Handling Notes
The oscillation start-up conditions are described as
RL R
and in order to oscillate the crystal unit accurately, it must be designed such that the negative resistance of the oscillation
circuit becomes bigger comparing with the resonance resistance value at the time of loading. This ratio is called oscillation
margin degree MOSC and it is one of critical factors when designing the oscillation circuit and is described as below.
For oscillation circuit designing conditions, it is recommended that an oscillation circuit be designed using a negative
resistance of a value five to ten times or more larger than RL calculated from the resonance resistance specification value.
M
OSC R / RL 5
In a steady oscillation state, the load resonance resistance is given as follows:
RL R
The mutual conductance of the oscillation circuit decreases after the oscillation has started to continuously compensate for
the power loss due to the load resonance resistance of the crystal unit, which continues oscillation.
The frequency condition is given as follows:
XL XC, XL XC 0
As shown in the following figure, the reactance of the crystal unit varies to a value matching the load capacitance of the
oscillation circuit CL XC. Thus an oscillation frequency is determined.
+
X
fp
fs
fL
fs : Series resonance frequency
fL : Load resonance frequency
fp : Parallel resonance frequency
Frequency
Le
–1/ CL
–
X
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KYOCERA AVX [ KYOCERA AVX ]
