Effects of the electrode positions on the dynamical behaviour of electrostatically actuated MEMS resonators

The influence of the lower electrode positions on the dynamic response of polysilicon MEMS resonators is studied and presented in this paper. The change in the frequency response of investigated MEMS resonators as function of the lower electrode positions is measured using a vibrometer analyzer. The decrease in the amplitude and velocity of oscillations if the lower electrode is moved from the beam free-end toward to the beam anchor is experimental monitored. The measurements are performed in ambient conditions in order to characterize the forced-response Q-factor of samples. A decrease of the Q- factor if the lower electrode is moved toward to the beam anchor is experimental determined. Different responses of MEMS resonators may be obtained if the position of the lower electrode is modified. Indeed the resonator stiffness, velocity and amplitude of oscillations are changed.