Bulk silicon micromachined suspended fixed-end SiO₂ film capacitor for passive high-pass RC filter

We reported a suspended fixed-end 5 μm thin SiO₂ film beam and plate MEMS capacitor for passive high-pass RC filter. This suspended structure was fabricated using bulk silicon two-sided alignment micromachining technology. The dynamic model included both a first order derivative of a high-pass filter electrical system and MEMS variable capacitors driven by electrostatic force. The room temperature experiment showed that the MEMS high-pass filter circuit can convert a rectangular wave input signal into high frequency spikes at its output. Finite element calculating software COMSOL and numerical simulation MATLAB were both used to evaluate the motion modal and the output voltage. Compared with the commercial static capacitor in a high-pass filter, we could also find that the coupling of the electrostatic force and dynamic motion of the electrode plate in the designed single device and dual-device could show an asymmetric offset voltage electrical response.