VHF enhancement of micromechanical resonator via structural modification

For the CMOS compatible micromechanical resonators in VHF transceiver applications, it is paramount to have a high quality factor (Q-factor) and high stiffness as it directly influences the dynamic range of the circuits. The resonator also needs to have a high natural frequency in order to reduce the effect of the external noise. A reduction in the size of the resonator may satisfy the above requirements. However, beyond a limit, this may increase its sensitivity to noise. In this paper, structural design improvements on an existing resonator have been carried out, and a prototype based on the new design has been fabricated and tested. The new design has demonstrated an improvement in both the natural frequency (typically 43%) and the Q-factor (typically 25%) as compared to the original design. The increase in natural frequency is due to the addition of reinforcements to the proof mass, and the improvement in Q-factor is due to a reduction in the squeeze film damping coefficient arising out of a higher driving frequency. (C) 2002 Elsevier Science B.V. All rights reserved.