Design of a MEMS accelerometer using an integrated common gate differential MOSFET amplifier

The design, modeling, and feasibility of MEMS accelerometer based on common gate metal-oxide-semiconductor field effect transistors (MOSFETs) arranged in a differential readout configuration are presented. A traditional proof mass is suspended between two MOSFET channels and serves as a common gate electrode for both MOSFETs. This sensor design integrates transduction and amplification as acceleration induced displacement of the common gate proof mass modulates the relative gate capacitance and drain current of each transistor. The MOSFET pair, when integrated in a differential amplifier configuration generates a differential current flow. The differential electronic sensing scheme provides a good common mode rejection ratio (CMRR) and a symmetric single-axis measurement around 0 g with zero voltage offset. The model predicts sensitivities in the range of 1-15 mV/g over a 0-50 g operational range, which are comparable to other MEMS accelerometers, but offer a reduction in chip area and circuit complexity.