Abstract
This research focused on design and development of a fully differential CMOS-MEMS resonator oscillator system which spanned from concept to final system qualification. In this work, new flexural-mode ring resonator with a desired mode shape featuring an inherent differential mode of mechanical operation was designed using both analytical and finite element models. Two such resonators in low frequency and high frequency domains, centered at 1.39 MHz and 9.34 MHz, respectively were individually modeled using first principals, equations and simulation tools to evaluate and improve resonator performance. Devices were characterized over voltage, temperature, and pressure and device testing was used to validate designs and models, and to develop specifications for an oscillator system. Subsequently, both fully-differential CMOS-MEMS ring resonators integrated with their differential-type transimpedance amplifiers (TIA) have been demonstrated using a commercially available CMOS process. Low frequency resonator integrated with on-chip amplifier was chosen to be a candidate for final single chip oscillator realization due to its overall performance capabilities in terms of much higher transmission spectra (closer to 0dB), greater feed through suppression and exact phase shift (00) around resonance frequency to satisfy the oscillation criteria. Eventually, for the first time, fully differential CMOS-MEMS resonator oscillator has been implemented. In essence, this oscillator comprises a MEMS resonator and a high gain current to voltage amplifier hooked up in a positive feedback loop showing oscillation spectra at 1.39 MHz frequency.