eiSos © May/2006 Michael Eckert How can we find out what interference we have on the PCB‘s?

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

noise reduction or „noise immuntiy increase“

you have Common Mode Interference

if not

you have Differential Mode Interference

Würth Elektronik eiSos © May/2006 Michael Eckert Example: Flyback Converter

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

mostly high Cap‘s >100uF; Xc=1/(ωxC)

differential interference L1

differential interference Switch (e.g Transistor) P E

differential interference occurs mainly at lower frequencies

Würth Elektronik eiSos © May/2006 Michael Eckert Example: Flyback Converter

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

mostly high Cap‘s >100uF; Xc=1/(ωxC)

common mode interference

differential interference N

common mode interference Switch (e.g Transistor)

P E

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

common mode interference occurs mainly at higher frequencies

Würth Elektronik eiSos © May/2006 Michael Eckert Current Compensated Chokes

Würth Elektronik eiSos © May/2006 Michael Eckert 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

Würth Elektronik eiSos © May/2006 Michael Eckert Impedance increase vs. numbers of turns increase Impedance

Fres.-decrease Würth Elektronik eiSos © May/2006 Michael Eckert Functionality of a common mode choke:

operational current / wanted signal N1 (diff. mode)

disturbance current (common mode) Load Source e.g. 24AC Supply 5V AC/DC Converter

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 each other to zero => no influence on the wanted signal The disturbance current flows on both wires in the same direction and generates a magnetic field in the toroidal core => the choke is able to filter unwanted noises.

Würth Elektronik eiSos © May/2006 Michael Eckert Common Mode Choke sectional winding bifilar winding

< advantage? >

Würth Elektronik eiSos © May/2006 Michael Eckert 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

Würth Elektronik eiSos © May/2006 Michael Eckert Sectional winding:

For example: WE-SL2 744227S Common Mode suppression

Differential Mode suppression is high!

ATTENTION: SECTIONELL WINDING MUST BE USED ON MAIN-POWER SUPPLY ! Würth Elektronik eiSos © May/2006 Michael Eckert Bifilar winding vs. Sectional winding

For example: WE-SL2 744227 Common Mode suppression

signal (Differential)

Differential Mode S-Type Differential Mode suppression is low!

interference(Common Mode )

Würth Elektronik eiSos © May/2006 Michael Eckert Advantage of a Common Mode Choke

Filtering with two inductors or ferrites

Signal before filtering after filtering

¾Rise-time of the signal is affected, which could cause problems for fast data and signal lines

which occurs from the DC current the filtering performance is shortened. ¾because of the pre-magnetization (saturation)

Würth Elektronik eiSos © May/2006 Michael Eckert Advantage of a Common Mode Choke

Filtering with a Common Mode Choke

Signal before filtering after filtering

¾ no affect on the signal rise-time, because of magnetic field compensation ¾ no influence of the wanted signal (the two windings are magnetically coupled)

¾ no pre-magnetization (saturation) occurs from the DC current, because of magnetic coupling ¾ much better performance vs. two separate inductors or ferrites

Würth Elektronik eiSos © May/2006 Michael Eckert Filtering the USB 2.0 interface via CMC

Würth Elektronik eiSos © May/2006 Michael Eckert 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

Würth Elektronik eiSos © May/2006 Michael Eckert Portfolio of eiSos:

common mode chokes by Würth Elektronik

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

THT with sectional THT SMD sectional bifilar winding

common mode WE-SL series WE-LF WE-CMB Ferrite- WE-SL WE-SL series WE-VB / VB 2 Bridges series WE-CNSW WE-CNSW 6-hole- WE-VB / VB 2 common mode Ferrite bead Chip-bead

Würth Elektronik eiSos © May/2006 Michael Eckert Common mode chokes in SMD:

WE-CMS for signal / data lines up to Imax = 5 A NiZn Z = 52 Ohm @ 100 MHz

WE-SL for signal / data lines up to Imax = 5,6 A MnZn (für L > 60uH) NiZn (für L < 100uH)

