The Fundamental Technical Knowledge of Passive Components

Transcription

1 The Fundamental Technical Knowledge of Passive Components for Windows version

2 - Chapter 1-1 Capacitor

3 Impedance Characteristics of Capacitor Impedance equivalent circuit with capacitor is the same as the RLC series model. Elements in Capacitor Changes in Frequency Changes in Element ESR Impedance Impedance ESR: Increase ESR is constant Frequency Frequency ESL Impedance ESL increases Frequency Impedance ESL: Decrease Frequency Capacitance Impedance Impedance Cap. : Increase Capacitance decreases Frequency Frequency What happens to the impedance level when connected in series?

4 Impedance Characteristics of Capacitor Impedance for series connection Impedance with different elements Impedance depends on capacitance Impedance depends on ESL Impedance インピーダンス [Ω] Resonance Point Impedance depends on ESR Frequency 周波数 [MHz] インピーダンス Impedance [Ω] Cap. : Increase Resonance Point Cap. : Increase, ESL: Increase ESR: Decrease ESL: Decrease Frequency 周波数 [MHz] At resonance point, no impedance for Capacitor & ESL (Impedance for ESR only) The frequency at resonance point depends on Capacitor & ESL Impedance characteristics vary depended on each element.

5 Impedance Characteristics of Capacitor ESR varies depended on frequency Frequency characteristics for different type of capacitors Impedance,ESR[Ω] Impedance,ESR Freq.-Temperature Characteristic R Z インピーダンス ESR [Ω] Impedance Ta 47μF ESR Ta 47μF Z NEO 47μF ESR NEO 47μF Z SPCAP 47μF ESR SPCAP 47μF Z JM432BJ476MM MLCC47μF ESR ESR JM432BJ476MM MLCC47μF Z Z SDK47μF ESR SDK47μF Z Frequency[KHz] RLC Series Model ESR independent from frequency ESR actually varies 周波数 [khz] Frequency RLC varies depended on capacitor s material, structure and case size Frequency characteristic varies depended on the type of capacitor, especially on ESR.

6 Reliabilities of Multi-Layered Ceramic Capacitor 1. Operational condition comparison chart for Circuit MLCC Ta Cap. Al Cap. Application Problems Ripple CU. Heat Solvent Polarity De-rating Limitation Resistance Resistance No Yes Yes Layout Polarity exam When mounting Reverse voltage Consideration Operational limitation for rated voltage (70~50%level) Ceramic Capacitor Dielectric: Barium Titanate Have margin capacity for ripple current Less reliable associated from self heating Limitation for reflow molding and degrading advancement Liquid solution flooding except block structure MLCC Loading Test Al capacitor: decreasing in capacitance from electrolysis loss Ta capacitor: diffusion of Ag, short circuit from degrading of insulating layer Breakdown Voltage (V) Leaded <Surface mounted> Vertical style Horizontal style Leaded Al Capacitor What s Electrolytic Capacitor? Dielectric Al foil Al foil Electrolytic paper Dielectric (Ta 2O 5) MnO 2 Tantal (Al 2O 3 ) La Ta Capacitor Graphite Argentum paste Solder Electrolytic paper Al foil Da Ra La Dk Ca Ck Lx Rk Da Ca Ra Lx Al foil Electrolysis solution Ca, Ck: positive/negative pole cap. Da,Dk: rectification from negative pole s oxidization coating La,Lk: Inductance for +,- leads R: resistance of electrolsis solution and paper Ra,Rk: Inside resistance of forward direction from +,-poles oxidization coating <Surface mounted> Breakdown voltage level comparison: rated voltage 10V MLCC 100 Ta Capacitor Electrode: Ni 0 Forward direction Backward direction 212F F BJ BJ225 10uF 4.7uF 10uF 1uF 2.2uF

7 Characteristics Comparison for the Different Type of Capacitors Frequency Characteristics インピーダンス ESR [Ω] Impedance Ta 47μF ESR Ta 47μF Z NEO 47μF ESR NEO 47μF Z SPCAP 47μF ESR SPCAP 47μF Z JM432BJ476MM MLCC47μF ESR ESR JM432BJ476MM MLCC47μF Z Z SDK47μF ESR SDK47μF Z ESR varies greatly depended on each type of capacitors. Al>Ta>Functional Ta>Functional Al>ML The lower ESR becomes, the lower the impedance for high frequency gets Frequency 周波数 [khz] Al>Ta>Functional Ta>Functional Al>ML MLCC has superior frequency characteristics. The most competitive merit

