SEAT 2010 Tutorial

Current vs. Voltage Characteristics Chip Varistors ....................................................................................25Resistance vs. Temperature Characteristics NTC Thermistors ..............................................................................26

Chapter 3 Simulation .............................................................. 27Pulse Response Simulation Single-end .........................................................................................28 Differential .........................................................................................30TDR Simulation Differential .........................................................................................32Temperature Rise Inductor Temperature Rise Due to DC Current ................................34 Temperature Rise of Multilayer Ceramic Capacitor Due to AC Ripple Current ...........................................................36Electro-static Discharge Simulation .................................................38 NTC Thermistor Simulation ................................................................40

Chapter 4 Tools ....................................................................... 43User-Defi ned Filter Parallel Connection of Multilayer Ceramic Capacitors .....................44 Creation of an LC Filter .....................................................................46Characteristic Impedance Calculator Single Line.........................................................................................48 Coupled Line .....................................................................................49

Chapter 5 Other Functions .................................................... 51Graph Operation Axes Setting & Marker ......................................................................52 Alarm Zone & Graph Line ..................................................................53Update to the Latest Version .............................................................54Technical Support Tools ......................................................................55

Appendix1 S-parameter Basics ...................................................57

Appendix2 Classifi cation of Electronic Components...........69

CONTENTS

Chapter 1 Outline & Product Search ...................................... 1Outline of SEAT .......................................................................... 2 SEAT Basics ............................................................................... 3Product Search Product Name Search & Simple Search .............................................4 Advanced Search ................................................................................5 Series Range Chart .............................................................................6

Chapter 2 Displaying Characteristics ..................................... 7 Frequency Characteristics Impedance Characteristics of Chip Beads .........................................8 Impedance Characteristics of Common Mode Filters ........................9 Impedance and ESR Characteristics of Multilayer Ceramic Capacitors ...................................................................................10 ESL Characteristics of Multilayer Ceramic Capacitors .....................11 tanδ (Dielectric Loss Tangent) Characteristics of Multilayer Ceramic Capacitors .....................................................................12 Inductance and Q Characteristics of Inductors ................................13 S-parameter Characteristics (Return Loss, Insertion Loss) of Three-Terminal Filters ..................................................................14 S-parameter Characteristics (Crosstalk) of Three-Terminal Filter Arrays ..................................................................................15 S-parameter Characteristics (Series-thru & Shunt-thru) of Multilayer Ceramic Capacitors ....................................................16 Mixed Mode S-parameter Characteristics (Return Loss, Insertion Loss) of Common Mode Filters ....................................17 Mixed Mode S-parameter Characteristics (Crosstalk) of Common Mode Filter Arrays .......................................................18 Description of Frequency Characteristics Buttons ..........................19DC Bias Characteristics Inductors ...........................................................................................21 Multilayer Ceramic Capacitors ..........................................................22Temperature Characteristics Inductors ...........................................................................................23 Multilayer Ceramic Capacitors ..........................................................24

Chapter 1

Outline & Product Search

2

Outline of SEAT

SEAT stands for SElection Assistant of TDK components. SEAT displays the characteristics of components and allows simple product simulations. Main Functions

· Displays component characteristics(1) Frequency characteristics (e.g. impedance, S-parameter)(2) DC bias/temperature characteristics (3) I-V characteristics of chip varistor(4) R-T characteristics of NTC thermistor

· Simulation functions(1) Pulse response (single/differential)(2) TDR (single/differential)(3) Temperature rise(4) Electro-static discharge(5) Output voltage of NTC thermistor

· Tools(1) User-defi ned fi lter(2) User-defi ned component(3) Characteristic impedance calculator

· Other functions(1) Varied product search functions(2) Updates by Internet

Product List

Product

Specifi cations

DC bias/temperature characteristics

Search functions

Frequency characteristics Simulation functions

3

From the Product List, select a product for DUT (Device User Test) in a simulation.

Start the simulation condition form to set conditions.

Click the Simulate button.

SEAT Basics

For both displaying characteristics and simulation, operation starts by selecting a target product from the Product List on the left side of the window.The Product List is classifi ed according to category, sub-category, size and series. To select a product for evaluation, click the mouse.

Select a product from the Product List.

Click one or more Characteristics button on the ribbon.

Select from the Product List.

Product specifi cations are updated.

Refer to Chapter 3

Procedures to display characteristics

Simulation procedures

Refer to Chapter 2

4

Product Search [Product Name Search & Simple Search]

Product Name Search

Simple Search

SEAT has several functions to search products. This section explains “Product Name Search” and “Basic Search.”

Enter a character string included in the product name (part of the name is accepted) in the [Product Name] text box in the [Home] tab, and click or .

(1) Open the [Simple Search] drop-down menu in the [Home] tab and select the Product List and Category.

(2) For Size and other items, set search conditions (any order is accepted).

(3) Search result is displayed in the list on the right. → To select a product, double-click the name in the Product List.

A wild card (e.g. * or ?) cannot be used at Product Name Search.

5

Product Search [Advanced Search]

The Advanced Search is a more detailed search than Simple Search. For example, in a character string search, a wild card (e.g. or ?) can be used; in a search by product specifi cations, a range of values can be specifi ed; or a search can be made by frequency characteristics. In addition, SEAT has a function to display the distribution status as a product map.

Double-clicking a map symbol allows a product to be selected in the Product List.

List display

Map display

Search by specifi cations

Search by frequency characteristic

Map option

A wild card can be used

6

Product Search [Series Range Chart]

The Series Range Chart is a function to create a chart for the range of main characteristics of each product series.

Range chart

Chart list

Double-clicking allows a product to be selected in the Product List.

(1) Select a category and series.

(2) Click the Chart Update button.

Chapter 2

Displaying Characteristics

8

Impedance Characteristics of Chip Beads

Chip beads are parts used to prevent EMI and control decoupling of LSI power source lines and to control over/under shooting of digital signals.

Step1

Step2

Select MMZ1005B121C from the Product List.

Select the [Impedance] tab, and then click the |Z|, R, or X button.

· The R / X cross point depends on the type of chip bead. The cross point affects the noise removal effectiveness and waveform strain.

· By changing the DC bias in the [Impedance] tab, it is possible to see the frequency characteristics for the applied DC bias.

|Z|: Magnitude of Impedance

X:Reactance of Impedance

R: Resistance of Impedance

Result

9

Impedance Characteristics of Common Mode Filters

Step1

Step2

Common mode fi lters are used for power source circuits and differential transmission lines. Select a mode F(Common/Differential) to display the impedance characteristics.

Select ACM2520-301-2P from the Product List.

Select [Mode] from the [Impedance] tab, and then click the |Z| button.

· Common mode fi lter characteristics generally need to be |Zc|>>|Zd|.· Other characteristics such as R and Ls are also displayed according to the

mode. For example, Lsc indicates the equivalent series inductance for common mode.

|Zc|: Magnitude of Common Mode Impedance

|Zd|: Magnitude of Differential Mode Impedance

Result

10

Impedance and ESR Characteristics of Multilayer Ceramic Capacitors

Step1

Step2

Multilayer ceramic capacitors are used for various purposes such as matching RF circuits and decoupling LSI power source lines. ESR (Equivalent Series Resistance) value of capacitors, which are used for decoupling, are evaluated in order to understand the infl uence of voltage variation. In recent years, some have been designed to have an arbitrary ESR value to reduce the infl uence of voltage variation.

