STRESSED SAW MONO OR DUAL OSCILLATOR STABILITY

Frequency stability of oscillators implemented with SAW delay lines on statically stressed quartz substrates has been investigated for applications to sensors. These oscillators under changes of surrounding hydrostatic pressure or temperature behave quite differently from unstressed oscillators. A high sensitivity to environmental pressure variation was observed. It was measured as a function of the static stress magnitude and reaches a few I0-6/mbar. Moreover the change in temperature frequency shift versus stress for AT cut quartz substrates is reported. Then taking into account these phenomena, aging of dual stressed oscillators over a few hours, several days and months was found.