A Fully-Differential CMOS-MEMS DETF Resonator Design with Extended Mass and Electrodes to Enable High Power Handling

We propose a novel differential drive and sense double-ended tuning fork (DETF) with wing electrodes to reduce the motional resistance ( $\boldsymbol{R_{m}}$ ) while achieving excellent power handling. The devices are fabricated using back end of line (BEOL) materials of $0.18\boldsymbol{\mu}\mathbf{m}$ 1P6M CMOS process. The wing electrodes are added to the high-velocity region to achieve high transduction efficiency. This increases the device mass ( $\boldsymbol{m_{r}}$ ) which requires increased stiffness ( $\boldsymbol{k_{r}}$ ) to maintain the same resonance frequency. The proposed design has resonance at 1 MHz in vacuum under a dc bias ( $\boldsymbol{V_{P}}$ ) of 30V with $\boldsymbol{R_{m}}$ of $250\ \mathbf{k}\boldsymbol{\Omega}$ for a $\boldsymbol{Q}$ of 2,300. The device can sustain the input power of 438 nW delivered to the resonator, corresponding to −5 dBm of the drive power from the network analyzer (NA), which is around 2000X higher as compared to traditional capacitive MEMS resonator design.