Residual stress analysis in RF MEMS comb line band reject filter

Studies are presented here on a tunable RF MEMS Comb line filter to analyze the effect of residual stress on its electromechanical characteristics. Realization of such a filter has already been reported by the authors [1]. However, analysis presented therein neglects the effect of residual stress, which may result in a significant modification of the beam actuation voltage. The issue is addressed here. This paper presents the simulated results as well as theoretically calculated results of a comb line filter due to the presence of residual stress gradient in respect of actuation voltage and spring constant of fixed-fixed beam characteristics for gold films. Modal analysis of the fixed-fixed beam structures are carried out for different values of residual stress gradients. Modal analysis predicts that higher values of tensile residual stress gradient are not favourable for fixed-fixed beam filter action. Modal analysis of fixed-fixed beam is analyzed by mechanical simulation tool COVENTORWARE-2008®.