Tunable MEMS Capacitor for RF Applications

Radio Frequency MEMS devices have emerged to overcome the problem of high losses associated with semiconductors at high frequencies. A tunable MEMS capacitor is a micrometre-scale electronic device whose capacitance is controlled through different actuation mechanisms which govern the moving parts. It can have electrostatic or electrothermal actuators depending on the functional complexity and requires a predictable behavior over a continuous range of inputs. This work proposes an electrothermally actuated tunable MEMS capacitor suitable for filters, oscillators, phase shifters and impedance matching networks. The design utilizes bimetallic strip actuators instead of conventional asymmetric arm actuators. The model simulation using COMSOL Multiphysics has been able to provide surface deformation, temperature distribution, stress distribution and current density distribution results, and has indicated that the capacitance can be varied up to a tenth of its initial value.