Select CERD2CX5R0G106M (ESR Control Type) from the Product List.

Select the [Impedance] tab, and then click the |Z| or R button.

· Generally, the ESR of multilayer ceramic capacitors depends on the size and capacity, but is usually from several mΩ to tens of mΩ. However, ESR control type products are from tens of mΩ to several Ω.

Result

|Z|: Magnitude of Impedance

R: Resistance of Impedance (ESR)

11

ESL Characteristics of Multilayer Ceramic Capacitors

Step1

Step2

In order to reduce the infl uence of voltage variation due to LSI switching, the ESL (Equivalent Series Inductance) value of capacitors used for decoupling needs to be as small as possible.

Select C0816JB1C104K (LW Flipped Type) from the Product List.

Select the [Impedance] tab, and then click the Ls button.

· The ESL for standard multilayer ceramic capacitors depends on the size and capacity, but it is usually from 0.5 to 1nH. Low ESL type capacitors such as fl ip type are from several tens of pH to 0.2nH.

(Reference) Standard Type

LW Flipped Type

Result

12

tan (Dielectric Loss Tangent) Characteristics of Multilayer Ceramic Capacitors

Step1

Step2

The tan δ is evaluated as the value indicating the purity of the capacitor reactance. The smaller the value, the smaller the power loss of the capacitor (Ideal capacitors have no power loss.).

Select C3216X7R1H474K from the Product List.

Select the [Impedance] tab, and then click the D (tan δ) button.

The tan δ is normally displayed as a “%”.

Result Self-Resonant Frequency

Capacitor tan δ

13

Inductance and Q Characteristics of Inductors

Step1

Step2

Inductors used for RF circuit matching need to have a high Q in order to transmit the RF signal with minimal loss. Inductance differs according to the frequency, so it is important to know the inductance at the used frequency instead of the nominal inductance value.

Select MLG0603Q1N0CT (Multilayer Ceramic / High-Q Type) from the Product List.

Select the [Impedance] tab, and then click the Ls or Q button.

1.002nH at 100MHz0.938nH at 2.4GHz

High-Q Type

(Reference) Standard Type

Result-Ls

Result-Q

14

S-parameter Characteristics (Return Loss, Insertion Loss) of Three-Terminal Filters

Three-terminal fi lters allows for multiple inductors and capacitors to be integrated into one chip, which makes it possible for the signal to be quickly attenuated, and the attenuation amount can be increased. The impedance characteristics of three-terminal fi lters cannot express the overall characteristics, so the single-end S-parameter is normally used to express attenuation amount in dB.

Step1

Sij

Select MEM2012S25R0T001 from the Product List.

Step2

While confi rming the Port Assignment, select the Output / Input Port from the [S-parameter] tab, and then click the |S| button.

The relationship between the part terminal and Port No. is described in the Port Assignment at the bottom left of the SEAT screen.

(Example) S11 The amount of the incident signal from

Port 1 is refl ected to Port 1 (Return Loss)S21 The amount of the incident signal from

Port 1 is transmitted to Port 2 (Insertion Loss)

· Single-end S-parameter

Output Port Input Port

|S11| (Return Loss)

|S21| (Insertion Loss)

Result

15

S-parameter Characteristics (Crosstalk) of Three-Terminal Filter Arrays

Step1

Step2

A three-terminal fi lter array contains multiple integrated fi lters, which consist of multiple inductors and capacitors in one chip. They can greatly reduce the mounting area, so they are often used for high-density mounting equipment such as mobile phones. However, fi lters are located close to each other, so when the frequency is high, the infl uence of crosstalk can become a problem.

Select MEA1210D501R from the Product List.

While confi rming the Port Assignment, select the Output / Input Port from the [S-parameter] tab, and click the |S| button.

|S21| (Near-End Crosstalk)

|S31| (Far-End Crosstalk)

Result

16

S-parameter Characteristics (Series-thru & Shunt-thru) of Multilayer Ceramic Capacitors

Step1

Step2

Either Series-thru or Shunt-thru can be selected as the S-parameter for some multilayer ceramic capacitors and chip varistors that are listed in SEAT. Be sure not to make a mistake when displaying the characteristics.

Select C1005JB1H221K from the Product List.

While confi rming the Port Assignment, select either Series / Shunt and the Output / Input Port from the [S-parameter] tab, and then click the |S| button.

Result

|S21|(Series-thru)

1 2

|S21| (Shunt-thru)

1 2

17

Mixed Mode S-parameter Characteristics (Return Loss, Insertion Loss) of Common Mode Filters

Common mode fi lters were formerly evaluated using common mode / differential mode impedance. In recent years, differential transmission has become faster and is now evaluated using the mixed mode S-parameter. It is expressed using a single-end S-parameter and mode additional characters (such as c and d).

Step1

Smnij

Select TCM1210H-900-2P from the Product List.

Step2

While confi rming the Port Assignment, select the Mode and Output / Input Port from the [S-parameter] tab, and then click the |S| button.

The Mixed Mode S-parameter Port No. is shown in red as the Logical Port.

(Example)Scd21 Amount of the applied Differential Mode

signal from logical Port 1 converted to Common Mode and transmitted to

logical Port 2.

· Mixed Mode S-parameter

Output Mode

Input Mode

Output Port

Input Port

|Sdd21| (Differential Mode Insertion Loss)

|Sdd11| (Differential Mode Return Loss)

Result

|Scc21| (Common Mode Insertion Loss)

18

Mixed Mode S-parameter Characteristics (Crosstalk) of Common Mode Filter Arrays

Step1

Step2

A common mode fi lter array is used for portions where multiple channels of differential transmission lines are laid such for DVIs. However, when high-speed signals are handled, the infl uence of crosstalk cannot be ignored.

Select TCM1608G-900-4P from the Product List.

While confi rming the port schematic, select the Mode and the Output / Input Port from the [S-parameter] tab, and then click the |S| button.

|Sdd21| (Differential Mode Near-End Crosstalk)

|Sdd31|(Differential Mode Far-End Crosstalk)

Result

19

Description of Frequency Characteristics Buttons - 1

Impedance

S-parameter

Magnitude of Impedance

Resistance Impedance Phase Conductance Admittance PhaseEquivalent Parallel Inductance Equivalent Parallel

CapacitanceDissipation Factor (Loss)

Reactance

Magnitude of Admittance Susceptance

Equivalent Series Inductance

Equivalent Series Capacitance

Quality FactorSmith Chart

Magnitude of S-parameter Group Delay Smith Chart Power Loss

S-parameter Phase Standing Wave Ratio Power Scattering

20

Description of Frequency Characteristics Buttons - 2

Image Impedance

Rejection Ratio Balun

Image Impedance Imaginary Part

Image Impedance Real Part

Common Mode Rejection Ratio Amplitude BalanceCommon Mode Rejection Ratio

Differential Mode Rejection RatioPhase Balance

Differential Mode Rejection Ratio

Image Impedance Phase

Image Impedance

Rejection Ratio

Magnitude of Image Impedance

21

DC Bias Characteristics of Inductors

Step1

Step2

Generally, the value that is measured using a small amplitude signal of a particular frequency at room temperature is used as the representative value for inductor inductance. However, it is used under conditions where the DC is superimposed at the power source circuit. Therefore, the inductance can change greatly.

