Piezoelectric oscillation quartz crystal plate - has specified width to length relation for increased attenuation of secondary waves

摘要

The piezoelectric oscillation crystal is a rod-shaped quartz crystal plate of DT-section. In order to attain the optimum secondary wave attenuation, its width-to-length relation is chosen in the range of 0.25 to 0.35, pref. 0.3. In this range the deep secondary resonance has a relatively great frequency spacing from the main wave. The higher frequency secondary resonances are strongly inter-coupled, thus being of high ohmic nature. In this manner they do not form interferences even if the oscillator is used in filters. The frequency dependence on temp. corresponds to a parabola. In this manner the attenuation of the secondary waves, partic. in filter applications is considerably increased.