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The aim of this study is to quantify the energy loss mechanisms for single anchored double-ended tuning forks (DETF) — particularly, gas damping, thermoelastic dissipation (TED) and anchor damping. We performed ring-down measurements of quality factor (Q) as a function of pressure to confirm the absence of air damping. We also measured Q over a wide temperature range including where the coefficient...
We developed a model for the motional impedance Zm of electrostatic resonators that operate in a nonlinear regime. The model predicts that the Zm at resonance has the same expression as it has in the linear case. In addition, we developed a new measurement setup, which is based on a variable-phase feedback circuit. This setup enables the measurement of Zm at operating points that are unobservable...
In microelectromechanical systems resonators, nonlinear operation is feasible, but instabilities can arise if open-loop resonators operate above the critical vibration amplitude. This fact has led to a reluctance to operate resonator-based oscillators above this amplitude. This study experimentally demonstrates stable operation of these oscillators far beyond the critical vibration amplitude....
We present a biasing technique and a novel oscillator architecture for the elimination of frequency drifts in resonant electrostatic MEMS that are caused by the motion of charge present within dielectrics. We demonstrate more than two orders of magnitude improvement in stability for a test device operating as a frequency reference at 1.077 MHz, reducing frequency drift from more than 100 Hz over 3...
An ultra-sensitive, encapsulated, resonating strain gauge first presented in Transducers'09 was calibrated and used to study stress relaxation of sputtered 99.95% Platinum (Pt) thin films at temperatures of less than 100??C. Because of the extreme long-term stability of these encapsulated crystalline resonators and the ability to observe frequency changes at or below 1 ppm, this device offers a unique...
In this work, we develop a theoretical explanation for the temperature dependence of the nonlinear amplitude-frequency (A-f) effect in micromechanical resonators. Using this theory, we explain the discrepancy in frequency-temperature (f-T) characteristics between open-loop observation and closed-loop measurements. We show how the temperature dependence of the A-f effect introduces bias voltage dependence...
We present a hermetically encapsulated breathe-mode ring resonator with very high quality factor (~473,000) and frequency at 10.65 MHz and 13.29 MHz. The resonator's nonlinear behavior is experimentally characterized and theoretically analyzed for the first time. The maximum current handling is measured and verified using two different methods. We find that material nonlinearity (nonlinear Young's...
We develop an efficient characterization method for temperature compensated micromechanical resonators by employing empirical data analysis with an a priori model. We have previously demonstrated that electrostatic-tuning of a composite resonator with an accurate lookup table can achieve a temperature stability of ??3.2 ppm, but this characterization method was not suitable for commercialization since...
Encapsulated micromechanical resonator technology is becoming important as a potential replacement for quartz for several applications. In this work we report the nonlinear characterization, particularly the A-f effect, in these resonators. The A-f effect in quartz has been well studied in the 1970's and 1980's (Gagnepain, 1981) and (Gagnepain, 1987), as it dictates the maximum power (current) that...
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