Select VLC5045T-6R8M from the Product List.

From the [DC Bias Characteristic] Group of the [DC-Bias/Temp. Chara.] tab, select and set the Frequency, Oscillation Level, and Ambient Temperature, and then click the Ls button.

20˚C

AmbientTemperature: -20˚C

Result

105˚C

22

DC Bias Characteristics of Multilayer Ceramic Capacitors

Step1

Step2

Generally, the value that is measured using a small amplitude signal of a particular frequency at room temperature is used as the representative value for multilayer ceramic capacitor capacitance. However, when DC bias is applied the same as the decoupling circuit, the capacitance can change greatly.

Select C3216X5R1H105K from the Product List.

From the [DC Bias Characteristic] Group of the [DC-Bias/Temp. Chara.] tab, select the Frequency, Oscillation Level, and Ambient Temperature, and then click the Cs button.

· The nominal capacitance for multilayer ceramic capacitors is measured based on conditions such as 1kHz-1Vrms and 120Hz-0.5Vrms.

· The following are the major rated voltage symbols for multilayer ceramic capacitors.

0G: 4V 0J: 6.3V 1A: 10V1C: 16V 1E: 25V 1H: 50V2A: 100V 2E: 250V 2J: 630V

Ambient Temperature: 20˚C

Result

23

Temperature Characteristics of Inductors

Step1

Step2

Generally, the value that is measured using a small amplitude signal of a particular frequency at room temperature is used as the representative value for inductor inductance. However, the inductance can change greatly depending on the ambient temperature.

Select VLC5045T-6R8M from the Product List.

From the [Temperature Characteristic] Group of the [DC-Bias/Temp. Chara.] tab, select and set the Frequency, Oscillation Level, and DC Bias, and then click the Ls button.

Result

DC Bias: 0A

0.8A

1.6A

24

Temperature Characteristics of Multilayer Ceramic Capacitors

Step1

Step2

Generally, the value that is measured using a small amplitude signal of a particular frequency at room temperature is used as the representative value for multilayer ceramic capacitor capacitance. However, the capacitance can change greatly depending on the ambient temperature.

Select C3216X5R1H105K from the Product List.

From the [Temperature Characteristic] Group of the [DC-Bias/Temp. Chara.] tab, select the Frequency, Oscillation Level, and Ambient Temperature, and then click the Cs button. · The following are the major temperature characteristic symbols for

multilayer ceramic capacitor JB: -25 to +85˚C/±10% JF: -25 to +85˚C/+30,-80%X5R: -55 to +85˚C/±15% X6S: -55 to +105˚C/±22%X7R: -55 to +125˚C/±15% X8R: -55 to +150˚C/±15%Y5V: -30 to +85˚C/+22,-82%

DC Bias: 0V

25V

Result

25

Current vs. Voltage Characteristics of Chip Varistors

Step1

Step2

Chip varistors are nonlinear devices that normally behave like multilayer ceramic capacitors. However, when a large voltage is applied, the resistance suddenly decreases and the current fl ows. In order to confi rm those characteristics, the current vs. voltage characteristics are displayed.

Select AVR-M1608C080MTAAB from the Product List.

From the [Other Chara.] tab, click the I-V button.

From around this point, the current suddenly fl ows.

Result

26

Resistance vs. Temperature Characteristics of NTC Thermistors

Step1

Step2

The resistance of NTC thermistors changes according to the temperature, and they are used as temperature sensors. The N in NTC stands for “Negative,” so they have a negative temperature coeffi cient (the higher the temperature, the smaller the resistance). The B constant is used as the representative characteristic for NTC thermistors. The B constant indicates the change rate according to the temperature. Therefore, the larger this value, the more sensitive to temperature the device is.

Select NTCG203EH471J from the Product List.

From the [Other Chara.] tab, click the R-T button.

(Reference) 4150K Gradient is large.

B Constant: 3250K

Result

Chapter 3

Simulation

28

Pulse Response Simulation [Single-end] (Setting)

Pulse waves used in digital transmission include the fundamental frequency and its harmonics. Harmonics signals are easily emitted from a short transmission line on a printed circuit board and cause unwanted radiation. For this reason, techniques using chip beads and the like are employed to attenuate only the harmonic components while maintaining the quality of digital signals.

Step1 Step3

Step2

Step4

Click the [Pulse Response Simulation-Single-end] button in the [Simulation/Tool] tab.

Select MMZ1005B121C from the Product List for DUT.

Set such conditions as input waveform, damping resistance, driver, receiver, transmission line, and measurement point (The example below gives the default setting.).

Click the [Simulate] button.

29

Pulse Response Simulation [Single-end] (Result)

MMZ1005B121C

With one chip bead, over/undershoots are reduced.

(Reference)MMZ1005D121C

Ringing occurs

Without fi lter

Result

Transmission waveform Spectrum

(Reference) MMZ1005D121C + Damping resistance (100 Ω)

Combination with damping resistance reduces ringing and greatly attenuates the harmonic components.

Damping resistance

30

Pulse Response Simulation [Differential] (Setting)

In recent years, differential transmission systems have been adopted for high-speed serial transmission such as USB and HDMI. Differential transmission is resistant to external noise and helps improve high-speed transmission; however, such factors as its asymmetric transmission lines and skew (time lag of differential signals) generate common-mode components. A common-mode current, even though only a small current, causes a great amount of unwanted radiation; to reduce these factors common-mode fi lters are employed.

Step1 Step3

Step2

Step4

Click the [Pulse Response Simulation-Differential] button in the [Simulation/Tool] tab.

Select ACM3225-102-2P from the Product List for DUT.

Set such conditions as input waveform, output/input impedance, transmission line, and measurement point (The example below gives the default setting.).

Click the [Simulate] button.

31

Pulse Response Simulation [Differential] (Result)

ACM3225-102-2P

Skew is reduced and transmission signals improved (only the common mode component is greatly reduced).

(Reference) MMZ1608R102A

Chip beads are not suitable for differential transmission.

Without fi lter

Result

Transmission waveform Transmission waveform (common mode component only)

32

TDR Simulation [Differential] (Setting)

TDR (Time Domain Refl ectometry) is a technique used to fi nd the characteristic impedance of a circuit based on the refl ected wave of the input step pulse. In particular, when signals of more than hundreds MHz are handled, transmission lines and components used are required to match as much as possible.

Step1 Step3

Step2

Step4

Click the [TDR Simulation-Differential] button in the [Simulation/Tool] tab.

Select ACM2012H-900-2P from the Product List for DUT.

Set such conditions as system impedance, input pulse (The example below gives the default setting.).

Click the [Simulate] button.

33

TDR Simulation [Differential] (Result)

ACM2012H-900-2P

For high-speed differential transmission, the product nearly matches 100 Ω .

Result

(Reference) Standard type

Example: HDMI specifi cations85 to 115 Ω

34

Inductor Temperature Rise Due to DC Current (Setting)

Step1 Step3

Step2

Step4

In an inductor used for a power supply circuit, sometimes high DC current fl ows occur, and power is consumed by the inductor coil resistance, resulting in a rise of inductor temperature. The temperature rises in proportion to the square of current values; in actual use particular attention needs to be paid to this point.

Click the [Other Simulations-Temperature Rise] button in the [Simulation/Tool] tab.

