Abstract:
The dissertation presents the design of an electrothermally actuated in plane bidirectionally
translatable and symmetric RF-MEMS varactor with a maximum achievable tuneability of 1100%.
The varactor is mounted on a coplanar waveguide (CPW) transmission line. Compliant mechanical
amplifiers (CMA) have been utilized to amplify the output of chevron actuators and provide
greater displacements and contact forces. The main emphasis of this work is to propose the design
a novel varactor having a wide and linear tuning range, with the capacitive part of the device
independent of the actuation part, with the device exhibiting a high capacitance ratio and quality
factor. The device is designed according to the constraints of the standardized and cost effective
SOI-MUMPs fabrication process, offered by MEMSCAP Inc, USA. The proposed device has an
actuation voltage of 1.3 V and a nominal capacitance of 0.70 pF. An insertion loss better than -10
dB and return loss better than -1 dB is observed at 2 GHz. The change of capacitance on the CPW
transmission line, allows us to change the phase velocity of the device, hence opening the door for
a phase shifter application. The device measures 4×4 mm. The finite element analysis (FEM) of
the device is conducted in COMSOL.
