A novel MEMS tunable comb resonator with non-uniform varied finger lengths

We present the development of tunable comb resonators that use a triangular comb of non-uniform varied finger lengths to the frequency tuning of the micromechanical resonator. The frequency tuning comb structure, composed of a triangular comb of non-uniform varied finger lengths, generates a linear electrostatic tuning force from the translational motion of the DC-biased comb. Increasing the tuning range of resonant frequency with less displacement, one of the challenges is there. Also, the nested folded beam suspension is used to reduce mechanical spring and thus reduce voltage. The electrostatic tuning force, the modified spring, and the resonant frequency were analyzed and investigated. The tunable comb resonator consists of three parts: the driving, sensing, and tuning parts. The resonant frequency of the resonator can be changed upon applying a DC voltage to the tuning part. To validate the theoretical analysis, this structure is simulated by Intellisuite software. Simulation results illustrate that the resonator has a resonant frequency of about 3578 Hz and a driving voltage of 5 V; the resonant frequency reaches 1549 Hz when a tuning voltage of 78 V is applied. The resonator has a maximum frequency tuning range of 57%, compared with previous works, the resonant frequency tuning range has been increased. However, the area of this resonator is about $1120\times 530 \mu ^{2}$ .