A wide-range frequency tunable SMR-CMOS oscillator for gas sensing

Precise-frequency tunability over a wide-range plays an important role in the SMR (solidly mounted resonators) CMOS oscillator circuit. Although commercially available network analyzers have been the standard for highly sensitive mass sensing using SMR, it is not possible to miniaturize it for mobile sensor. In this work, the wide-range of resonance frequency is tuned by changing the number of inverter chains. The effect of inverter chains for the device sensitivity is also investigated. We also show capacitors used for starting a resonance play an important role in the device sensitivity. We believe this technique will be an essential platform for one-chip SMR-CMOS gas sensor having different resonance frequencies due to the selection of piezoelectric materials or the process variation during the fabrication.