MEMS variable capacitor with superior linearity and large tuning ratio by moving the plate to the increasing-gap direction

This paper reports an innovative and simple method to achieve highly linear capacitance vs. voltage response and large tuning ratio in a parallel-plate MEMS variable capacitor by moving the plate to the increasing-gap direction. The proposed structure adopted a levering actuator to achieve the opposite moving direction and large displacement of the top plate. The proposed MEMS variable capacitor, which was made by metal surface micromachining, showed excellent linearity factor of 99.1% in C-V response and the capacitance tuning ratio of 178% were achieved at 2GHz.