Phase Modulation Noise of a Magneto(Elasto) Electric Sensor Operating as a Magnetometer in the Non-Linear Regime–Theoretical and Experimental Studies

In this paper, we present the equivalent magnetic noise of a multi-push-pull Magneto(Elasto)Electric sensor implemented as a magnetometer, with a phase modulation circuitry. Here, in this paper, either a magnetic field or an electric field carrier was modulated by a low magnetic field signal at the sensor resonant frequency, offering an optimal sensitivity, and thereby, the lowest equivalent magnetic noise level at this working point. These two modes of excitation are respectively called E/E (Electric Excitation/Electric detection) and M/E (Magnetic excitation/Electric detection). Based on the constitutive equations and the Nyquist theorem, we have determined the expected sensitivities and the equivalent magnetic noise for the phase modulation. The experimental results were compared to the modeling and to a former amplitude modulation method in order to analyze the coherence of our results and assess this method against the classical AM mode, respectively. At present, the main noise source contributions by using phase modulation are attributed to the electronic circuitry.