A low phase-noise Pierce oscillator using a piezoelectric-on-silica micromechanical resonator

In this paper, we report on a low phase-noise 4.9 MHz oscillator using a fused silica micro-mechanical resonator. The resonator is implemented using a piezoelectric-on-silica structure, achieving high quality factor (Q ~15,860) and low motional impedance (R_m ~360 Ω). By interfacing the resonator to a CMOS amplifier, an oscillator phase noise of -138 dBc/Hz at 1 kHz, -154 dBc/Hz at 10 kHz, and -155 dBc/Hz at far-from-carrier offset frequencies has been achieved at a low-supply voltage. Vibration tests on the oscillator indicate an acceleration sensitivity of less than 4 ppb/g. The frequency tuning properties of the silica oscillator are also characterized for compensating frequency variations due to environmental effects.