L ~ 10 µH ... ~ 47 mH

WE-CNSW for signal / data lines up to Imax = 0,4 A NiZn Z = 67–2200 Ohm @ 100 MHz

WE-VB2 for signal / data lines up to Imax = 0,5 A NiZn L~ 15 uH… ~ 80 uH f (MHz) 0,1 1 10 100 1000

Würth Elektronik eiSos © May/2006 Michael Eckert Common mode chokes in SMD:

WE-SL2 for signal / data lines up to Imax = 1,6 A MnZn (für L < 250uH) NiZn (für L > 51uH) L ~ 25 µH ... ~ 47 mH

WE-SL1 for signal / data lines up to Imax = 0,3 A NiZn L ~ 10 µH… ~ 330 µH

WE-SL3 for signal / data lines up to Imax = 0,7 A NiZn L ~ 20 uH… ~ 100 uH

WE-SL5 for signal / data lines up to Imax = 2,5 A NiZn L ~ 120 uH… ~ 4,7 mH f (MHz) 0,1 1 10 100 1000

Würth Elektronik eiSos © May/2006 Michael Eckert Common mode chokes for THT:

Ferrite bridge für VCC-lines, signal / data lines up to Imax = 16 A (WE-MLS) NiZn Z = 264 – 334 Ohm

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

NiZn L ~ 10 µH… ~ 100 µH

WE-LF for 115 / 230VAC up to Imax = 6 A MnZn L ~ 1 mH… ~ 47 mH

WE-CMB for 115 / 230VAC up to Imax = 15 A MnZn L ~ 150 uH… ~ 39 mH

f (MHz) 0,1 1 10 100 1000

Würth Elektronik eiSos © May/2006 Michael Eckert Ferritebridge WE-MLS:

With an adequat PCB layout it´s possible to realize up to 5 applications with only 1 standard component !

Examples:

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

Würth Elektronik eiSos © May/2006 Michael Eckert Applications with the WE-MLS:

Dual CM choke Single CM choke Single CM choke 4 windings Single winding Z ~ 170 .. 350 Ω Z ~ 170 .. 350 Ω Z ~ 600 .. 900 Ω Z ~ 900 .. 1500 Ω Z ~ 170 .. 350 Ω @ 100 MHz @ 100 MHz @ 100 MHz @ 100 MHz @ 100 MHz I = 4 A I = 8 A I = 4 A I = 4 A I = 16 A RDC < 2 mΩ RDC < 1 mΩ RDC < 4 mΩ RDC < 10 mΩ RDC < 1 mΩ optimal for e.g. filtering in power supplies (U < 60VDC), charger or sensor technology

Würth Elektronik eiSos © May/2006 Michael Eckert Common mode chokes for SMD:

Size [mm] Impedance [Ω] Current [A] Application

2.0 x 1.2 x 1.2 130 – 910 0.28 – 0.4 USB 2.0 WE-CNSW 3.2 x 1.6 x 1.9 60 – 400 0.20 – 0.37 Firewire/ high speed dataline

ISDN WE-SL 1100 – 14400 0.20 – 2.70 12.7 x 10.5 x 5,75 Telecom Applications

WE-SL 1 PCMCIA cards NEW 6.5 x 3.6 x 1.65 300 – 2000 0.30 744212xxx

WE-SL 2 9.2 x 6.0 x 5.0 1000 – 20000 0.40 – 1.60 VCC Power & Datalines

WE-SL 3 VCC Power & Datalines NEW 9.2 x 6.6 x 2.5 1250 – 5000 0.50 – 0.70 744252/253xxx higher current ratings

WE-SL 5 NEW 10.0 x 8.2 x 6.5 290 – 13000 0.35 – 2.50 VCC Power Lines 744272xxx

Würth Elektronik eiSos © May/2006 Michael Eckert Differential Mode suppression : SMD-Ferrit WE-CBF

Würth Elektronik eiSos © May/2006 Michael Eckert Impedance: SMD-Ferrite (Chip Bead)

XL(NiZn)

inductive component

Advantage of SMD-Ferrites: resistive component broadband, frequency-dependent Absorber for RF-noise in the frequency range 10 MHz ... > 1GHz with very low DC-Resistance (< 0,8 Ohm max. !)

