Authors: A.A. Seshia, W. Low, S.A. Bhave, R.T. Howe and S. Montague
Affilation: University of California, United States
Pages: 162 - 165
Keywords: micromechanical oscillator, resonator, resonant sensing, Pierce circuit
We present the design techniques and experimental characterization of a Pierce oscillator circuit adapted for micromechanical elements with resonant frequencies lying between 100 and 300 kHz. Micromechanical double-ended tuning fork resonators serve as the crystal element of the oscillator. The measured phase noise of these oscillators lies below -100 dBc/Hz at a frequency offset of 500 Hz away from the carrier with in-circuit quality factors exceeding 30000. This noise figure improves upon previous reported values and demonstrates the feasibility of a Pierce oscillator for micromechanical vibrating elements with resonant frequencies lying under 1 MHz. The value of the second harmonic distortion factor (HD2) is -44 dB for an output amplitude of 50 mV.