Design of RF MEMS phase shifter based on saw-shaped CPW

Abstract

The operating principle of the RF MEMS phase shifter is described. Then the equivalent circuit of the MEMS phase shifter has been established and the capacitances of the MEMS bridges in both ldquouprdquo and ldquodownrdquo state are analyzed. Then the approach of using the saw-shaped CPW to decrease the return loss introduced by the insulation layer is proposed. By using network theory, the circuit simulation tool and CST microwave studio simulation tool, the proposed RF MEMS phase shifter is modeled. Simulation results show that the proposed model has the return loss less than -10 dB and the insertion loss more than -2 dB in 2 GRz bandwidth range. At the same time, for one RF MEMS switch-type bridge, as high as 22.5 degrees phase shift is realized.