8 Characteristics Comparison for the Different Type of Capacitors Ripple Current Characteristics Ripple current characteristics for the different type of capacitors Ripple current ESR Capacitor Heat ESL Heat Electrical energy is converted to heat when current goes through resistance. Capacitor Electrical energy is converted to heat when ripple current (AC) goes through capacitor. (DC does not go through it) Heat shortens capacitor s durability. Temperature rise (degree) リップル電流対部品温度上昇の比較 Temperature rise characteristic due to ripple current 積層コン MLCC47uF 47μF タンタル Tant.Cap47uF 47μF POSCAP100μF POSCAP100uF リップル電流 (Arms) Ripple current(arms) Given the same amount of calorific power, ripple current goes through MLCC the most because of its low ESR. Operational recommendation of heat release value for MLCC is within 10. There is no limitation of allowed ripple current for MLCC. Operational recommendation of heat release value for electrolytic capacitor is within 5. Allowed ripple current is regulated by makers.

9 The Basic Knowledge of Circuits

10 The Functions of Bypass (decoupling) Capacitor The Role of Bypass Capacitor Noise + Load current Load Current Necessary Characteristics for Bypass Capacitor It has low impedance. (low prevention of an electric current) Power supply line Noise Current To connect the noise current to the earth (grounding) IC The principle of operation for Bypass Capacitor It electrifies an electric current well. It efficiently grounds the noise current. It effectively decreases the noise current. DC does not go through the capacitor (Impedance: ) DC is supplied directly to IC AC (noise) does go through the capacitor Noise: more Low Impedance Noise: less High Impedance AC (noise) is grounded Noise Suppression Stabilize IC operation Impedance Low High Noise effect of decreasing More effective Less effective

11 The Functions of Bypass (decoupling) Capacitor Impedance,ESR[Ω] Selection Criteria for Capacitor Impedance,ESR Freq.-Temperature Characteristic Increasing in noise suppression effectiveness Frequency[KHz] R Z Decreasing in noise suppression effectiveness Maximum level for noise suppression effectiveness Several kinds of Noise Frequencies Replacement of Ta capacitor by Bypass Capacitor Change product name 100 to MLCC + capacitance Impedance(Ω) インピーダンスの比較 Impedance Comparison タンタル Ta10uF 10μF タンタル Ta47uF 47μF LMK212F475ZG LMK316F106ZL LMK212BJ225KG EMK325BJ106KN Frequency(kHz When the frequency is over 10kHz, the impedance of MLCC is lower than that of Ta capacitor. Effectiveness of reduction in high frequency noise for MLCC is more superior than that of Ta capacitor. Select a Capacitor based on noise frequency needs to be eliminated It enables to replace Ta capacitor with a smaller value of MLCC.

12 The Functions of Backup Capacitor Load current to IC Load current doesn t stay constant. Power line for high-speed load changing Large load current is The current can t flow quickly needed. to IC quickly enough. Load current: small IC IC IC IC Load current: large Line voltage Line voltage Operating at low-speed High-speed load change Operating at high-speed When IC s operational speed changes rapidly, large load current is quickly needed. Load current Low-speed operation High-speed operation Line voltage can t be maintained, therefore voltage is dropped. Voltage dropped Line voltage IC Circuit voltage, Load current Low-speed operation Line voltage decreases below the required operational voltage for IC. High-speed operation Minimum required operational voltage for IC Time Time The IC stops its operation.

13 The Functions of Backup Capacitor The Role of Backup Capacitor Electric current delays Making up for electric current shortage Capacitor s actual (considering equivalent circuit) This is a simplified version, so disregard ESL Voltage dropped Line voltage IC Maintaining Line voltage IC ESR Capacitor Voltage dropped by electric current Voltage dropped by discharge current Line voltage dropped Line voltage, needed load current, Discharge current from Capacitor Low-speed operation High-speed operation Minimum required operational voltage for IC Line voltage Voltage fluctuation occurs when capacitor charging Voltage dropped by ESR Voltage dropped by electric discharge Voltage risen by capacitor charging Voltage risen by ESR Time Keeping the minimum required operational voltage for IC Maintaining stable operation Capacitor and ESR decide the amount of voltage dropped

