Handling Notes
(4) Items calculated by equivalent constants and load capacitance
1
fs: Series resonance frequency
fp: Parallel resonance frequency
fs
fp
2 L1 C1
1
C0 C1
2 L
1 C0C1
C0
C1
: Capacitance ratio
C1
fL : Load resonance frequency
RL : Load resistance
fL fs
1
2 (C0CL)
2
C0
CL
RL R1 1
C1
2
1
CL : Load capacitance
Q : Quality factor
CL
C0
(fL/fs)1
2 fs L1
1
Q
R1
2 fs C1 R1
The equation fL shows that fL varies as load capacitance CL connected to the crystal unit changes and that fL becomes larger
as CL becomes smaller.
The equation RL shows the change in impedance with a load capacitance connected. The impedance of crystal unit becomes
larger as CL becomes smaller.
2. Oscillation circuit and crystal unit
(1) Equivalent circuit of oscillation circuit and oscillation conditions
A simplified equivalent circuit is shown below.
Crystal unit
Oscillation circuit
Crystal unit
Oscillation circuit
CL : Load capacitance
–
R
: Negative resistance
–
CL= XC
CL
XL
RL
XL : Reactance of crystal unit
–
X
C : Reactance of oscillation circuit
RL : Load resonance resistance
–
–
R
R
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KYOCERA AVX [ KYOCERA AVX ]