Set the Ambient Temperature in the [Inductor] tab (For Heat Resistance and DC Resistance reference values of the selected product are automatically entered.).

Select VLC6045-100M from the Product List.

Click the [Simulate] button.

· Heat Resistance refers to the temperature rise occurring when 1 W of electricity is consumed by the inductor. In other words, the smaller the value, the less the temperature is likely to rise with a large current fl ow.

35

Inductor Temperature Rise Due to DC Current (Result)

25˚C

Result

Ambient temperature : -20˚C

105˚C

36

Temperature Rise of Multilayer Ceramic Capacitor Due to AC Ripple Current (Setting)

Step1 Step3

Step2

Step4

The impedance of a multilayer ceramic capacitor decreases as the frequency increases; therefore, with a large high-frequency current fl ow, the temperature of the capacitor rises. Particularly, when the capacitor is used as a smoothing capacitor after rectifi cation, the temperature of the capacitor may sometimes rise due to the high ripple voltage; attention needs to be paid this point.

Click the [Other Simulations-Temperature Rise] button in the [Simulation/Tool] tab.

Set such conditions as power impedance in the [Capacitor] tab (For Heat Resistance the reference value of the selected product is automatically entered.).

Select C4532X5R1H155K from the Product List.

Click the [Simulate] button.

· Heat Resistance refers to the temperature rise occurring when 1 W of electricity is consumed by the capacitor. In other words, the smaller the value, the less the temperature is likely to rise with a large current fl ow.

37

Temperature Rise of Multilayer Ceramic Capacitor Due to AC Ripple Current (Result)

200kHz

Result

Frequency : 100kHz

500kHz

38

Electro-static Discharge Simulation (Setting)

If several kV of voltage is instantly discharged as static electricity, this may result in the breakdown of LSI. Chip varistors are often used as a countermeasure. They are a nonlinear device and under normal conditions behave like a capacitor, but when a certain level of voltage or higher is applied, resistance suddenly decreases and current fl ows (refer to Chapter 2: Current vs. Voltage Characteristics of Chip Varistors). Insertion of this component between LSI and the ground, prevents LSI breaks due to the large current when a high voltage is applied.

Step1 Step3

Step2

Step4

Click the [Other Simulations-Electro-static Discharge (Varistor)] button in the [Simulation/Tool] tab.

Set the CR model (The example below gives the default setting.).

Select AVR-M1005C080MTAAB from the Product List.

Click the [Simulate] button.

39

Electro-static Discharge Simulation (Result)

Result

Chip varistor→ Voltage is substantially reduced.

Without fi lter→ High voltage is applied on the load.

40

NTC Thermistor Simulation (Setting)

NTC thermistors are used as a temperature sensor, because their resistance varies according to the temperature (refer to Chapter 2: Resistance vs. Temperature Characteristics of NTC Thermistors). It is a general technique that the NTC thermistor is combined with several resistors, to which a voltage is applied, and from the changes of the output voltage a temperature is assessed.

Step1 Step3

Step2

Step4

Click the [Other Simulations-NTC Thermistor] button in the [Simulation/Tool] tab.

Set such conditions as circuit, input voltage, and resistance value (The example below gives the default setting.).

Select NTCG104BH103H from the Product List.

Click the [Simulate] button.

41

NTC Thermistor Simulation (Result)

ResultA steeper gradient indicates better sensitivity to temperature.

Max.

Typ.

Min.20kΩ

5kΩR1=1kΩ

Chapter 4

Tools

44

User-Defi ned Filter [Parallel Connection of Multilayer Ceramic Capacitors](Setting)

The user-defi ned fi lter is a function to create a virtual component by combining several components. For example, by connecting chip beads in series or connecting capacitors in parallel, their impedance characteristics can be confi rmed. In addition, by creating an LC fi lter using an inductor and capacitor, S-parameter characteristics (e.g. return loss, insertion loss) can also be checked.This section shows how to check impedance characteristics when three multilayer ceramic capacitors are connected in parallel.

0.01μF

0.1μF

1μF

Step1

Step2

Step3

Click the [Tool-User-defi ned Filter] button in the [Simulation/Tool] tab.

Open the [Parallel Connection (1Port)] tab, select capacitors to be combined from the Product List, and click the Apply button.(In this example, C1608JB1H103K (C=0.01μF), C1608JB1H104K (C=0.1μF), and C1608JB1E105K (C=1μF) are set.).

Enter an output name and comment, and click the [Create] button.

45

Magnitude of Impedance

User-Defi ned Filter [Parallel Connection of Multilayer Ceramic Capacitors] (Result)

C1608JB1H103K (C=0.01μF)

C1608JB1H104K (C=0.1μF)

Result

C1608JB1E105K (C=1μF)

Combined product: 3 Caps

The combined product is registered in the User Product List. In the Product Properties, the combination type, a list of combined products, and registration date are displayed.

User Product List

46

User-Defi ned Filter [Creation of an LC Filter] (Setting)

This section describes how to create an LC fi lter by connecting an inductor and multilayer ceramic capacitor (Shunt-thru).

0.1μF

1μH

1 2

Step1

Step2

Step3

Click the Tool-User-defi ned Filter button in the Simulation/Tool tab.

Open the [Cascade Connection (2Port)] tab, from the Product List select an inductor and capacitor to be combined, and click the Apply button.(In this example, MLP2012S1R0M (L=1μH) and C1608JB1H104K (C=0.1μF:Shunt-thru) are set).

Enter an output name and comment, and click the [Create] button.

Set S-parameter confi guration in the S-parameter tab on the ribbon.

47

User-Defi ned Filter [Creation of an LC Filter] (Result)

|S21| characteristics (insertion loss)

MLP2012S1R0M(L=1μH)

Result

The combined product is registered in the User Product List. In the Product Properties, the combination type, a list of combined products, and registration date are displayed.

User Product List

Combined product: LC FilterC1608JB1H104K (C=0.1μF/Shunt-thru)

48

Characteristic Impedance Calculator [Single Line]

Result

This tool calculates characteristic impedance based on the size of the printed circuit board (e.g. line width, thickness of the board material) and the relative permittivity of the material.

Step1

Step2

Step3

Click the [Tool-Characteristic Impedance Calculator] button in the [Simulation/Tool] tab.

Characteristic impedance (Z0) and effective relative permittivity (εeff) are calculated.

Select the line type from the list on the left.

With reference to the diagram, enter dimensions and relative permittivity, and click the [Calculate] button.

49

Characteristic Impedance Calculator [Coupled Line]

Following the same procedures as for the single line on the previous page, characteristic impedance for coupled lines can be calculated.

Result

Characteristic impedance (Z0) and effective relative permittivity (εeff) of the common/differential modes are calculated.

Chapter 5

Other Functions

52

Graph Operation [Axes Setting & Marker]

Graphs displayed in SEAT can be operated in standardized ways.

Axes Setting Marker

Set axes in the [XY Axis] group in the [Graph Setting] pane. Set a marker in the [Marker] group in the [Graph Setting] pane.

· To enlarge a specifi c area of the graph, hold the Ctrl key down and select the area with the mouse button.

· To set auto range settings for both X and Y axes, double-click on the graph.

Select items to be displayed by a marker(The background of the selected item turns white.).