14 The Functions of Backup Capacitor Power Supply Voltage= 5V Experimental circuit R = 1Ω Current probe To oscilloscope Load resistance R=5Ω Rating Capacitor 2SK2684 Pulse generator 1945 (NF) Experimental result for Capacitance and ESR Ripple LMK432BJ226MM Voltage of LMK432BJ226MM のリップル電圧 20mV/Div 20mV/Div Ripple タンタルVoltage 100μF of のリップル電圧 100uF Ta Cap Voltage ESR による電圧変動 fluctuation by ESR MLCC 47µF 7 Switching frequency = 1000KHz Voltage 容量による電圧変動 fluctuation by capacitance ESR comparison 10 1 ESR の比較 MLCC 積層コン 22uF 22μF Ta Cap タンタル100uF 100μF High Value Low ESR 1μS/Div 1μS/Div The fluctuation band of line becomes narrower. ESR(Ω) 周波数 (KHz) Frequency (KHz) Merits of MLCC It enables to replace Ta capacitor with a smaller value of MLCC. The effectiveness of MLCC s voltage fluctuation depressing effect is greater than that of Ta capacitor.

15 Application Examples for Backup Capacitor MLCC 10uF 22uF 47uF 100uF LMK325BJ106MN( 積層コンデンサ 10μF) LMK432BJ226MM( 積層コンデンサ 22μF) JMK432BJ476MM( 積層コンデンサ 47μF) JMK550BJ107MM( 積層コンデンサ 100μF) JMK316BJ106ML(10uF) JMK325BJ226MM(22uF) JMK432BJ476MM(47uF) JMK550BJ107MM(100uF) 50mV/Div 50mV/Div 50mV/Div 50mV/Div 2.5μS/Div 2.5μS/Div 2.5μS/Div 2.5μS/Div Ta Cap タンTa タルコン Cap デン10uF サ10μF タンタルコンデンサ22μF タンタルコンデンサ47μF タンタルコンデンサ100μF Ta Cap 22uF Ta Cap 47uF Ta Cap 100uF 50mV/Div 50mV/Div 50mV/Div 50mV/Div 2.5μS/Div 2.5μS/Div 2.5μS/Div 2.5μS/Div OS-CON OS コン 10μF OS コン 22μF OS コン 47μF OS コン 100μF OS-CON 10uF OS-CON 22uF OS-CON 47uF OS-CON 100uF 50mV/Div 50mV/Div 50mV/Div 50mV/Div 2.5μS/Div 2.5μS/Div 2.5μS/Div 2.5μS/Div

16 The Basic Knowledge of Power Supply Circuit

17 Series Regulator (3 Terminal Regulator) Circuit operation (water gate model) Load current fluctuation Controlling element (transistor) Controlling element (transistor) Input voltage Output voltage Load current Input voltage Output voltage Load current Producing output voltage by lowering certain amount of input voltage Step-down power supply Controlling water gate to keep the water level constant Controlling load current with transistor Output voltage stays constant.

18 Series Regulator (3 Terminal Regulator) Circuit structure Input voltage > Output voltage Regulator IC Effects of input capacitor Add alternate current to input voltage purposely to measure input current amount with or without input capacitor Input Capacitor Output Capacitor Consisting of IC, input and output capacitors. IC IC Function of input capacitor Noise + Load current Load current Without capacitors With capacitors (MLCC) Noise current Connecting the line noise to the ground. IC Input Voltage Vin Vertical: mv Horizontal: u sec Same as the function of Bypass Capacitor Input voltage is stabilized as input capacitor is connected.

19 Series Regulator (3 Terminal Regulator) Function of output capacitor Unable to supply current immediately IC Voltage dropped Line voltage IC Cover the current shortage Keeping line voltage Effects of output capacitor Measuring the voltage fluctuation when load change is occurred with/without output capacitor. Load Current Iout IC IC Supply current to control voltage fluctuation for rapid load change Same as the function of Backup Capacitor Output fluctuation ΔVout Without capacitors With capacitors (MLCC) Output voltage is stabilized as output capacitor is connected.

20 Step-Down Converter Circuit operation (water gate model) Producing output voltage by lowering input voltage with transistor Input voltage Controlling element (transistor) Output voltage Load current Transistor for switching power supply has only ON or OFF signal. Switching operation Controlling output voltage by switching Turn-on cycle Constant Time to be ON Changes Turn-on cycle Changes Time to be ON Constant PWM method PFM method Input voltage Controlling element (transistor) Output voltage Load current Turn-on cycle of the switch Switching frequency Control ON ON ON Control ON ON ON PWM Time PFM Time

