Oscillation Circuit Evaluation Methods
What is "Drive Level" (2) <Measurement Method>
As described in the previous (Drive Level (1) ), the Drive Level is expressed by the following equation, and the target of the measurements is RL and i.
DL : Drive Level
RL: Load resonance resistance of crystal unit
i : Current value flowing through crystal unit (effective value)
１．Measurement method of the "RL: Load resonance resistance of crystal unit"
Using the network analyzer and the load-capacitance CL jigs, measure the RL of the experimental crystal unit according to the following procedure (when the NDK crystal unit is mounted on the board *1).
(*1) If the NDK crystal unit is not mounted on the board, prepare an appropriate NDK crystal unit separately and use it as the experimental crystal unit.
|Remove the crystal unit mounted on the board with a soldering iron.
|After the excess solder attached to the crystal unit is removed, waits until the crystal unit reaches a normal room temperature.
|Set crystal unit to the load capacitance CL jig (the capacitance of the load capacitance CL jig is the load capacitance CL specified in the specifications).
|Set the load capacitance CL jig in the network analyzer, and measure the RL of the crystal unit according to the manual of the network analyzer.
２．Measurement method of the " I : Current value flowing through the crystal unit (effective value)"
Set the experimental crystal unit to the board, measure the current value of the peak to peak at the specified temperature condition, and convert it to the effective value according to the following measurement procedure.
|Attach a lead wire to the experimental crystal unit and set it in on the board with the current probes passed through the lead wire.
|After the crystal unit and its surroundings are stabilized at the specified temperatures, crystal unit is oscillated and the peak to peak current is measured by an oscilloscope.
|The current value of the peak to peak is converted to an effective value. For the conversion, an effective value calculation method of a sinusoidal alternating current (see below) is used.
Irms: Current value flowing through crystal unit (effective value)
Ip-p: Current value flowing through crystal unit (peak to peak value)
The measurement image of the drive level is shown below.