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摘要
This paper reports the experimental results of parametric amplification applied to a harmonically forced resonant MEMS sensor. In this work parametric amplification of the forced response at resonance in the range 10-100 is investigated for an electrostatically actuated and sensed gyroscopic sensor. Several important factors pertinent to practical exploitation are highlighted. The main obstacle to high gain parametric amplification is the nonlinearity of the electrostatic force which becomes significant for high amplitude vibration. By significantly reducing the harmonic forcing level to just above the noise threshold, parametric amplification of the resonant response by a factor of 80 has been achieved whilst maintaining linear response characteristics. It is shown that parametric amplification modifies the shape of the Nyquist plot of the frequency response function from the conventional circle to that of a pronounced ellipse. This is shown to be due to generally unequal contributions to both the real and imaginary parts of the frequency response function and is related to the relative phase between the two harmonic excitations. Furthermore, the phase transition around resonance is shown to be slower for the parametrically amplified resonator. The relationship between the Q-factor and the bandwidth for the parametrically amplified resonator is investigated and is shown to be significantly different from that of a linear resonator with constant coefficients. A linearized theoretical model is used to confirm and understand these experimental findings. Further experimental tests have also been conducted to investigate the relationship between parametric gain and parametric excitation at the onset of nonlinear dynamic response.
- 出版日期2010-8
