Modeling and analysis of distributed MEMS phase shifter with metal-air-metal capacitor

In this paper, an equivalent- circuit model of MAM (metal-air-metal) capacitor applied in RF MEMS devices is proposed. Also, equivalent-circuit model of distributed MEMS phase shifter with MAM capacitor are presented. The parametric analysis of the proposed models and the designing method are also presented. By adopting the unit cell (0/11.25°) of 5-bit X-band distributed phase shifter, the paper discusses the model error and the efficiency of the proposed equivalent-circuit model. Compared with existing equivalent-circuit model, as for S₁₁, the model error of the proposed equivalent-circuit model could be less than 1 dB, decreased by about ten times, and the model error for phase shift per unit cell could be less than 0.5°, decreased by about thirteen times.