Design and system-level simulation of a capacitive dual axis accelerometer

A system-level model of a bulk micromachined dual axis accelerometer is presented. The accelerometer has only one inertial mass, symmetrically suspended by four pairs of folded elastic beams. The size of the fabricated accelerometer is 5.4times5.4 mm². The displacement change of the inertial mass is converted to the change of differential capacitance between active combs and fixed combs. Generally, the input acceleration is mixed with the x-axis and the y-axis. In order to separate and pick off the mixed signal, the frequency-division method is adopted in the interface circuit. The paper details the Simulink model, which is used to evaluate the feasibility of the detective method. The simulation results validate the feasibility that the interface circuit can detect dual-axis acceleration separately and synchronously.