Self-calibration method for a sigma-delta micro-accelerometer

This paper presents a self-calibration method for a sigma-delta micro-accelerometer, based on the measurement of limit-cycles at the comparator´s output. Some information concerning the sensing cell´s parameters may be extracted from the shape of the limit-cycle, which depends on the characteristics of the micro-accelerometer (pulsation, damping, ...). By changing the coefficients of the discrete feedback filter, this information can then be made more accurate. This digital technique can be implemented with ease in the context of sigma-delta sensors. It is amplitude-independent and relatively insensitive to noise. Details concerning the implementation are discussed and some simulation results are given.