Magnitude of Impedance

(chip beads)

Magnitude of Impedance

(chip beads)

53

Graph Operation [Alarm Zone & Graph Line]

Graphs displayed in SEAT can be operated in standardized ways.

Alarm Zone Graph Line

Set an alarm zone in the [Alarm Zone] group in the [Graph Setting] pane.

Set a graph line in the [Graph Line] group in the [Graph Setting] pane.

To change the graph line, select the relevant item(The background color of the selected item turns white).

Range of temperature characteristics X7R

Temperature characteristics of

a multilayer ceramic capacitor

|S21| characteristics of a three-terminal

fi lter with different reference impedances

Reference impedance of S-parameter: 50Ω

10Ω

150Ω

54

Update to the Latest Version

Step1 Step2

SEAT can be updated to the latest version by downloading only difference data; please ensure Internet connection. It takes only a few seconds to check if there is an update; please run update from time to time.

Ensure Internet connection and click the [Check for Updates] button in the [Window/Help] tab.

Follow the instructions of the wizard displayed in the window to update to the latest version.

55

TDK Technical Support Tools

In addition to SEAT, TDK provides a TDK Virtual Components Library (TVCL) and a Components Characteristic Viewer (CCV).

· SEAT (SElection Assistant of TDK components)→Software for Windows to display component characteristics and conduct simulations

· CCV (Components Characteristic Viewer)→Web application for displaying component characteristics on a browser

· TVCL (TDK Virtual Components Library) A data and modeling series used in circuit simulators

http://www.tdk.co.jp/eseat

http://www.tdk.co.jp/ccv

http://www.tdk.co.jp/etvcl

TVCL Content

Category Name Outline

General-purpose electronic component modeling series

S-parameter Data Library Data series of measured S-parameters

Equivalent Circuit Model Library Equivalent circuit modeling series in PDF format

SPICE Netlist Library Equivalent circuit modeling series in netlist format

Electronic component modeling series for simulators

Component Library for Cadence Allegro® PCB PI option Equivalent circuit models

Component Library for Cadence Allegro® PCB SI

Component Library for Zuken CR-5000 Lightning

Equivalent circuit models, circuit diagram symbols, footprint data

Component Library for Ansoft Designer® & NEXXIM®

Component Library for Agilent ADS

Component Library for AWR Microwave Offi ce

Appendix 1

S-parameter Basics

58

A1-1 Defi nition

The S-parameter (Scattering parameter) expresses device characteristics using the degree of scattering when an AC signal is considered as a wave. The word “scattering” is a general term that refers to refl ection back to the source and transmission to other directions. Figure A1-1 shows an optical analogy. The word "degree" indicates the amount of attenuation or amplifi cation, which is measured using the square root of the electric power. It is possible to understand all linear characteristics of the device based on the degree of scattering (S-parameter).

Figure A1-1 Conceptual diagram of S-parameter (optical analogy)

Transmission b2

Incidence a1

Refl ection b1

S11=b1/a1

S21=b2/a1

Ob

jec

t

The input and output ports of a device are numbered and the S-parameter that is “Incident at port j→Detected at port i” is described as Sij. Refl ection is represented as i = j, and transmission is described as i ≠ j. Therefore, in an n-port device, there are S-parameters of n2 pieces. When these S-parameters are aligned in a matrix form (A1-1), it is referred to as an S-matrix (Scattering matrix). For a more detailed defi nition, please refer to the textbooks [1] to [5].

(A1-1)

The S-parameter is a ratio, so it is basically a non-dimensional parameter (no unit). However, when describing the magnitude of the S-parameter, the unit "dB" is usually used with a common logarithm. For reference, the following Table A1-1 shows some representative values.

Table A1-1 Magnitude of the S-parameter

|Sij| 20log|Sij|

1 0dB

1/√2 -3dB

1/10 -20dB

1/100 -40dB

1/1000 -60dB

A1-2 Characteristics

The following characteristics are very helpful to understand S-parameter concepts. • If a device is lossless, the S-matrix becomes unitary. Therefore, a lossless 2-port device possesses

(Feldtkeller's formula).There is no loss, so the total amount of the scattering should be 100%. This shows the relationship, “When S21 (S11) is large, S11 (S21) is small.” • A passive 2-port device possesses

(The equal sign means lossless as mentioned

59

above.). Therefore, S-parameters for a passive device are not over 1 (0dB). The left side of the equation, , is referred to as the “Power Scattering Ratio”. This ratio shows how much electric power the device consumes. The smaller the result for the calculation( ), the greater the loss.• The cut-off frequency indicates the boundary between the passband and stopband of a device (fi lter). It can also be referred to as the frequency at which |Sij| = -3dB (half of the electric power passes). Therefore, if a 2-port device is lossless, |S11|=|S21| (this means the intersection point of the |S11| graph and the |S21| graph) at the cut-off frequency (refer to Figure A1-6 for an example).• If a device is reciprocal and is not a unidirectional component such as an isolator or circulator, the S-matrix is symmetric. Therefore, Sij = Sji. In mixed-mode S-parameters (refer to A1-10), Scc21=Scc12, Scd21=Sdc12, Sdc21=Scd12, Sdd21=Sdd12.

A1-3 Touchstone Format

Recently network analyzers are generally used to measure S-parameters. When the data that is to be transferred or that is used for simulation is described numerically, it is convenient to save it as a Touchstone format text fi le (.snp). Figure A1-2 shows an example of a Touchstone fi le.

For an explanation of the option line (# row), refer to Table A1-2 [6]. From the next row, there are numerical values that consist of multiple columns. The far left column indicates frequencies. In this example, they are DC to 6GHz (0Hz to 6000MHz). The frequency range and its interval are not ruled, but it must be arranged in increasing order. The remaining eight columns show the S-parameters at each frequency. The order for a 2-port device is S11, S21, S12, and S22. Each S-parameter is described using two real numbers. (In this example, MA format is used, so the magnitude and phase are real numbers.)Therefore, there are a total of eight columns; nine columns including the frequency. In other cases than a 2-port device, the Touchstone fi le looks similar, but there are some differences, for example, the numerical values may be ordered in a matrix form.The description format for other than 2-port devices is almost the same with some minor differences, e.g. the order of the numerical values may be in a matrix form.

Table A1-2 Rules of option line (# row)

Example Specifi cationMHz Unit of frequencyS Circuit matrix type (such as S/Z/Y)

MA Expressive form for complex numbersMA: Magnitude / Angle (Phase)RI: Real / ImaginaryDB: Magnitude in dB / AngleAngle (phase) unit is degree.

