Analysis of the impact of the processing time-delay on the stability of a digital GMI magnetometer

This paper discusses the impact of the time delay, due to the digital processing, on the stability of the closed-loop of a digital GMI magnetometer. In such a magnetometer, almost all the main functions involved in the electronic conditioning are realized digitally. These include an analog-to-digital conversion and a digital amplitude demodulation based on a Digital Down Conversion (DDC). The transfer function of each stage of the sensor is modeled in order to discuss the stability of the magnetometer according to the time delay of the digital processing. Results showed that with a careful adjustment of a set of parameters associated with the digital demodulation, the stability of closed-loop of the digital magnetometer could be theoretically obtained. The modeling results open doors to the experimentation of such magnetometer for a palette of potential applications.