Wideband RF MEMS Impedance Tuners
Vähä-Heikkilä, T¹; Rantakari, P¹; Varis, J¹; Närhi, T^2
1MilliLab-VTT; ²ESA, ESTEC

New types of integrated impedance tuning circuits have been designed, realized and characterized both for microwave and millimeter wave frequencies. The circuits were designed to be used as impedance tuners in on-wafer noise parameter measurements to tune the input impedance of a device under test. Currently, either manual or motorized waveguide impedance tuners are used in noise parameter measurements above 50 GHz [1,2]. The circuits developed in this work are based on MicroElectroMechanical Systems (MEMS) technology. The circuits are loaded line structures, where switched MEMS capacitors are used as tuning elements. In general, well designed distributed loaded line circuits have good wideband matching and low loss. Circuits realized in this work have typically 6 to 10 switched MEMS capacitors producing 2^6…2^10 = 64…1024 different impedances. Full-length paper presents the design of the circuits as well as measured performance up to 110 GHz.