21 Step-Down Converter Circuit structure Choke coil Operation of input capacitor Ripple current Ripple current flows into input capacitor. FET1 Control IC FET2 FET (2) heat heat Heat generated by ESR Necessary characteristics of input capacitor Input capacitor Input side current Input current FET1 ON FET1 ON FET1 ON Output capacitor Time Large amount of alternating current (ripple current) flows. High tolerance for ripple current Example: Permissible ripple current of a capacitor is 1A. Ripple current: 6A 1A 1A 1A 1A 1A 2A 2A 2A 1A Example: Permissible ripple current of a capacitor is 2A. Ripple current: 6A 6 capacitors 3 capacitors Reduced

22 Step-Down Converter Output side operation Choke coil Points of output voltage to remember Keeping higher voltage than the lowest operating voltage of load IC. Ripple voltage Voltage Input voltage ON ON ON Output capacitor Voltage Output voltage The lowest operating voltage Rapid load voltage fluctuation Rated output voltage Keep the band of ripple voltage within the rated value. Time Input voltage is controlled by an on-off switching. Time It is smoothed with a choke coil and an output capacitor. Ripple voltage is included. The lowest operating voltage Rated output voltage Control voltage drop by rapid load voltage fluctuation

23 Step-Down Converter Factor for determining voltage drop by rapid load voltage fluctuation Operation at rapid load change Same as Backup Capacitor Necessary characteristics for capacitor when rapid load fluctuation occurred High capacitance Supply capacitor of high electronic charge Low ESR Reducing voltage drop when supplying electronic charge High Value MLCC Suitable Factor for determining ripple voltage ESR Capacity Repeating an on-off switching signal Charge and discharge are repeated with output capacitor. Voltage is fluctuated by current flowing in and out. When charging Charging Current Voltage rise Charging Voltage rise Ripple voltage Repeat When discharging ESR Capacity High capacitance and low ESR reduce ripple voltage. Discharging current Voltage drop Discharging Voltage drop

24 Charge Pump (Boost) Operation of charge pump (image) Charging 2 capacitors separately V Charging C1 V V Charging C2 V Output capacitor (smoothing capacitor) Circuitry of charge pump (example: double boost) Input capacitor In IC Out Capacitors for charging Output capacitor Connect C1 C2 V V 2V Load Required characteristics of capacitor Charging capacitor and output capacitor Lowering voltage fluctuation occurred by charging/discharging Connecting charged capacitors Output double amount of voltage than input Smoothing with output capacitor (Switching) Output voltage is determined by the number of capacitors connected. (integral multiple) Backup Capacitor Same as step-down output capacitor High capacitance and low ESR are required.

25 Summary Comparison of Various Input Capacitors Measuring the noise absorption and the output voltage fluctuation by adding sine wave on input line 1000 Vertical mv, Horizontal µsec コンデンサ未挿入 Without Capacitor 入力変動 ΔVin Output 出力変動 fluctuation ΔVout Input fluctuation Vs:1Vrms 7.5V Z1 Z 2 Δ Vin = Vs Z1+ Z 2 Regulator Vs Z2 ΔVin IC ΔVout IC used:njm78l05(jrc) Capacitor used:lmk212bj105kg, Ta1uF, A11uF (Z1:Line impedance) Capacitor (Z2) has low impedance. Effect of noise suppression: large Constant IC input voltage Input fluctuation of 1Vrms Output fluctuation of 35Vrms Input capacitor inserted Vertical mv, Horizontal µsec 入力コンデンサ挿入時の入力変動 With Capacitor ΔVin Al Cap 電解 1μF Ta Ta Cap 電解 1μF MLCC 積層 1μF MLCC is excellent in noise suppression (low impedance). 500 Z ESR [Ω] Frequency Characteristics 各種コンデンサ周波数特性 (1μF) ML R ML Z Ta R Ta Z Al R Al Z Freq. [khz] Vertical mv, Horizontal µsec 入力コンデンサ挿入時の出力変動 With Capacitor ΔVout Al Al Cap 電解 1μF Ta Ta Cap 電解 1μF MLCC 積層 1μF Output fluctuation becomes smaller as IC input voltage stays constant. MLCC has lower impedance than that of Ta for a wide range of frequency. MLCC is suitable for input capacitor