R50 reference impedance/ΩR50 refers to 50Ω

A1-4 Reasons Why S-Parameters are Used

As electronic devices have become faster and faster, greater emphasis has been placed on analog characteristics (SI=Signal Integrity) even in digital circuits, where in the past S-parameters were not so commonly

# MHz S MA R 500 0.00545 0 0.99455 0 0.99455 0 0.00545 00.30000 0.99950 -0.03754 0.00020 89.7291 0.00020 93.8341 0.99971 -0.023540.31523 0.99955 -0.03746 0.00020 89.8781 0.00020 89.0219 0.99992 -0.02312 · · · · · 6000.00 0.17892 -107.756 0.97259 -16.4840 0.97174 -16.5683 0.18224 -101.842

Figure A1-2 Example of Touchstone fi le

60

admittance is referred to as “Conductance G” and the imaginary part is referred to as “Susceptance B”.These are determined by two real numbers, so it is also possible to describe them in a composition circuit, e.g. capacitor and resistor (C-R) or inductor and resistor (L-R). A parallel or a series connection can be used for composition, so there are a total of four possible composition circuits (refer to Table A1-3). L and C in this circuit are mere parameters that express the imaginary part. For example, the reactance X divided by the angular frequency ω is the series inductance Ls. And the susceptance B divided by the angular frequency ω is the parallel capacitance Cp.Let's consider whether Cp indicates the capacitance of a capacitor in the following paragraph. The condition that Cp is the true capacitance of a capacitor (proportional to the permittivity of dielectric) is whether the objective capacitor can be expressed approximately using a C-R parallel circuit at that measured frequency. Negative Cp indicates that it is over the self-resonant frequency. When a resistive component is connected in series to a capacitor as in an electrolytic capacitor and the infl uence of the resistor (cathode) cannot be ignored (D >>1), it is not possible to understand what the Cp indicates even under the self-resonant frequency. So when we measure the capacitance of an electrolytic capacitor, Cs is usually used. Paradoxically, it is necessary

used. Now, S-parameters are being given more attention, and the following shows why and how S-parameters are used. • The transfer of electric signals or power (energy) can be expressed by S-parameters, which can show such physical quantities as attenuation of a fi lter or transducer gain of an active device.• When the size of a device at high-frequency is similar to the wavelength, it is necessary to consider the time difference for the location. It is easy to understand this phenomenon by using the concept of refl ection and transmission. Also, the calculation can be simpler. This is why the S-matrix for a transmission line can be described by the simple formula shown in (A1-13).• A passive device always has S-parameters (not divergence). Therefore, for example, it is valid to analyze an ideal transformer network.• It is diffi cult to achieve strict termination conditions such as open and short at high frequencies. Because of resistive termination, S-parameters can be measured at high frequencies. The measured amount makes calculation easier, as there is no need to convert to Z- or Y-parameters.

A1-5 Impedance

The characteristics of a linear 1-port (two-terminal) device can be described by one complex number, such as the impedance, admittance or refl ection coeffi cient. The following gives an overview of these coeffi cients.Impedance Z is the ratio of the voltage between terminals and the current through terminal. The inverse of this ratio is admittance Y. These are complex numbers that can be described using two real numbers such as real / imaginary numbers or a polar form. The real part of the impedance is referred to as “Resistance R” and the imaginary part is referred to as “Reactance X”. The real part of the

Table A1-3 Parameters to express impedance(Impedance Z=R+jX=|Z|ejθ, Admittance Y=G+jB=|Y|e-jθ, and L, C, Q, D = tanδ)

Domain

Inductive

Capacitive

Ls

Expression Circuit D= tanδ= 1/Q

X≧0,B≦00 /2 X= ω Ls B=－1/ω Lp

D= R/X =－G/B = 1/ (1+ Q2)XBRG

=－1/ (1+ D 2)Cs =Cp(1+ D 2)Lp = Ls (1+ D 2)

RG≒D 2, XB≒－1Cs≒Cp, Lp≒Ls

D= R/ω Ls=ω LpGD= cotδ =π /2－

D=－R/X =－G/BD= ωCsR= G/ωCpD=－cotθ

θ

θθ

δ = π /2+

Cs Cp

G

Lp

G

X=－1/ω Cs B= ω Cp

X 0,B 0－π/2 0

Interrelation

In case of D

R

R

61

to determine the measurement mode from either Cp or Cs before measuring. However, if two independent parameters (a complex number) are acquired, it is possible to convert them after measuring by using the formulae shown in Table A1-3.The real part of the impedance and admittance represents device loss. This is sometimes described using the ratio "D" (=tanδ, dissipation factor) between the real and imaginary parts. The δ is equal to the complimentary angle of the phase of either impedance or admittance. However, the value itself is rarely used. If the device is low loss, the tanδ is small, so it is described using a percentage. Also, "Q" (quality factor), the inverse of tanδ is widely used.When an inductor and a capacitor are connected in series or parallel, it becomes a resonance circuit. The following formula shows the relationship between Q of the resonance circuit (= central frequency divided by half bandwidth, describes the resonance sharpness) and the quality factor of the inductor (QL ) and capacitor (QC) when each has loss.

(A1-2) .L C

Therefore, the Q of inductor / capacitor can be defi ned as the Q of the resonance circuit when a lossless (Q = ∞) capacitor / inductor are connected, respectively.

A1-6 Smith Chart

The S-parameter of a 1-port device is referred to as the refl ection coeffi cient (in other words, S-parameters are the expansion of the refl ection coeffi cient to more than two ports). Refl ection coeffi cient Γ has the following relationship with impedance Z and admittance Y, which is also a 1-port parameter.

(A1-3) .

Where the reference impedance is Z0=1/Y0.The Smith chart has scaling of the complex plane of refl ection coeffi cient which enables impedance to be interpreted directly. As shown in (A1-3), if including the infi nite point, Γ, Z, and Y correspond one-to-one. Figure A1-3 shows this bilinear correspondence. This fi gure indicates that a passive device (right half of the impedance complex plane) locates inside of the Smith chart. Short (Z = 0Ω, the origin of the impedance plane) is the left edge (Γ=-1), open (Z= ∞Ω) is the right edge (Γ=1), and Z = Z0 is at the center (Γ= 0) in the Smith chart (Figure A1-4). The blue line in Figure A1-4 is "constant Q circle" for Q = 1. This is the curve that connects X = ±R points on the Smith chart, which is the half-line whose slope is ±1 in the impedance plane.

Figure A1-3 From impedance plane to Smith chart

X

R

Figure A1-4 Trace of series LCR circuit on a Smith chart

62

use, most circuits have a combination of these two circuits (refer to the next section for information about connections). In this sense, these two circuits are basic and the S-parameters given in SEAT are taken from these confi gurations.

Figure A1-5 Confi guration of 2-port circuits with a two-terminal component

(1)series-thru (2)shunt-thru

Theoretical formulae for the S-matrix of these confi gurations are given by

(A1-6)

(A1-7)

So if the component is lossless, the condition to be cut-off is Z = j2Z0 for series-through and Y = j2Y0 for shunt-through. The following shows an example using ferrite beads (Figure A1-6). The cut-off frequency in the low range is around 5MHz. At that frequency, it can be seen that |Z|=100Ω, which is double the reference impedance. If the reference impedance is not 50Ω, the result will be different (refer to Figure A1-7).

As an example, a series LCR resonance circuit is plotted on Figure A1-4 in red. The frequency is not directly shown in the fi gure. However, the trace is on the right edge (Γ= 1, open) in low frequency. From that point, it goes clockwise when the frequency increases and reaches back to the right edge again in a high frequency. On the impedance plane, the trace is parallel to the imaginary axis through the point (R, 0).The line is then converted to a circle as shown in Figure A1-3. According to Foster's reactance theorem, reactance is an increasing function of frequency. Therefore, on the Smith chart, the movement is clockwise.The resonance frequency of the series LCR circuit is given by

(A1-4) .

which is the point when the red line intersects with the real Γ axis. The intersection with both constant Q circles shows the half bandwidth, and the Q of the resonance circuit is given by

(A1-5)

where

As shown in this fi gure, the lower the loss (the closer the red line is to the outer circumference of the Smith chart), the narrower the half bandwidth. As a result, Q becomes higher.The Smith chart is used to measure impedance (converted from the refl ection coeffi cient) and to design matching circuits of microwave amplifi ers.

