High stability quartz oscillators utilizing anharmonic mode LFE resonators

The main mode lateral field excited resonators exhibit high value of motional resistance and very low value of motional capacitance. One undesirable property of these resonators is difficult frequency calibration and oscillator frequency adjustment. The anharmonic mode resonators exhibit lower motional resistance and few times higher motional capacitance. Because of that frequency calibration and frequency adjustment in oscillator is significantly easier. Different versions of SC 301 and 310 mode resonators have been designed and elaborated over past several years. The results were optimized practically versions of 301 and 311 mode resonators. For lateral field excited resonators the double oven OCXO oscillator was designed. The resonators were mounted in oscillators. Next the short term stability, long term stability and thermal stability of oscillators were measured, using conventional methods of measurement. The long term frequency stability measurements were carried out in laboratory with ambient temperature stabilization in the range 20plusmn1degC. The oscillators exhibited long term frequency stability below 2 E-11 per day and short term frequency stability below 2 E-13 per second. The analysis of the oscillator parameters measurement showed main influence on them not resonator quality but the oscillator construction and utilized electronic components quality. The result of analysis of these parameters was the new design of hermetically sealed oscillator with carefully selected electronic component. The oscillators were hermetically sealed for prevent of environmental conditions