26 Summary Operation Analysis of Output Capacitor Observation of output voltage fluctuation ESR [Ω] Frequency Taコンと積層コンの Characteristics ESR- 周波数特性比較 Comparison 1000 JMK212BJ475KG 100 Ta4.7μF Regulator IC Iout IC used: R1112N331B (Ricoh) Input Cap: LMK212BJ225KG Input V: 5V Switching frequency: 100Hz Load current: 150mA Freq. [khz] Vout Waveform observation: Iout, Vout (Observing by the type of output capacitors) Load 負荷電流 Current Iout ma Load 負荷電流波形 Current Waveform Time 時間 μsec ESR:Large 0 Ta 4.7μF Variable ESRの変動分 ESR: Large : 大 Vout 出力電圧変動 Fluctuation ΔV mv Time 時間 μsec -100 ESR:Small Using output capacitor with low ESR reduces the output voltage drop when load fluctuation occurred Vout 出力電圧変動 Fluctuation ΔV JMK212BJ475KG Variable ESRの変動分 ESR: Small : 小 出力電圧変動 Vout Fluctuation Without 未挿入 Capacitor Ta 4.7uF Ta 4.7μF JMK212B475KG Vertical mv, Horizontal µsec MLCC with low ESR is well-suitable for output capacitor.

27 Development Method Direction for ML Lineups and Proposals Market demand Circuit segment Capacitor application segment Required performance Digital circuit Analog circuit Amplifier Arithmetic Oscillation Modem Logic Digital High frequency Power supply Power supply Audio Others Focusing on impedance and ESR characteristics Decoupling Backup Smoothing High pressure Filter Coupling Time constant, Resonance Focusing on the stability of real capacitance, temperature and bias It is for circuit noise suppression and often used in digital circuits. Low Impedance, Low ESR MLCC with Y5V characteristic and uF is best suited It may also be used for a circuit with large load change (CPU), stability of power line and protection of IC. Low ESR, Low ESL, Low Impedance MLCC with characteristics of Y5V,X5R,X7R and uF is best suited. It is for in/output of power supply circuit and more used as the miniaturization of equipment. Real capacitance, Low ESR, Low ESL, Low Impedance Rated Voltage and Reliability MLCC with characteristics of X5R, X7R and 1- tens of uf is best suited. It is for amplifier, arithmetic, modem and filter circuits. Stability of capacitance temperature and bias is important. Temperature compensating dielectric type MLCC is best suited. (CFCAP, TC type multilayer)

28 Proposal for Bypass Capacitor Replacement proposal for high capacitance Ta or Al electrolysis with ML 0.1uF Common Case Example Ta or Electrolysis Multilayer 0.1uF 電解コン 22μF+ Impedance 積層 0.1μF Characteristics のインピーダンス特性 インピーダンス Impedance [Ω] Electrolytic 電解コン 22μF+ cap 22uF 積層 + 0.1μF MLCC 0.1uF Electrolytic 電解コン 22μF cap 22uF MLCC 積層 0.1μF 0.1uF Replaced only by a single High Value MLCC High Value MLCC Replaced only by a single MLCC Frequency 周波数 [KHz] Impedance for high frequency decreases. High frequency characteristic is advanced. 大容量積層コンデンサのインピーダンス特性 Impedance Characteristics インピーダンス Impedance [Ω] Electrolytic 電解コン cap 22uF 22μF+ + MLCC 積層 0.1μF 0.1uF 1000 MLCC 4.7uF 積層コン F 特 4.7μF MLCC 10uF 積層コン F 特 10μF Frequency 周波数 [KHz] Wider low impedance range compared with parallel use.

29 - Chapter 2-2 Inductor

30 Impedance of Inductor and Capacitor Inductive Reactance & Capacitive Reactance Ohm s law: (Alternate voltage)=(impedance) (Alternate current) Impedance of pure inductor: inductive reactance: it increases as frequency increases. Inductance: L Alternate power supply Frequency : f Voltage magnitude : VO V=V0 exp(jωt) According to the Ohm s law, the impedance of pure inductor is proportional to frequency and inductance. V=L di/dt Solving for V: V0=j2πf L Impedance is equal to:z=xl=2πf L インピーダンス Impedance Inductance: High Inductance: Medium Frequency 周波数 Inductance: Low Impedance of pure capacitor: capacitive reactance: it decreases as frequency decreases. Frequency : f Voltage magnitude : VO V=V0 exp(jωt) Alternate power supply Capacitance :C According to the Ohm s law, the impedance of pure capacitor is inversely proportional to frequency and capacitance. V=1/C idt Solving for V: V0 = 1/(j2πf C) Impedance is equal to: Z = Xc = 1/(2πf C) インピーダンス Impedance Capacitance: High Capacitance: Medium Frequency 周波数 Capacitance: Low

