Reliable, Compact, and Tunable MEMS Bandpass Filter Using Arrays of Series and Shunt Bridges for 28-GHz 5G Applications

Abstract

This work presents radio frequency (RF) microelectromechanical system (MEMS)-based compact, high power, and reliable tunable bandpass filter for millimeter-wave RF front end. The design is fabricated on 635- $\mu \text{m}$ alumina substrate using surface micromachining process. All functional building blocks of the filter are fabricated and tested independently to ensure the optimum filter performances. Total area of the filter is only 2.3 mm2 including bias lines and pads. The proposed filter can be tuned to any frequency between 27 and 29 GHz and it demonstrates insertion loss of 1.92 dB and matching of 23.4 dB at 28 GHz with fractional bandwidth (FBW) of 6.7%. Filter also gives bandwidth tuning of 4.4 GHz with acceptable loss. Filter works satisfactorily up to 1 billion cycles with 1 W of power. Device reliability tested within a low-cost package. To the best of our knowledge, this is the first reported tunable MEMS bandpass filter in the literature which has undergone and presented with extensive reliability results.