Frequency and bandwidth control of switchable microstrip bandpass filters using RF-MEMS ohmic switches

Abstract

In this paper a reconfigurable bandpass filter is designed using ohmic-contact cantilever-type Micro Electro Mechanical Systems (MEMS) switches., Tthe filter can switch between two different states with a center frequency tunable range of 13 % in C band. The topology allows achieving two accurate center frequencies, each associated with a precisely defined bandwidth, using six MEMS ohmic-switches. The design carefully takes into account the external quality factor for both filter states to ensure a good impedance match at each frequency. Coupling coefficients and resonator lengths produce the bandwidths and center frequencies required by design specifications. The filter is designed to have center frequencies of 5.5 and 6.2 GHz, with a fractional bandwidth (FBW) of 5 and 3 %, respectively. Filter specifications were successfully met with the proposed topology. The filter was fabricated on a quartz substrate and measured responses are in good agreement with simulations