31 Usage of Inductor and Capacitor: Low-pass Filter and High-pass Filter Impedance of inductor: It increases as frequency increases. Impedance of capacitor: It decreases as frequency increases. Typical characteristic of low-pass filter Typical characteristic of high-pass filter IN OUT IN OUT Gain GND In case of low frequency, inductor s low Z: passing-through capacitor s high Z: passing-through instead of dropping to the ground Frequency 周波数 In case of high frequency, inductor s high Z: blocked capacitor s low Z: dropping to the ground Gain Gain In case of low frequency, inductor s low Z: dropping to the ground capacitor s high Z: blocked GND In case of high frequency, inductor s high Z: passing-through instead of dropping to the ground capacitor s low Z: passing-through Frequency 周波数

32 Series Circuit Series Resonance and Parallel Circuit Parallel Resonance of Inductor and Capacitor Impedance of inductor: It increases as frequency increases. Impedance of capacitor: It decreases as frequency increases. Series circuit of pure inductor and capacitor: Series resonance Series circuit: Basically addition Parallel circuit of pure Inductor and capacitor: Parallel resonance Parallel circuit: Basically an electric current flows in lower impedance. Capacitor impedance インピーダンス Impedance Inductor s impedance At resonant frequency: zero Frequency 周波数 Impedance of series circuit Capacitor s impedance インピーダンス Impedance Inductor s impedance Frequency 周波数 Impedance of parallel circuit At resonant frequency:

33 Application of Inductor and Capacitor Band-pass Filter and Trap Filter Impedance of series circuit: Lowest at frequency resonance point Impedance of parallel circuit: Highest at frequency resonance point Typical characteristic of trap filter Typical characteristic of band-pass filter IN GND OUT Series circuit: low Z at resonant frequency: dropping to the ground IN GND OUT Parallel circuit: high Z at resonant frequency: passing-through instead of dropping to the ground Gain Gain Frequency 周波数 Frequency 周波数

34 Real Characteristics of Inductor Self-Resonance Point Characteristic Multilayer inductor Typical impedance characteristic of existing inductor ~similar to the typical impedance characteristic of LCR parallel circuit~ Ex) Stray capacitance existed between internal and external electrode Wound chip inductor インピーダンス Impedance 周波数 Frequency Ex) Stray capacitance existed between winding wires Inductor for the low frequency side, capacitor for the high frequency side and at resonance point, impedance is limited.

35 Application Ex. using Self-Resonance Characteristic of Inductor Trapping Formulation by Low-pass Filter Example of Low-pass filter Inductor A: impedance characteristic Inductor B: impedance characteristic IN GND OUT Impedance インピーダンス It has a sharp peak point at a resonance frequency. Impedance インピーダンス Same inductance as inductor A, but its impedance is lower than that of A s. Frequency 周波数 Frequency 周波数 Filter characteristic of pure inductor Inductor A in use Inductor B in use Trap-less Gain Gain Trapping resulted from the sharp peak point Gain Transmitting characteristic deformed Frequency 周波数周波数 Frequency Frequency 周波数 This self-resonance characteristic is proactively implemented for a filter circuit application, and therefore this unique characteristic needs to be considered for both replacement and downsizing applications.

36 Real Characteristics of Inductor Lost Elements and Q Characteristic ML inductor Wound chip inductor Resistance elements (Summation of loss) Inductor s Q factor Impedance of pure inductor: Inductive reactance R XL Print internal electrode on sheet made of core material Inductive reactance Wind up wire around core Q = Resistance elements Core materials: Hysterisis loss, Eddy current loss, dielectric material loss and more Internal electrode: DCR, resistance loss in high frequency zone originated from skin effect and more Pure inductor has no loss at all. Q factor is an approximation value which expresses how close an inductor is to be a pure inductor. The larger the Q factor an inductor has, the purer the inductor becomes on circuit.

37 Q Factor and Filter Characteristics of Inductor Example of How the Difference in Q Factor Influences Trap-Filter Characteristic Example of trap filter Series resonance of inductor and capacitor Inductor A: Q factor characteristic Inductor B: Q factor characteristic IN OUT Q Q Low Q factor GND Filter characteristic example of pure inductor Frequency 周波数 Inductor A in use Frequency 周波数 Inductor B in use Gain Gain Gain Not enough trap Frequency 周波数 Frequency 周波数 Frequency 周波数 In case of resonance circuit with capacitors, generally inductor s Q factor characteristic has huge influence on the circuit.

38 Q-Value and Matching Characteristics Example of How the Difference in Q-value Q Influences Matching Characteristic Example of matching circuit Matching for amplifier and antenna Inductor A: Q factor characteristic Inductor A: Q factor characteristic Q Q Low Q factor Frequency 周波数 Frequency 周波数 Example of matching design with pure inductor Inductor A in use Inductor B in use With the inductor, impedance is matched at the center of the chart. Fit the design Shifted off the center of the chart Amplifier s characteristic: starting point In case of matching circuit, generally inductor s Q factor characteristic has huge influence on the circuit.

