The effect of power-drive level on the calibration of the bridge instrument for the measurement of the quartz stability

In this paper, it is shown that the amplitude-frequency effect, a well known phenomenon in quartz crystal resonator, questions the short-term stability results of quartz crystal resonators computed from phase noise measurement in passive interferometer systems. This equipment allows one to measure the inherent phase stability of quartz crystal resonators in a passive circuit without the noise usually associated with an active oscillator. The short-term stability of the resonator given by the Allan standard deviation is usually computed with the Leeson frequency. A new method to characterize the short-term stability of crystal resonators by a phase bridge system is given.