An improved method for measuring the DLD characteristics of quartz resonators

This paper describes an improved technique for precise DLD measurement, based on the transistor Colpitts oscillator method that can change the resonator driving current from less than 0.1 mA to 1 mA. Using this technique we show that some quartz resonators have many frequency jumps depending on the resonator drive current. We also show the phase noise characteristics of oscillation frequency measured in the vicinity of the resonator current at which there is a current-dependent frequency jump. From the experimental results, it is shown that the phase noise level becomes high when the current is selected to cause a frequency jump, compared with when the current level is normal.