Ambient temperature and bias conditions induced frequency drifts in an uncompensated SOI piezoresistive resonator

• Published in: Sensors and actuators. A. Physical. 2013-11, Vol.202, p.140-146
• Main Authors: Tu, C., Lee, J.E.-Y.
• Format: Article
• Language: English
• Subjects: Ambient temperature; Bias; Detection; Devices; Dog-bone resonator; Frequency drift; Instability; Piezoresistive sensing; Resonant frequencies; Resonant frequency drift; Resonators
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2013.02.023

► Experimental results on frequency stability of a piezoresistive SOI resonator tracked over 15–25h. ► Fixing the current or voltage affects the frequency stability differently. ► Temperature change alone cannot account for frequency drift when bias voltage is fixed. Piezoresistive sensing has been demonstrated in literature to be more insensitive to geometric scaling and capable of affording substantially higher electromechanical conversion over capacitive sensing. Nonetheless, the bias current through the device required of this sensing method could lead to Joule heating effect and potentially introduce instabilities in the frequency. As such, the dependence of the resonance frequency on ambient temperature and bias conditions in such case becomes more complicated and needs to be examined. In this paper, we track the resonant frequency of such a piezoresistive resonator together with the ambient temperature over 15–25h. We have found that the frequency shifts can be correlated with changes in ambient temperature. Additional frequency drifts due to the bias current were not observable even when the bias current was as high as 5mA (corresponding to 4mW of power), which was enough to yield a resonant peak of 24dB above the capacitive feedthrough floor. Also, it was experimentally observed that the resonant frequency is dependent on the bias current or voltage.