Towards Zero Apparent Damping of MEMS Resonators by Force Feedback

A. Abrol, Z. Zhu, Y. Han, J.V. Clark
Auburn University,
United States

Keywords: artificial vacuum, performance on demand, podmems, high q, force feedback

Summary:

In this paper we study near-zero apparent damping of a MEMS resonator modeled in an ambient environment, where the energy lost per cycle is fed back into the system through a feedback force that is proportional to, and in the direction of, the velocity of proof mass. The MEMS (modeled as an equivalent circuit) and feedback electronics simulated as a system to properly model electrical latency, which affects the stability of the system. The benefits of mimicking the effects of low damping is to gain the sensitivity benefits of high quality factors (Q). High Q is beneficial for gyrometers, filters, clocks, etc. Traditional methods to reduce the effects of damping include reducing packaging pressure, acoustic anchor radiation, and thermoelastic damping, where quality factors from 1k to 1M have been observed. There has been an exponential increase in MEMS device cost associated with an increase in its quality factor. Since the method presented here is an active method, it will require additional power to operate; however, this tradeoff may be balanced by its ability to achieve a much higher range of Q without a significant increase in cost.