Showing 2 results for Bijari
A. Bijari, S. H. Keshmiri , W. Wanburee,
Volume 8, Issue 1 (March 2012)
Abstract
This paper presents a nonlinear analytical model for micromechanical silicon ring resonators with bulk-mode vibrations. A distributed element model has been developed to describe the dynamic behavior of the micromechanical ring resonator. This model shows the nonlinear effects in a silicon ring resonator focusing on the effect of large amplitudes around the resonance frequency, material and electrical nonlinearities. Through the combination of geometrical and material nonlinearities, closed-form expressions for third-order nonlinearity in mechanical stiffness of bulk-mode ring resonators are obtained. Using the perturbation method and the method of harmonic balance, the expressions for describing the effect of nonlinearities on the resonance frequency and stability are derived. The results, which show the effect of varying the AC drive voltage, initial gap, DC applied voltage and the quality factor on the frequency response and resonant frequencies, are discussed in detail. The nonlinear model introduces an appropriate method in the field of bulk-mode ring resonator design for achieving sufficient power handling and low motional resistance.
A. Bijari, S. H. Keshmiri, W. Wanburee, Ch. Sriphung, R. Phatthanakun,
Volume 8, Issue 4 (December 2012)
Abstract
This paper presents the design and a new low-cost process for fabrication of a second-order micromechanical filter using UV-LIGA technology. The micromechanical filter consists of two identical bulk-mode ring resonators, mechanically coupled by a flexural-mode beam. A new lumped modeling approach is presented for the bulk-mode ring resonators and filter. The validity of the analytical derivation is investigated using the finite element method by ANSYS software. The new low-cost fabrication process is used to achieve a high aspect ratio of 16 with 3 μm gap spacing. The rigid graphite serves as a low-cost primary substrate and plating base of nickel as structural material. The fabrication process needs only three UV-lithography steps with Mylar masks to fabricate the main structure and pattern the printed circuit board as a secondary substrate. The frequency response of the fabricated filter is characterized as a function of the DC-bias voltage using a fully differential drive and sense interface circuit. The experimental results demonstrates micromechanical filter with center frequency in the vicinity of 10.31 MHz and percent bandwidth less than 0.3% using a DC-bias voltage of 60 V. The detailed fabrication process can be applied as an appropriate low-cost alternative to X-ray LIGA and silicon-based micromechanical filters.