39 Coffee Break Q Factor of Inductor and Tan δof Capacitor Q factor of inductor inductor s loss elements Tan δof capacitor capacitor s loss elements Resistance elements (summation of loss) Impedance of pure inductor: inductive reactance Resistance elements (summation of loss) Impedance of pure capacitor: Capacitance reactance R XL R Xc Q = Inductive reactance Resistance elements Tan δ = Resistance elements Capacitance reactance Q factor is an approximation value which expresses how close an inductor is to be a pure inductor. The larger the Q factor an inductor has, the purer the inductor becomes on circuit. Tan δ is a value which explains how far a capacitor is from being a pure capacitor. The smaller the tan δ a capacitor has, the purer the capacitor becomes on circuit.

40 Real Characteristics of Inductor Example of DC Bias Characteristic Example of inductor s DC bias characteristic Example of impedance characteristic インダクタンス Impedance In case of magnetic-material core which has the magnetic saturation characteristic, inductance is lowered by increasing in DC bias current. Example of an inductor which has a strong characteristic against DC bias Example of an inductor which has a weak characteristic against DC bias DC Bias バイアス電流 Current Impedance インピーダンス Impedance インピーダンス 周波数 Frequency Impedance gets lowered as inductance is dropped by magnetic saturation. An inductor which has a strong characteristic against DC bias can maintain high impedance level (vice versa). Generally, an inductor is selected based on a margin level for both required inductance and impedance under operational circumstances. Frequency 周波数

41 Example of the Influence on Inductor s s DC Bias Characteristic in use of Power Supply Choke Example of power supply choke circuit Capacitor: Bypass to the ground ON/OFF noise IC Load fluctuation Impedance increased by high frequency Inductor: Blocked by impedance Bypass improved インピーダンス Impedance Inductor A: Impedance characteristic A strong characteristic against DC bias and maintain high impedance Inductor B: Impedance characteristic Impedance インピーダンス A weak characteristic against DC bias and unable to keep high impedance Bypass characteristic of capacitor only Frequency 周波数 Inductor A in use Improved bypass characteristic at high frequency range Frequency 周波数 Inductor B in use Inferior bypass characteristic In case of power supply choke application, it should take full advantage of impedance characteristic in terms of designing of bypass circuit. Since impedance characteristic is degraded by DC bias, it should be paid attention to see if the required value left under operational circumstances comparing with self-resonance characteristic.

42 Example of the Influence on Inductor s s DC Bias Characteristic of Power Supply Switching Circuit Application Example of step-up power supply circuit Inductance: L General relationship between DC bias characteristic and Is DC Input Vin Vs Vs:ON Is DC Output Vout While Vs turned on, Is flows to IC and then voltage is raised by inductor. When Vs being off, it is added onto the input DC and then Output DC is up-converted. When Vs is being on, Vin = L dis/dt, solving for this Is = Vin / L t Is gradually increases as Vs turned on, it increases rapidly with small inductance. It is important to know of the tolerance current when selecting an inductor for the power supply circuit. OFF ON OFF ON Impedance インダクタンス Current IC を流れる電流 (Is) flows :Is into IC バイアス電流 DC Bias current Switching IC broken down As DC bias current increases, the inductance starts decreasing. DC bias current passes at some point, inductance drops suddenly. When DC bias current passes the tolerance current, (for the worst case scenario) the switching IC is broken down. Is 及び and Vs Is Is increases as times goes on. Is increases even faster with small inductance. 時間 Time 時間 Time Switching interval is shortened by high frequency power supply IC, and therefore large inductance is no longer needed for IC. Addition to this, flat DC bias characteristic isn t ideal for all kinds of circuit. It would be better to match a specific DC bias characteristic with IC and power supply demand.

43 Coffee Break The Charging and Discharging Mechanisms of Capacitor Charging mechanism Increasing electric charge Voltage raised +Q -Q Capacitor Electric current Battery Apply voltage to a capacitor, electronic charge is built up in the inside of capacitor. On the other hand, when both sides of external electrodes are short-circuited, the capacitor discharges the built-up electronic charge. Decreasing electric charge Discharging mechanism +Q Voltage dropped -Q Capacitor Electric current A time-varying electric charge induces electric current. -I = dq/dt Capacitance is the constant of proportion derived from the relationship between the quantity of electric charge and voltage. Q = C V The relationship among voltage, electric current and capacitance -V = 1/c idt or I = C dv/dt The equivalent relationship for inductor -V = L di/dt The quantity of electronic charge is proportional to voltage. (In case with inductor, an electronic current creates magnetic flux. The quantity of magnetic flux is proportional to electronic current.) Capacitor s capacitance is the constant of proportion between the quantity of electronic charge and voltage. (In case with inductor, inductance is the constant of proportion from magnetic flux and electronic current. A time-varying electric charge or discharge induces electric current. In case with inductor, a time-varying magnetic flux induces electric voltage.

