Sensitivity enhancement of MEMS inertial sensors using negative springs and active control

In this paper, we present a device in which the inherent control scheme of force-feedback loops in Sigma/Delta -architecture [1] is used for increasing the mechanical sensitivity of differential capacitive inertial transducers in combination with "negative springs". As a consequence, the input-referred electronic noise and quantization-noise is significantly reduced in the signal band. Since electronic noise can influence the stability of the feedback loop, EM-theory is tailored to micromechanical sense loops. This forms the basis for analyzing on the system performance and the system limitations. Results from system simulation and measurement of an accelerometer demonstrate a significant improvement in sensitivity. (C) 2002 Elsevier Science B.V. All rights reserved.