A Novel Dual Torsional MEMS Suspended Gate FET (DTM-SGFET) Accelerometer

Abstract-In this work, we report a CMOS-MEMS accelerometer with a dual torsional MEMS structure in which variation in air gap due to z-axis acceleration is transformed to variation in the output voltage using differential amplifier configuration of Suspended Gate Field Effect Transistors (SGFETs). It exploits the change in the effective gate capacitance of SGFET due to change in air gap and the dependence of body effect coefficient, threshold voltage and drain current of SGFET on the effective gate capacitance for transforming displacement to current. The circuit implements a differential amplifier configuration of the 4 SGFETs integrated with the dual torsional MEMS structure to get voltage output. The proposed accelerometer exhibits sensitivity of 69.52 $\mathrm{mV} / \mathrm{g}$, a maximum non-linearity of 7.07 % Full Scale (FS) for the dynamic range of $\pm 6 \mathrm{~g}$. The non-linearity reduces to 0.54 % FS for $\pm 2 g$.