A mechanistic approach to tuning of MEMS resonators

A novel method of bidirectional frequency tuning of a beam-type MEMS resonator is presented. This method is based on the use of follower and axial end loads that are shown to decrease and increase the resonant frequency of the beam. The end loads were implemented in the resonator through electrostatic forces that act near the free end of the beam through specially designed comb fingers. Preliminary experimental results on fabricated resonators confirm some of the theoretical results and illustrate the change in resonant frequency with varying end load. A control scheme that uses these end loads to time the resonant frequency of the resonator to any desired frequency is provided. For a particular design, we show that fast and effective double sided tuning, i.e. both increase and decrease of the natural frequency, can be achieved with a range of up to 20% of the original resonant frequency.