Comparative Analysis of Multiple Feedback and Sallen Key Band-Pass Filters for Development of Ferrite Based High Sensitive Fluxgate Sensor

Abstract

Geomagnetic storms and sub-storms, sudden commencement, and geomagnetic pulsations are a worldwide disturbance of earth's magnetic field which causes significant damage across the world with a single event. Fluxgate sensor is essential in order to predict such occurrence of the major disturbances. In this study, comparative analysis of Multiple Feedback Band-Pass Filter (MFB-BPF) and Sallen Key Band-Pass Filter (SK-BPF) for the implementation of ferrite based high sensitive Fluxgate Sensor (FS) for earth's magnetic field explorations was carried out using Multisim MATLAB. The harmonics responses of the sensing coil output voltage for the designed fluxgate sensor was tested using the designed second-order MFB-BPF and SK-BPF. The prototype single-axis fluxgate sensor was used to obtain 2nd harmonic magnetic field response with Helmholtz coil. Results show that the 2nd harmonics produced the highest amplitudes of 45.61mV at an excitation current of 18.75mA for MFB-BPF and 51.20mV at excitation current of 50.00mA for the SK-BPF respectively. An indication that the core was strongly saturated at the 2nd harmonics and the MFB-BPF performance proved its superiority over the SK-BPF. The MFB-BPF can be adapted for the development of a high sensitive fluxgate sensor which can be used for earth magnetic field exploration.