Electrically coupled MEMS bandpass filters

This paper, the first of the two parts, presents coupling techniques for implementation of high order narrow-bandwidth bandpass filters from micromechanical resonators using electrical coupling elements. Active and passive coupling elements are used in this work to implement high order resonant systems from individual MEMS resonators. The concept of passive coupling of resonators using capacitors as the coupling elements for filter synthesis and its electromechanical modeling is presented. Active coupling of resonators using transistor-based amplifying circuits is introduced and demonstrated as well. Capacitively coupled bandpass filters with integrated coupling capacitors and filter quality factor as high as 1500 at operating frequency of 810 kHz are practically demonstrated. 2× Q-amplification was obtained from a resonator array consisting of three resonator stages interconnected with active interface circuits.