Very low complexity RF-MEMS technology for wide range tunable microwave filters

This paper presents tunable microstrip filters in the GHz range, fabricated on silicon in a very low complexity RF-MEMS process with only one metallization layer. Affected by a mechanic stress gradient in the metallization, free standing parts of the structure roll up. These bended beams can be switched onto the substrate by electrostatic actuation and thus tune the resonance frequency by changing the ε^{r eff} of the resonant structure. The technology offers the possibility to realize tunable filters with a small insertion loss of less than 1.5dB at 30GHz for bandpass and for bandstop filters and a large frequency shift of about 20% in operation frequency.