Specifications
1.5 Component dependency factors
The measured impedance value of a component depends on several measurement conditions, such
as test frequency, and test signal level. Effects of these component dependency factors are different
for different types of materials used in the component, and by the manufacturing process used. The
following are typical dependency factors that affect the impedance values of measured components.
1.5.1 Frequency
Frequency dependency is common to all real-world components because of the existence of para-
sitics. Not all parasitics affect the measurement, but some prominent parasitics determine the com-
ponent’s frequency characteristics. The prominent parasitics will be different when the impedance
value of the primary element is not the same. Figures 1-7 through 1-9 show the typical frequency
response for real-world capacitors, inductors, and resistors.
Figure 1-7. Capacitor frequency response
Figure 1-8. Inductor frequency response
Cp
L
Rs
Rs
w
L
|Z |
q
q
0
º
SRF
1
wCp
Log f
Log |
Z
|
Cp
L
Rs
Rp
Rs
w
L
|Z
|
SRF
1
wCp
Rp
L
og
f
Log |Z|
Cp: Stray capacitance
Rs: Resistance of winding
Rp: Parallel resistance
equivalent to core loss
(b) Inductor with high core loss(a) General inductor
Frequency
Frequency
q
–90º
90º
q
0
º
–90º
90º
C
Ls
Rs
R
s
Ls
0º 0º
–90º
90º
SRF
Frequency
1
C
Log f
Log |Z|
|Z|
R
s
Ls
|Z|
SRF
Frequency
1
C
Log f
Log |Z
|
Ls: Lead inductance
Rs: Equivalent series resistance (ESR)
(b) Capacitor with large ESR(a) General capacitor
q
–90º
90º
q
1-5