17
Overview
2.2
Measurement Function
2.2.1
Measurement Parameters
Measurement parameters
：
Cs-Rs, Cs-D, Cp-Rp, Cp-D, Lp-Rp, Lp-Q, Ls-Rs, Ls-Q, G-B, R-X, Z-
θ
r,
Z-
θ
d
和
DCR
。
Among them
：
L: Inductance C: Capacitance
R: Resistance Z: Impedance X: Reactance
B: Density
G: Conductance
D: Loss
θ
: Phase angle
Q: Quality factor
DCR
：
DC resistance
The subscript s indicates serial equivalent, p indicates parallel equivalent
2.2.2
Equivalent Method
Series, Parallel.
The actual capacitance, inductance, and resistance are not ideal for pure reactance and purely
resistive components. They usually have both resistance and reactance components. An
actual impedance component can be modeled in series or parallel by an ideal resistor and an
ideal reactor (inductor or capacitor).
It can be mathematically converted using a formula, but the two forms are different,
inconsistency depends on the quality factor Q (or loss D).
Table 2-1
Series-parallel equivalent circuit
Circuit Form
Loss D
Equivalent Conversion
L
Lp
Rp
D=2
π
FLp/Rp=1/Q
Ls=Lp/(1+D
2
)
Rs=RpD
2
/(1+D
2
)
D=Rs/2
π
FLs=1/Q
Lp=(1+D
2
)Ls
Rp=(1+D
2
)Rs/D
2
C
Cp
Rp
D=1/2
π
FCpRp=1/Q
Cs=(1+D
2
)Cp
Rs=RpD
2
/(1+D
2
)
Cs
Rs
D=2
π
FCsRs=1/Q
Cp=Cs/(1+D
2
)
Rp=Rs(1+D
2
)/D
2
Definition for Q
、
D
、
Xs is
：
Q=Xs/Rs
，
D=Rs/Xs
，
Xs=1/2
π
FCs=2
π
FLs
Suggestion
Generally, a series equivalent circuit is used for components having a low impedance
value Z (for example, a high value capacitor and a low value inductor); a parallel
equivalent circuit is used for a component having a large impedance value Z (low value
capacitor and high value inductor).
At the same time, equivalent circuit must be determined according to the actual use of
component, such as capacitors, series equivalent circuit is used for power supply filtering,