Roozbeh Tabrizian

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We discuss the contribution of phonon interactions in determining the upper limit of f.Q product in micromechanical resonators. There is a perception in the MEMS community that the maximum f.Q product of a microresonator is limited to a “frequency-independent constant” determined by the material properties of the resonator [1]. In this paper, we discuss(More)
This paper introduces an active electrical technique for dynamic tuning of MEMS resonators. The proposed technique is based on using the resonator output current to generate displacement or acceleration signals by integration or differentiation operations, respectively. The resulting signal is then scaled to generate an appropriate tuning signal. When(More)
This paper reports on the design, simulation and characterization of small form factor, tunable piezoelectric MEMS resonators for real time clock applications (32.768 kHz). The structures were fabricated on a thin-film AlN-on-SOI substrate to enable piezoelectric actuation of an out-of-plane flexural mode, as well as electrostatic frequency tuning by(More)
This paper reports on a new implementation of integrated lumped filters with improved out-of-band rejection and passband loss. Inductive parasitics are exploited to provide additional transmission zeros at the high frequency end, which can improve both the out-of-band rejection and roll-off. Thick silver is electroplated to reduce the insertion loss and(More)
This paper reports on the design, fabrication, and characterization of a small form factor, piezoelectrically transduced, tunable micromechanical resonator for real-time clock (RTC) applications (32.768 kHz). The device was designed to resonate in an out-of-plane flexural mode to simultaneously achieve low-frequency operation and reduced motional resistance(More)
This paper reports on the design, implementation and characterization of a low phase-noise 27 MHz MEMS oscillator with sub-ppm temperature instability based on a high-Q composite bulk acoustic wave (BAW) resonator. An array of silicon dioxide (SiO2) pillars has been uniformly embedded in the body of a piezoelectrically transduced silicon resonator to(More)
Fundamental characteristics of MEMS resonators such as acoustic velocity and energy dissipation may have strong temperature and process dependencies that must be carefully compensated in applications requiring high degrees of stability and accuracy. This paper presents an overview of compensation, tuning, and trimming techniques for MEMS resonators. The use(More)
This paper presents tunable width-extensional mode bulk acoustic resonators that are piezoelectrically-actuated and sensed using thin layers of AlN on the sidewalls as well as the top surface. By using both longitudinal and transverse piezoelectric effects of conformally-sputtered AlN layers on sidewalls and top surface of a 20 m thick resonator, a low(More)