A simplified modeling approach for a MEMS capacitive sensor

Abstract

This paper reports two behavioral models for a MEMS capacitive sensor and presents their simulation results for a bootstrapped continuous-time pre-amplifier. The first model uses a simplistic voltage-source based approach to imitate the variable capacitance in the sensor, while the other accurately models the mechanical and electrostatic forces inside the sensor in VerilogA. It is demonstrated through simulation results that the simple model can be used for a large input range without considerable differences as compared to the accurate model, proving it viable for functional simulations. Whereas, the accurate model traces the performance of the pre-amplifier in the presence of mechanical and electrostatic limitations of the sensor, revealing differences in the results for those cases where the non-linear response of the sensor is not negligible.