The lateral field excited anharmonic mode vibrating SC-cut resonators application in oscillators

The SC-cut anharmonic mode 301 and 310 resonators have been presented over past several years at the EFTF. Compared to main mode lateral field excited resonators, the anharmonic mode resonators exhibit a lower motional resistance and few times higher motional capacitance. For this reason, it is inherently easier to make frequency calibration and control of an anharmonic mode based oscillator. At the Tele and Radio Research Institute, lateral field excited resonators employing the main mode 300 and the anharmonic modes 301 and 311 were designed and manufactured. The same swept quartz material was used for all resonators, and the manufacture was based on the same technological process. The resonators were mounted in oscillators. Then the short term instability, the long term drift and the thermal frequency offset were measured, using conventional methods of measurement. Measurements of the long term frequency drift were carried out in the laboratory with constant ambient temperature 20±1°C. Moreover the long term frequency drift was corrected for atmospheric pressure and air humidity. As a result of the measurements, the short term instability of 7+10×10^-13/1s range and the long term drift of in 5+20×10^-11/day, after 1 month were achieved. The influence of the parameters of electronic components utilized in oscillators on oscillator parameters was observed. After changing the components that exhibited the highest instability the short and long term instability measurements were repeated. The measured long term drift was in the region of 1+6×10^-11/day. The parameters of anharmonic mode lateral field excited resonators are presented. The short term and long term instability and thermal frequency offset of oscillators utilizing lateral field anharmonic mode resonators are compared with those of oscillators utilizing classical lateral field excited SC cut resonators.