Würth Elektronik eiSos © May/2006 Michael Eckert Which impedance do we need ?

Level [dBµV/m]

0 30M 40M 50M 70M 100M 200M 300M 400M 600M 1G

Frequency [Hz]

Würth Elektronik eiSos © May/2006 Michael Eckert Insertion Loss Model

Equivalent circuit of Filter Equivalent circuit Equivalent circuit of of source system impedance

Z A + ZF + ZB Insertion Loss => A = 20log in (dB) Z A + ZB

Würth Elektronik eiSos © May/2006 Michael Eckert The real world...... !

Simulation load source Model Fer.

Noise source Simulation ? Model Cap ?

Equivalent Circuit of Equivalent circuit of source Filter-Components Equivalent circuit of load for Inductor and Capacitor one can find Simulation-Models

Würth Elektronik eiSos © May/2006 Michael Eckert 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 Ω

With this we can make a first decision of a Ferrite-Impedance ZF which would suppress noise in our application :

Würth Elektronik eiSos © May/2006 Michael Eckert Which Impedance ZF is needed ?

Example 1: required attentuation = 20dB @ 200 MHz VCC-Distribution => goto Nomogramm: 180 Ω => chosen: 220 Ω Attenuation [dB] Attenuation

Impedance of the Ferrite 180Ω

Würth Elektronik eiSos © May/2006 Michael Eckert Insertion Loss vs. Impedance of Source/ Load (ZA / ZB)

with ZA = ZB = 5000 Ω =constant no effect in filtering !

A = - 3 dB max.

with ZA = ZB = 1000 Ω = constant A = - 8 dB max.

with ZA = ZB = 200 Ω = constant

A = -18 dB max.

with ZA = ZB = 50 Ω = constant Insertion Loss (dB) A = -32 dB max.

with ZA = ZB = 10 Ω = constant

Frequency (Hz)

SMD-Ferrite ZF = 600 Ohm @ 100 MHz

Würth Elektronik eiSos © May/2006 Michael Eckert Simulation with RF Sim 99 or SWITCHER CAD III Demostration

a) via equivalent circuit

b) via S-Parameters

Z + Z + Z Insertion Loss => A = 20 log A F B in (dB ) Z A + Z B S-parameters are available on our homepage

Würth Elektronik eiSos © May/2006 Michael Eckert SMD-Ferrite listed in LTSpice/SwitcherCADIII

Freeware !Download www.linear.com_

Würth Elektronik eiSos © May/2006 Michael Eckert SMD-Ferrites LTSpice/SwitcherCADIII

You can sort database by : Part.Nr.; RDC; Current ; Impedance @100MHz or maximum Impedance @ which Frequency SwCAD III.lnk Würth Elektronik eiSos © May/2006 Michael Eckert Design-In mistakes of Ferrites

Examples: ¾ Saturation of the ferrite (Impect of DC-bias (magnetize))

¾ To high inrush current (switch on current )

¾ Wrong layout of the filter circuit (noise coupling)

¾ Wrong compination of components (Lsrf = Csrf >> no wideband suppression)

Würth Elektronik eiSos © May/2006 Michael Eckert 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)

Würth Elektronik eiSos © May/2006 Michael Eckert Impect of DC-bias (pre-magnetization (saturation)

Würth Elektronik eiSos © May/2006 Michael Eckert Design-In mistakes of Ferrites

Destroy the ferrite due over current/inrush current

Iconst= 500mA RDC 0,15Ω

DC 7427907 R DC Uo=12V L 100uF

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

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

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

Würth Elektronik eiSos © May/2006 Michael Eckert Design-In mistakes of Ferrites

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

Würth Elektronik eiSos © May/2006 Michael Eckert Basic Design-Rules of EMC-Filters

Low DC-Resistance; high Absorption for RF-noise; no SRF-Point

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

Würth Elektronik eiSos © May/2006 Michael Eckert Basic Design-Rules of EMC-Filters

