Q-Boosting Of Composite CMOS-MEMS Resonators By AC Current Low-Temperature Annealing

In this work a CMOS-MEMS balanced drive and sense thermal-piezoresistive resonator’s (CMOS-MEMS TPR) quality factor (Q) is doubled by ac drive annealing at low temperature (< 250°C), which overcomes reliability failure associated with high-current density DC annealing in CMOS. The design exploits the routing flexibility in CMOS to optimize the placement of high-loss metals for efficient transduction and reduced annealing current. The system can be easily implemented as a part of existing oscillator circuits without an additional cost in standard CMOS. Commercial components were used to realize an oscillator and characterize its phase noise (-107 dBc/Hz at 1 kHz offset) and Allan Deviation (75 ppm).