Sensitivity Recalibration of MEMS Microphones to Compensate Drift and Environmental Influences

Abstract In this paper a new method for sensitivity recalibration of capacitive MEMS microphones is presented. Recalibration can be applied to compensate ageing or environmental influences. Recalibration can be done by measuring the sensitivity for only one bias voltage after a stress test. A microphone with a variable bias voltage can measure its pull-in voltage. Unfortunately, the drift of the pull-in voltage does not correlate with the sensitivity drift. So a true self-calibration without a defined acoustical test signal was impossible.