Low power damping control of a resonant sensor using back action in silicon nanowires

Abstract

This paper reports the damping control of a MEMS resonator, vibrating at several kilohertz, using tiny p-doped piezoresistive silicon nanowires (SiNW). Due to thermal piezoresistive back action (TPBA), DC-current biasing of the nanobeams induces a strong increase of the damping rate, about 2 decades above the intrinsic damping rate of the resonator. Intrinsic quality factor (QF) around 3.104 is here reduced to 450 thanks to an outstanding efficient TPBA. It is worth noting that QF can be here finely controlled for DC-current as low as a few tens μA, which leads to very low power consumption at constant voltage generator circuitry. This property is highly suitable for numerous applications, such as amplitude modulated resonant sensors (gyrometers, accelerometers...) or high performance resonant sensors, for which an accurate and repeatable control of the QF is required. Furthermore, the proposed mechanism allows bandwidth tuning and temperature compensation of the QF, without inducing parasitic crosstalk signals.