Equivalent Circuit: Capacitor IZI [Ω] log

ωLS 1

ωCS

f [MHz]log Inductance of connection: ESR: SMD-types 1 nH ... 5 nH SMD-types 20 mΩ ... 300 mΩ wired 10 nH ... 50 nH ! up to 1 Ω (see Datasheet )

Würth Elektronik eiSos © May/2006 Michael Eckert Basic Design-Rules of EMC-Filters

Equivalent circuit : Inductor /Ferrite Losses: Inductors (at SRF ! ) up to 30 kΩ SMD-EMC-Ferrite (broadband !) 10 Ω ... 3 kΩ RP IZI [Ω] log 1 ωC ωLp p

Parasitic Capacitance: SMD-EMC-Ferrite 5 fF ... 5 pF f [MHz]log winded Inductors 10 pF ... 500 pF !

Würth Elektronik eiSos © May/2006 Michael Eckert Basic Design-Rules of EMC-Filters

1 mm ~ 1nH 1 via ~ 0.5 nH 0.5 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

Würth Elektronik eiSos © May/2006 Michael Eckert Grounding / Layout

LC-Lowpassfilter Layout Lowpassfilter

Ground-Level

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

Würth Elektronik eiSos © May/2006 Michael Eckert Grounding / Layout bad solution optimized

Inductive coupling

Contraction for RF Capacitive coupling

Bypass for noise Connection to Case

more vias to GND too long tracks = low impedance

Würth Elektronik eiSos © May/2006 Michael Eckert Layout for Ground

bad good

IGND

I GND vias to IC2a ground IC2a The GND-Potential is affected Separated ways for RF-current by current driven through of C2a and semiconductor ground-pin of semiconductor !

More vias = smaller DCR/L

Würth Elektronik eiSos © May/2006 Michael Eckert Impedance vs. Frequency of Capacitors

3/4 parts are needed to,,,,,,,,,,,, !! Würth Elektronik eiSos © May/2006 Michael Eckert Paralleled Capacitors

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

SRF ~ 20 MHz b: 1 x 100nF

c: 2 x 100nF paralleled lower Impedance

Würth Elektronik eiSos © May/2006 Michael Eckert Simulation with RF Sim 99 or SWITCHER CAD III

¾ Simulation of parallel resonance due to the wrong choice of Cap‘s (100nF; 1nF; 100pF)

¾ Correct choice of parallel Cap‘s (100nF; 22nF; 5nF) Attenuation of at least 12dB in the range of 1 MHz to 500MHz

¾ Optimal solution: (100nF; SMD Ferrit) Wideband attenuation of the complete frequency range

Würth Elektronik eiSos © May/2006 Michael Eckert Simulation-Modell for EMC-Ferrites and Power Inductors

Model as Parallel-Circuit with constant Parametern for Rp / Lp / Cp

can be used in any Simulationprogram (like P-SPICE or Electronics Workbench, ...) ! Datas: see Book „Trilogy of Inductors“ Seite 113ff

Würth Elektronik eiSos © May/2006 Michael Eckert Recommended Filtercircuits

Source Impedance Load Impedance

low high Suggested Circuits

ATTENTION ! high high Self-Resonant-Frequency of Components !!!

high or high or smaller C = higher SRF unknown unknown

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

Würth Elektronik eiSos © May/2006 Michael Eckert Noise source

Source: USB/Battery

Pi-Filter

PD Typ M 22uH 7447779122 Crystal Oscillators LC-Filter (25MHz and 100MHz) DC-DC-Converter LT1304 to generate the noise 3,3V to 5V spectrum

Würth Elektronik eiSos © May/2006 Michael Eckert Filter Topologies

50 Ohm Ref. Line

3xC Capacitance Filter

„L“Filter with SMD Ferrite „L-C“ Filter with SMD Ferrite und Capacitor

„PI“ Filter

„T“ Filter

Würth Elektronik eiSos © May/2006 Michael Eckert The „L“ Ferrite –Filter

Insertion Loss

-5

-10

-15

-20 in dB

-25

-30

-35 Ferrite-Filter Simulation modell) -40 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert Ferrite –Filter: Measurement vs. Simulation