A1-7 The S-parameter for Two-Terminal Components

The following shows how to confi gure 2-port circuits by arranging a two-terminal component, which is characterized by impedance. Figure A1-5 shows the two simplest types of circuit. In practical

63

Figure A1-6 Impedance and S-parameters of ferrite bead

(a)

(b)

100Ω

XR

|Z |

|S11||S21|

The above shows the ideal relationship between impedance and the S-parameter, but when using actual measurement data, care must be taken. This is because the interaction with the GND exists for actual measurements even when the confi guration is the same as Figure A1-5.

A1-8 Cascade Connection

Cascade connection is most often used to construct circuits. The S-matrix SMN for the whole cascade connection of a 2-port device M, and a 2-port device N (the S-matrix for M and N is SM and SN, respectively) is given by

(A1-8)

Where the reference impedance for the connected ports should be equal to each other, the calculation for cascade connection usually uses an F-or T-matrix. However, the formula (A1-8) is convenient when the device is described by using S-parameters and therefore does not require conversion. The input impedance (described by the refl ection coeffi cient ΓIN)

when the port 2 of a device M is terminated can be calculated in case that the device N is a 1-port device (SN11 is its refl ection coeffi cient). Therefore, the refl ection coeffi cient ΓIN is the (1,1) element of (A1-8),

(A1-9) ΓIN = SM11+SM12SN11SM21

1 SM22SN11 .

A1-9 Characteristics of Transmission Lines

Group delay time and characteristic impedance are the characteristics of a transmission line or a fi lter, which is considered as a transmission line.Group delay time tGD using the phase of S21 is defi ned by

(A1-10)

If this value is not fl at to frequency, a signal that contains multiple frequency components such as a digital waveform will be distorted.On the other hand, Characteristic impedance Z0t can be calculated using the Open / Short method ( , where Zopen and Zshort is the input impedance terminated by open and short at the other port, respectively). The input impedance terminated by open or short can be calculated using SN11=±1 in (A1-9).As a result, using S-parameters, the characteristic impedance Z0t can be expressed by

(A1-11)

This calculation is the same as image impedance. This formula is based on the Open / Short method, so it is necessary to keep in mind that accurate calculations can only be made when the frequency is lower than a quarter of the wavelength λ/4. If a coupled line can be decomposed to independent lines by using the adequate

64

impedance is always necessary for acquiring S-parameters (whether by actual measurement or by simulation). Z-parameter (impedance) is usually described with no reference. However, it is possible to describe it using a reference value. For example, when the reference impedance is 50Ω, 200Ω can be described as 4, and 5Ω can be described as 0.1. In this case, the calculation is simple and clear. However, the calculation for the S-parameter is a little more complicated (refer to (A1-3)).50Ω is only a reference value, so it can be changed (renormalization = change of reference impedance). Suppose the S-parameter S is already determined for 50Ω, it is possible to transform it to S-parameter S' for other reference impedances by using

(A1-14)

Where I is the identity matrix, , Z0 and Z0' are the original and new reference

impedance, respectively. It is important to keep in mind that the original S-parameters require all Sij parameters even when you want to know only S'21.

Figure A1-7 Z0 dependency of the S-parameter of ferrite bead

IS11I

IS21I

The arrows for |S11| and |S21| indicate the direction of the reference impedance increase (10Ω→50Ω→100Ω)

modes (for more information about "mode", please refer to A1-11), it is possible to use (A1-11) for each mode. In addition, the characteristic impedance can also be measured by TDR (Time Domain Refl ectometry) using data dependant on time (location).S-matrix St for a lossless transmission line is given by

(A1-12)

Where ,

and t is the electrical length (Unit: Time). If the characteristic impedance of the transmission line is selected for the reference impedance, then ρ=0, and (A1-12) can be simplifi ed to

(A1-13)

Impedance matching causes no refl ection (S11=0). The phase of S21 is rotated according to the electrical length. If the reference impedance in (A1-13) is changed (refer to the next section), it will be returned back to (A1-12).So the denominator in (A1-12) indicates multiple refl ections due to mismatching.

A1-10 Reference Impedance

Reference impedance is an important concept to understand and use S-parameters [4], [5].Usually we simply state that S21 is xxdB. However, to be exact, it should be stated that S21 is xxdB when yyΩ is used as the reference impedance. The reason why the abbreviated expression can be used is that most reference impedance is 50Ω. Still, it is important to keep in mind that the S-parameter is a relative (normalized) value depending on a certain reference value. In other words, reference

65

Figure A1-7 shows S-parameters of ferrite bead with series-through confi guration using three reference impedances of 10, 50, and 100Ω. The smaller the reference impedance, the higher the attenuation; shunt-thru capacitors, which are not shown in the fi gure, give the opposite, namely the bigger the reference impedance, the higher the attenuation.

A1-11 Mixed-Mode S-parameters

Since the late 1990s, high-speed differential (or balanced) transmission systems have been developed for practical use in transmitting digital signals. Although this technology has been used for many years, attention has once again been focused on these systems along with high-speed clocks.A differential transmission system is a system that uses the differential mode (refer to the additional subheading). Therefore, the S-parameter for this system needs to be handled according to the modes, which is referred to as a mixed-mode S-parameter (or modal S-parameter) [5], [7]. Original S-parameter (referred to as a single-ended S-parameter or nodal S-parameter) indicates the response for each port. On the other hand, a mixed-mode S-parameter indicates the response for the sum of two signals (common mode) or the response for the difference of two signals (differential mode).An explanation will be given using a 4-port device that has two input ports and two output ports (Figure A1-8). Ports 1 and 3 make up one group, and ports 2 and 4 the other.

Figure A1-8 4-port S-parameters

2

4

1

3

C1

D1

C2

D2

Mixed-mode S-parameters have the following meanings.• Sccij: Common mode response.• Sddij: Differential mode response.• Scdij, Sdcij: Mode conversion between differential mode and common mode.If the device has good symmetry, the mode conversion should be zero, which means that each mode is independent.It is possible to calculate mixed-mode S-matrix Sγ by using single-ended S-matrix S [5],

(A1-15)

Where

(A1-16)

Here, attention must be paid to the reference impedance. The reference impedance for the common mode and differential

66

References

[1] (in Japanese) Isao OHTA,“Expressions and basic characteristics of electromagnetic wave circuit by using S-parameter”, MWE (Microwave Workshops & Exhibition) '97 Digest, pp.427-436, 1997[2] (in Japanese) Kiyomichi ARAKI,“Analysis and design of electromagnetic wave circuits based on S-parameters”, MWE (Microwave Workshops & Exhibition) '97 Digest, pp.437-445, 1997[3] (in Japanese) Hidetoshi TAKAHASHI, Yasushi FUJIMURA,“Hidetoshi TAKAHASHI's Physics Lecture”, Maruzen, 1990[4] K. KUROKAWA, “Power waves and the scattering matrix”, IEEE Trans. MTT, vol. MTT-13, pp.194-202, 1965 March[5] (in Japanese) Yoshikazu FUJISHIRO, “Evaluation of electronic components using S-parameters”, http://www.tdk.co.jp/tvcl/spara/an-sp06a001_ja.pdf[6] Agilent Technology, “ADS manual” Touchstone is the name of a linear circuit simulator by EEsof(currently Agilent Technologies).[7] David E. BOCKELMAN, William R. EISENSTADT, “Combined differential and common-mode scattering parameters: theory and simulation”, IEEE Tarns. MTT, vol. 43, No. 7, pp.1530-1539, 1995 July

mode is half and twice the reference impedance for the original single-ended S-parameters, respectively. For example, if the reference impedance for original S-parameters is 50Ω, the reference impedance for the common mode is 25Ω, and for the differential mode is 100Ω. If the other reference impedance is needed, it can be changed by using (A1-14).Figure A1-9 shows an example of actual measurements for a common mode fi lter (CMF). It can be seen that this CMF attenuates the common mode signal around 100MHz, but transmits the differential mode signal with little loss in that frequency range.