44 - Chapter 3 - Electro-Magnetic Compatibility (EMC)

45 The Different Types of Noise Contents Countermeasure components Radiation noise Conduction noise (noise terminal voltage) Ripple voltage (current) It leaks out as an electromagnetic wave. The sources are signal line and power line. There are restrictions in countries. (VCCI, FCC, CISPR, EN, etc.) It runs through DC power line, i.e. switching noise, etc. The sources are DC-DC power supply converter, etc. A fluctuation by voltage drop occurred when IC operates. It becomes a problem at power line with high power consumption for CPU, etc. Mainly ML Ferrite Chip Beads BK series, Rectangular Ferrite Chip Beads (High Current) FB series M type. Resistors and capacitors may also be used. Mainly Surface Mount High Current Inductors NP series, Wound Chip Inductors LB series and such ferrite components and capacitors for DC- DC, etc. Mainly capacitors Electrostatic Surge noise A discharge phenomenon, which is caused by friction charge. It causes element destruction and malfunctions. Instantaneous high voltage and current. It is occurred by natural phenomenon (eg. thunderstorm), inserting and removing a cable, etc. Mainly Chip Varistors and Diodes. Capacitors and Beads may also be used. Spark Gaps and Varistors. Beads and Resistors for low voltage.

46 Standards of Radiation Electric Field Global Standard: CISPR Japan: VCC class2 (Consumer Equipment) U.S.A.: FCC part15 Europe: EN55022 Other countries: Setting regulation based on CISPR Regulation of the frequency band is between 30MHz to 1000MHz for VCCI. Others are referred on the next page.

47 EMI Regulation Example for High Frequency Band (Tightening( Regulation for GHz band noise) 1. CISPR 11 Group 2 Class B (1999 industry, chemistry, medical) For equipment with embedded frequency of 400MHz and above Regulated frequency: 1-2.4GHz band Standard: 70dBuV/m and below (3m electric field intensity) 2. CISPR 22 CIS/G/210/CD (2001 IT equipment) For equipment with embedded frequency of 200MHz and above Regulated frequency: 1-2.7GHz band Standard: Average of 50dBuV/m and below, Max 70dBuV/m and below (3m electric field intensity) 3. FCC Part 15 (IT equipment) Measurement up to 2GHz is required for an operation between 108 to 500MHz band. Measurement up to 5GHz is required for an operation between 500 to 1000MHz band.

48 Mechanism of Radiation Noise 1 Digital waveform Spectrum Voltage (current) Measurement system: Oscilloscope Fourier transform Time axis is transformed to frequency. Measurement system: Spectrum Analyzer Noise (voltage, current) Noise standard restricts the noise received with an antenna. Time Frequency Digital wave is formed by various frequencies. Voltage (current) Spectrum Analyzer Oscilloscope Time Frequency

49 Mechanism of Radiation Noise 2 Flux occurs only with direct current. Current Flux Electric and magnetic fields occur with alternate current. Current Magnetic field Electric field Magnetic field Electric field voltage current Voltage Current 0V 0A 0V 0A Radiated from digital wave Vcc Noise Clock Noise Digital signal Vcc Leakage of high frequency IC IC

50 Mechanism of Radiation Noise 3 Magnetic field Electric field Magnetic field field Electric field Magnetic field Electric field Magnetic Electric field Antenna RF signal source Spectrum Analyzer Radiation electromagnetic field measurement (open site, anechoic chamber) Direct wave Antenna EUT Reflected wave Noise standard restricts the received noise value. Spectrum Analyzer

51 Mechanism of Radiation Noise 4 Ringing occurring Voltage Time Spectrum changes with waveform distortion. Voltage Time Level changes Noise Noise Frequency Cause: mismatching of transmission line Traveling wave Standing wave =traveling wave+reflected wave Reflected wave Frequency Because harmonics of a digital signal make a standing wave, the emission of the signal increases as noise. Transmission line pattern Mismatching of impedance

52 Fin.