Insertion Loss

-5

-10

-15

in dB in -20

-25

-30 Ferrite-Filter (Insertion Loss) -35 Ferrite-Filter Simulation modell)

-40 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert LC-Filter

L=742 792 093 C=100nF

Würth Elektronik eiSos © May/2006 Michael Eckert LC-Filter

0 Dämpfung -10

-20 LC-Filter (Simulationsmodell)

-30

-40

-50

-60 in dB in

-70

-80

-90

-100 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert LC-Filter: Measurement vs. Simulation

0 Dämpfung -10

LC-Filter (Einfügedämpfung) -20 LC-Filter (Simulationsmodell)

-30

-40

-50

in dB in -60

-70

-80

-90

-100 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert Parallel capacitors

C1= 1nF

C2=10nF

C3=100nF

Würth Elektronik eiSos © May/2006 Michael Eckert Parallel capacitors

0 Dämpfung -10 C-Filter (Simulationsmodell) -20

-30

-40

-50 in dB in

-60

-70

-80

-90 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert C-Filter: Measurement vs. Simulation

Dämpfung -10

C-Filter (Einfügedämpfung) -20 C-Filter (Simulationsmodell)

-30

-40

-50 in dB in

-60

-70

-80

-90 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert Pi-Filter

C1=1nF L=742 792 093

C2=100nF

Würth Elektronik eiSos © May/2006 Michael Eckert Pi-Filter

Dämpfung

0 Pi-Filter (Simulationsmodell) -20

-40

-60 in dB in

-80

-100

-120 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert Pi-Filter: Measurement vs. Simulation

Dämpfung

Pi-Filter (Einfügedämpfung) -20 Pi-Filter (Simulationsmodell)

-40

-60 in dB in

-80

-100

-120 1 10 100 1000 Frequenz in MHz

Würth Elektronik eiSos © May/2006 Michael Eckert Pi-Filter: Measurement vs. Simulation

Dämpfung

-20

-40

in dB in -60

-80

-100 Pi-Filter (Einfügedämpfung) Pi-Filter (Simulationsmodell) Ref.-Messung (Spectrum Analyzer) PI-Filter (Spectrum Analyzer) -120 1 10 100 1000 Frequenz in MHz

L1=742 792 040 C=100nF

L2=742 792 092

0 Dämpfung

-20 T-Filter (Simulationsmodell)

-40

-60 in dB in

-80

-100

-120 1 10 100 1000 Frequenz in MHz

0 Dämpfung

-20 T-Filter (Einfügedämpfung) T-Filter (Simulationsmodell)

-40

-60 in dB in

-80

-100

-120 1 10 100 1000 Frequenz in MHz

Insertion Loss

-20

-40 in dB -60

-80

Ferrite-Filter (Insertion Loss) -100 Ferrits-Filter Simulation modell) Ref.-Meas. (Spectrum Analyzer) -120 1 10 100 1000 Frequenz in MHz

Insertion Loss

-20

-40 in dB in -60

-80 Ferrite-Filter (Insertion Loss) -100 Ferrite-Filter Simulation modell) Ref.-Meas. (Spectrum Analyzer) Ferrite-Filter (Spectrum Analyzer) -120 1 10 100 1000 Frequenz in MHz

20 Dämpfung

0 T-Filter (Einfügedämpfung) T-Filter (Simulationsmodell) Ref.-Messung (Spectrum Analyzer) -20 T-Filter (Spectrum Analyzer)

-40

-60 in dB in

-80

-100

-120 1 10 100 1000 Frequenz in MHz

Dämpfung

0 C-Filter (Einfügedämpfung) C-Filter (Simulationsmodell) Ref.-Messung (Spectrum Analyzer) -20

-40 in dB in

-60

-80

-100 1 10 100 1000 Frequenz in MHz

Dämpfung

20 C-Filter (Einfügedämpfung) C-Filter (Simulationsmodell) Ref.-Messung (Spectrum Analyzer) 0 C-Filter (Spectrum Analyzer)