Figure A1-9 Mixed-mode S-parameters of CMF

ISdd21|

IScc21|

IScd21|

ISdc21|

67

Common Mode and Differential Mode

Suppose there are two conductors (and a GND conductor) that are parallel to each other. When the voltage and the current for each conductor are named as V1, I1 and V2, I2, the common mode voltage Vc and Current Ic and the differential mode voltage Vd and current Id are defi ned as the following (International electrotechnical vocabulary in EMC, IEC60050-161:1990, JIS C0161: 1997)

· Vc: Average voltage for each conductor Vc:=(V1+V2)/2· Ic: Total current for each conductor Ic=I1+I2· Vd: Voltage between two conductors Vd=V1-V2

· Id: Half of the current difference for each conductor Id=(I1-I2)/2

The common mode indicates the sum of signals, while the differential mode displays the difference between signals. The current in differential mode fl ows backwards (anti-phase) through two conductors. Therefore, GND is not directly connected (for that reason, it is referred to as normal mode). On the other hand, the current in the common mode fl ows in the same direction (in-phase) through two conductors. Consequently, the current fl ows through the GND conductor (or through another area) and then returns (hence this is referred to as an earth circuit). The common mode is also referred to as asymmetrical (or vertical, as in vertical electrical current) or longitudinal, and the differential mode is also referred to as being symmetrical (or horizontal).

Appendix 2

Classifi cation of Electronic Components

70

Electronic components are passive components that are used for electronic circuits. In a limited sense, these do not include sound-, light-, or mechanical-related components or electromechanical components such as a switch or connector. When electronic components are sorted according to their usage, they can be divided into “resistive components” and “others (reactive components)” (Table A2-1). The latter components are lossless, so they are used in order to control signal or electric power. Components that are used for analog high-frequency circuits such as balun, coupler, circulator and so on are designed to handle a single frequency and to basically control signal fl ow. On the other hand, components that are used for digital circuits such as capacitors, inductors, and three-terminal fi lters with combinations of capacitors and inductors are designed to handle multiple frequencies and are used as fi lters. Of course, capacitors and inductors have multiple purposes and can be used for other situations. For more information on the functions and usages of electronic components, refer to Table A2-2."EMC components" is a general term for electronic components used to control EMC. These include the kind of fi lter and varistor (this can also be considered a fi lter for voltage) shown in Table A2-1. Therefore, EMC components do not refer only to special components. There is no clear distinction between inductors and beads. However, a bead is basically a loss in the high frequency range and is commonly used because their loss is effective at preventing EMC (energy can be absorbed). On the other hand, an inductor is used in the relatively low frequency range where high inductance is needed.Chip components (SMD components) do not include leads and are connected directly to substrates. Usually, their size is described using a 4-digit number. For example, "1005" indicates a component

that is 1.0mm length × 0.5mm width.Electrical characteristics for electronic components can be evaluated using impedance and / or S-parameters. Impedance applies to two-terminal components. It is also possible to use impedance for the characteristics of multi-terminal components if those terminals can be combined to form a two-terminal component, e.g. the common mode fi lter (CMF) and transformer. These characteristics can be described using several kinds of impedance by changing connections. Components that require a GND are characterized by S-parameter because impedance is diffi cult to use. If a component that is usually evaluated using impedance is attached to a GND, evaluation by using S-parameters is possible.

Table A2-1 Representative electronic components

Category Electronic component

Resistive componentResistorThermistorVaristor

Reactive component

Control signals

Transmission linePower splitterBalunCoupler, Isolator, Circulator

Filter

CapacitorInductive components Inductor, Bead Transformer, Common mode fi lterThree-terminal fi lter

Classifi cation of Electronic Components

71

NTC

Balun

Table A2-2 Functions and usages of various electronic components

Electronic component Exterior Type Function Usage

ResistorThick fi lm (Cermet) Thin fi lm (Metallic fi lm)

Z=RDivides voltage and current /Limits the current / Detection / Termination (Load) / Filter

NTC Thermistor Ceramic Z=R(T) Temperature measurement

PTC ThermistorPlastic / Ceramic

Z=R(T) Over current prevention (Fuse) / Heater

VaristorZnO TypeSrTiO3 Type

Z=R(V) Over voltage prevention

CapacitorCeramic[Hε,Lε] Electrolytic type[Al,Ta], Film

Q=CVZ=1/jωC

Bypass (Decoupling) / Smoothing / Coupling / Filter (RC,LC) / Time constant /Matching / Phase compensation

InductorAir core, Ferrite [Mn,Ni]Metallic

Z=jωL Choke / Decoupling / Filter / Matching

Beads Ferrite Z=R(f)+jX Noise control

TransformerFerritePiezoelectric

➞

DC isolation / Common mode rejection /Balance-Unbalance conversion / Change polarity /Up- or Down-convert voltage / Transform impedance

CMFWinding, Thin fi lmMulti-layer

Scc21=Scc21(f) Common mode noise control

Filter, DuplexerLC, PiezoelectricDielectric

Sij=Sij(f) Signal fi ltering

Power splitter - S =0 α βα 0 0β 0 0

Split and / or combine signal

Balun - S =0 α -αα 0 0-α 0 0

Balance-Unbalance conversion

Coupler - S = 0 tUU 0

Signal monitor / Separate incidence and refl ection signal

Isolator - S =0α 0

0 Unidirectional(Protect for refl ection signal), Mismatch relief

Circulator - S =0 αα 0 00 α 0

0Antenna sharing, Isolator, Branch signal

Notes

Data and simulation results from SEAT do notguarantee product characteristics.

TDK is not responsible for any damages related to SEAT orthe contents of this manual.

Companies and product names contained in this manual arethe registered trademarks of their respective companies.

Screens and data that appear in this manual areaccurate as of May 2010.

The contents of this manual may be changed due to revisionwithout prior notifi cation.

Therefore, content accuracy can not be guaranteed.

"SEAT" Tutorial I-DA002E-F

April 2005 First EditionJune 2010 Seventh Edition

Issued by TDK Corporation 103-8272 1-13-1 Nihonbashi, Chuo-Ku, Tokyo

Planning / Editing TDK Corporation Application & Analysis Center TDK-EPC Corporation Electronic Components Sales & Marketing GroupDesign TDK Design Inc.

● If you wish to reprint or copy the contents of this manual, please contact me person in charge for editing shown above.