CMOS Micromechanical Bandpass Filter Design Using a Hierarchical MEMS Circuit Library

A 550 kHz CMOS micromechanical bandpass filter, is designed using a parameterized cell library, "NODAS," for schematic representation and behavioral HDL simulation. The filter employs a unique resonator and coupling spring structure implemented in a CMOS-MEMS technology. As an alternative design method, an equivalent SPICE model is derived for the filter. Frequency response around the filter passband from SPICE simulation matches that from NODAS simulation to within 2%. Compared to an equivalent SPICE model methodology, the NODAS methodology enables convenient composition and simulation of complicated MEMS. The experimental result of the fabricated device shows that the center frequency and bandwidth match NODAS simulation to within 3%, which provides component level validation of the NODAS-based MEMS design methodology. Nonideal effects such as manufacturing variations are also simulated and discussed.