BM28723AMUV
2 The Value of the LC Filter Circuit Computed Equation - continued
The transfer function H(s) of the LC filter circuit of Figure 75. becomes the following.
1
LC
ω2
g
H
s
1
1
LC
ω
s 2
s
s 2
s
ω2
Cg
R
g
Q
The ω and Q become the followings here.
1
LC
1
ω2
ω
2πfCL
fCL
g
2π LC
g
C
L
g
1
2
C
L
g
Q
R
RL
Therefore, L and Cg become the followings.
1
ω2C
RL
4πfCLQ
Q
Q
L
Cg
g
ωR πfCLRL
The RL and L should be made known, and fCL is set up, and Cg is decided.
3 The Settlement of the Inductance Value of the Coil
A standard for selection of the L value of a coil to use is to take the following consideration except for the factor such as a low
cost, miniaturization and thin.
1.When the inductance value was made small
•Circuit electric currents increase without a signal. Efficiency in the low output power gets bad.
•Direct current resistance value of the coil becomes small.
Therefore, maximum output power becomes bigger.
Rated DC current and Temperature rise current of the coil become high.
2.When the inductance value was made large
•Circuit electric current is decrease without a signal. Efficiency in the low output power improves.
•Direct current resistance value of the coil becomes big.
Therefore, maximum output power becomes smaller.
Rated DC current and Temperature rise current of the coil becomes low.
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TSZ22111 • 15 • 001
31.Aug.2018 Rev.001