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Impedance of Passive Components SAMSUNG Impedance of Passive Components  Ideal Electrical Elements (Capacitance &Inductance)  Real Passive Components (Capacitor & Inductor) SAMSUNG Impedane, Introduction [Qualitative View] Response of Capacitor & Inductor DC - Capacitor: Conductive line is disconnected by capacitor. The only small DC current can pass, which is determined by resistance of dielectric. e.g.) C0G: IR=1011~12Ω / X5R: 108~9Ω DC - Inductor: All conductive line is connected through coil. DC current is determined by resistance of coil. e.g.) 1608m 0.47uH PI: Rdc(DCR)=43mΩ, 0402m 1nH High F: 400mΩ AC - Capacitor: AC current can pass easily through capacitor by electrostatic induction. AC - Inductor: AC current is blocked by inductor. *Electromagnetic induction SAMSUNG Impedane, Definition Impedance is a general term for resistance including reactance - Impedance: A measurement of difficulty for electric current to flow DC (freq.=0HZ): Z = R AC (freq. >0HZ): Z = R + jX SAMSUNG Reactance, induction [In-depth Study] C & L definition & induction of reactance formula C ≡ Q/V Q=CV, I=CdV/dt, I=C(jwV), Xc=V/I=1/jwC=1/j2πfC, Q: quantity of electric charge L ≡ Φ/I = dΦ/dI Φ=LI, dΦ/dt=LdI/dt, V=L(jwI), Xl=V/I=jwL=j2πfL, Φ: magnetic flux, Faraday's law of electromagnetic induction SAMSUNG Reactance, Xc, Capacitance Reactance of capacitance(|Xc|) decreases as frequencies increase - Also, |Xc| decreases as capacitance increases Xc=1/jwC=-j/2πfc → |Xc|=1/2πfc ※ In-depth study log(|Xc|)=log(1/2πfC)=-log(f)-log(2πC) if y=log(|Xc|) & x=log(f), y=-x-log(2πC) SAMSUNG Reactance, Xc, Capacitance [Qualitative View] Reason for decrease of Xc as freq. and C increase As frequency increase, Low frequency, Large Q, High V, High Z, High frequency, Small Q, Low V, Low Z As capacitance increase, Low Capacitance, Constant Q & Small C, High V, High Z, High Capacitance, Constant Q & Large C, Low V, Low Z SAMSUNG Reactance, XL, Inductance Reactance of inductance(|Xl|) increases as frequencies increase - Also, |XL| decreases as inductance decreases |XL| = 2πfL SAMSUNG Reactance, XL, Inductance [Qualitative View] Reason for decrease of XL as freq. and L increase As frequency increases - Electromagnetic induction is proportional to the chaning rate of magnetic flux. High F > High changing rate of current, > High changing rate of magnetic flux > High V > High Z As inductance increase - Increase of coil turn leads to high induced voltage. Large N > High L (inductance) > High electromagnetic induction > High V > High Z SAMSUNG Sum of Impedance (1) Total impedances in series and parallel are as below Total Impedance in Series - Z > Ztotal = Z1+Z2 Total Impedance in Series - Xc > 1/Ctotal=1/C1+1/C2 Total Impedance in Series - Xl > Ltotal = L1+L2 Total Impedance in Parallel - Z > 1/Ztotal = 1/Z1+1/Z2 Total Impedance in Parallel - Xc > Ctotal = C1+C2 Total Impedance in Parallel - Xl > 1/Ltotal = 1/L1+1/L2 SAMSUNG Sum of Impedance (2) Total impedance of C or L in series and parallel are as below Total Impedance in Series - Xc > Ctotal = 1/(1/C1+1/C2) Total Impedance in Series - Xl > Ltotal = L1+L2 = 3.2nH Total Impedance in Parallel - Xc > Ctotal = C1+C2 = 3.2uF Total Impedance in Parallel - Xl > Ltotal = 1/(1/L1+1/L2) SAMSUNG Sum of Impedance (3) Total impedance of C and L in series and parallel are as below Total Impedance in Series - X > 1uF, 1nH Total Impedance in Parallel - X > 1uF, 1nH SAMSUNG Impedance of Passive Components  Ideal Electrical Elements (Capacitance &Inductance)  Real Passive Components (Capacitor & Inductor) SAMSUNG Impedance of Real Capacitor (1) Real capacitor has resistance and inductance as well as capacitance - Capacitor turns into inductor above SRF (Self-Resonant Frequency) Z=-j/2πfC + ESR + j2πf * ESL SAMSUNG Impedance of Real Capacitor (2) Real capacitor has large resistance of IR at low frequency near DC - Large ESR can appear with wide frequency range around SRF At very low frequency near DC / At high frequency SAMSUNG Impedance of Real Capacitor (3), Web Library Impedance graph of 0603 1uF MLCC can be found at SEMCO homepage - SEMCO homepage : http://www.samsungsem.com/kr/index.jsp [Structure of MLCC] Dielectric(BaTiO3), Internal electrode(Ni), External Electrode (Cu) SAMSUNG Real Capacitors in Parallel Capacitors in parallel can decrease total impedance - Total impedance can be controlled by applying various capacitors in parallel Same capacitors in parallel / Different capacitors in parallel SAMSUNG Low ESL Capacitor (1) Low ESL capacitor shows lower ESL above SRF than normal MLCC - Low ESL capacitor has low impedance at high frequency [ESL Comparison according to MLCC types] MLCC: Multilayer Ceramic Capacitor LICC: Low Inductance Ceramic Capacitor SLIC: Super Low Inductance Capacitor 3T Cap.: 3 Terminal Capacitor VLC: Vertically Laminated Capacitor [Impedance Comparison] Normal vs. Low ESL SAMSUNG Low ESL Capacitor (2) Mounting area can be saved by applying low ESL capacitor (4*MLCC) → (1*3T-Capacitor) > Space Saving 36% 4*0603 1uF MLCC / 1*1005 4.3uF 3T-Cap. SAMSUNG Impedance of Real Inductor (1) Real inductor has resistance and capacitance as well as inductor - Inductor turns into capacitor above SRF (Self-Resonant Frequency). Parasitic element, Z=R+(j2πfL)||(-j/2πfC) SAMSUNG Impedance of Real Inductor (2), Web Library Measured impedance comparison between 2016 4.7uH and 2012 0.47uH -CIGW201610GH4R7MLE(4.7uH) vs. CIGT201208EHR47MNE (0.47uH) CIGW201610GH4R7MLE (2016 1.0Tmax): L=4.7uH, Rdc~240mΩ, C=5.8pF CIGT201208EHR47MNE (2012 0.8Tmax): L=0.47uH, Rdc~35mΩ, C=3.6pF