Design and simulation of a High-Q, Low Motional Resistance, Highly Linear IF Microelectromechanical Filter

In this paper, design and simulation of an IC-compatible microelectromechanical bandpass filter for use in intermediate frequency range of a wireless communication system is reported. This filter is composed of two high-Q microresonators coupled by a soft flexural-mode mechanical spring and can be implemented using either polysilicon surface micromachining technology or bulk micromachining of SOI wafers. The resonators with new design and structure determine the center frequency, while a mechanical coupling spring defines the bandwidth of the filter. Quarter-wavelength coupling is required on this microscale to alleviate mass-loading effects caused by similar resonator and coupler dimensions. Filter center frequencies around 71 MHz, 285 kHz bandwidth, quality factor of 250, associated insertion loss less than 0.44 dB, spurious-free dynamic ranges around 92 dB and input and output termination resistances on the order of 9 kOmega were obtained by this design.