Symmetric toggle structured MEMS linear variable capacitor with large tunning ratio

A microelectromechanical-system (MEMS) variable capacitor with symmetric toggle structure is proposed to achieve an excellent linearity of the C-V response and a large capacitance tuning ratio. Based on lever principle, flexible top plate of the capacitor moves upwards when applying the voltage on the control electrodes increases, which results in a highly linear decrease of the capacitance with increasing control voltage. The proposed MEMS variable capacitor was modeled and simulated using ANSYS software and fabricated using surface micromachining process. The results show a high linearity factor (LF) of 96.3% in C-V response and a large tuning ratio of 160% in a low actuation voltage range from 0 V to 30 V. The LF even reaches 98.9% from 10 V to 30 V.