Thermally-actuated and piezoresistively-sensed CMOS-MEMS resonator array using differential-mode operation

A very-high-frequency (VHF) bulk-mode II-BAR CMOS-MEMS resonator array with electrothermal actuation and piezoresistive sensing (thermal-piezoresistive transduction) under a novel differential mode of operation has been demonstrated for the first time using a standard 0.35μm CMOS process. The proposed array consists of SiO₂ and embedded polysilicon, the former of which provides high-Q structural material while the latter serves as both joule-heating elements and piezoresistors. Such a thermal-piezoresistive II-BAR array technique not only inherits all advantages from the single II-BAR but also shows great potential for low feedthrough, low motional impedance, and high power efficiency in VHF or ultra-high-frequency (UHF) operation using advanced down scaling and large-scale integrated (LSI) arrays.