Oscillation Circuit Evaluation Methods
What is "Negative Resistance" (2) <Measurement Method>
First, remove the crystal unit mounted on your circuit board and connect the resistor in series with the crystal unit. Next, set the resistance of the resistor to a sufficiently small value and turn on the circuit.
And then, check the state of oscillation with the spectrum analyzer. As the resistance of the resistor increases, the spectrum peak signal disappears at a certain point.
Then, as the resistance value is lowered, a peak signal will be generated again.
The value obtained by adding the resistance value of the crystal unit to the resistance value at the time when the peak signal is generated again is used as the negative resistance value in the circuit (*1).
The method described above is a standard method, and depending on the circuit conditions, measurements may be made according to procedures and methods different from those described above.
※1 Negative resistance = Resistance of a resistor + Resistance of a crystal unit
【FIG】A resistor is connected to the circuit board borrowed from the customer, and oscillation is confirmed by a spectrum analyzer.