-20

-40 in dB

-60

-80

-100 1 10 100 1000 Frequenz in MHz

20 Dämpfung

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

-20

-40 in dB in

-60

-80

-100 1 10 100 1000 Frequenz in MHz

20 Dämpfung

0 LC-Filter (Einfügedämpfung) LC-Filter (Simulationsmodell) Ref.-Messung (Spectrum Analyzer) LC-Filter (Spectrum Analyzer) -20

-40 in dB in

-60

-80

-100 1 10 100 1000 Frequenz in MHz

Dämpfung

-20

-40

in dB in -60

-80

-100 Pi-Filter (Einfügedämpfung) Pi-Filter (Simulationsmodell) Ref.-Messung (Spectrum Analyzer) -120 1 10 100 1000 Frequenz in MHz

20 Dämpfung

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

-20

-40

-60 in dB in

-80

-100

-120 1 10 100 1000 Frequenz in MHz

Filter circuit 1uF; Ferrit; 1uF

IC 74LS132

RL=220Ω

R=470Ω CL=47pF 5,1V DC Trimmer 10K

π-Filter: 1uF-742792093-1uF

IC VCC

GND GND

0 Attenuation -20

-40 -60

-80 Pi-Filter Simulation dB -100

-120 -140 1 10 100 1000 Frequency [MHz]

Impedance Characteristic Zmax@100MHz 742792093

no filtering on Vcc (condition: max. Hold)

Step 1: C-Filter with 1uF 1uF Cap.

IC VCC

GND

Attenuation

0 -20

-40 50dB -60 C-Filter -80 dB -100

-120 -140 1 10 100 1000 4MHz Frequency [MHz]

Step 1: C-Filter: 1uF 1uF Cap. IC VCC

GND

Attenuation

0 -20 -40 without filtering 50dB -60 C-Filter 1uF dB -80 C-Filter Simulation -100 -120 -140 14MHz 10 100 1000 Frequency [MHz]

Step 2: LC-Filter: 1uF-742792093 1uF Cap.

IC V & Ferrite CC

GND

Attenuation 0

-20

-40

-60 LC-Filter-Simulation dB -80 C-Filter Simulation

-100

-120 main attenuation done by the ferrite -140 1 10 100 1000 Frequency [MHz]

Step 2: LC-Filter: 1uF-742792093 1uF Cap.

& Ferrite IC VCC

GND

Attenuation

-20

-40 C-Filter 1uF

-60 LC-Filter 1uF_742792093 dB -80 without filtering

-100 LC-Filter-Simulation

-120 main attenuation done by the ferrite -140 1 10 100 1000 Frequency [MHz]

Step 3: π-Filter: 1uF-742792093-1uF 1uF//1uF Cap.

& Ferrite IC VCC

GND GND

Attenuation

0 -20 -40 LC-Filter-Simulation -60 C-Filter Simulation dB -80 Pi-Filter-Simulation -100 -120 additional attenuation -140 for the lower frequency 1 10 100 1000 Frequency [MHz]

Step 3: π-Filter: 1uF-742792093-1uF 1uF//1uF Cap.

& Ferrite IC VCC

GND GND

Attenuation 0

-20

-40 C-Filter-Simulation -60 C-Filter 1uF LC-Filter 1uF_742792093 dB -80 PI-Filter 1uF//1uF_742792093 without filtering -100 LC-Filter-Simulation Pi-Filter-Simulation -120 additional attenuation for the lower frequency -140 1 10 100 1000 Frequency [MHz]

π-Filter: 1uF-742792093-1uF

IC VCC

GND GND no filtering on Vcc filtering on Vcc

Look at our Book: Chap.1: Basics keep it simple, stupid Chap.2: Components Descriptions, Applications, Simulation Models and many more Chap.3: Filter-Circuits Design, Grounding, Layout, Tipps Chap.4: Applications Circuit, suggested parts, Layout Chap.5: Appendices from A to Z