Novel MEMS filters for on-chip transceiver architecture, modeling and experiments

Abstract

MEMS-based mechanical resonators and filters have shown promising characteristics in achieving high-Q values and good stability. In this paper, new designs for IC-compatible microelectromechanical intermediate frequency (IF) filters are introduced. These filters have been fabricated and tested and experimental results are included in this work. One of the novel filters is composed of two-cantilever beam resonators coupled by a soft flexural-mode beam. Different configurations of these filters and their RF simulation and experimental responses are presented. One of the advantages of these filters is that the coupling elements can be added from more than one side in order to have elliptical responses. We also introduce a novel V-shaped coupling element that is used to mechanically couple two clamped–clamped MEMS resonators laterally. The stiffness of the proposed V-shaped coupling element is adjustable via changing the length of the V sidelines and/or the V conjunction angle to flatten the filter passband. A two-pole bandpass filter operating in the IF range is constructed using these coupling elements. A lumped modeling approach is presented for fast and accurate filter design and optimization. Using finite-element (FE) analysis, the validity and accuracy of the lumped model are investigated. The fabricated filters have center frequencies varying from 700 kHz to 1.7 MHz, with quality factors of 300–1500 when tested at ambient pressure. The experimental results are presented and compared with lumped and finite-element simulation results.