A Magnetic Feedback-Based Δ–Σ Digitizing Interface for Giant Magnetoresistance Sensors

Giant magnetoresistance sensors are popular for measurement of low magnetic fields due to their low-cost, easy-to-use, high-sensitivity design. However, the GMR sensors exhibit omnipolar, non-linear, and hysteretic voltage versus field characteristics, and operate over a limited range of input fields. In this brief, a simple digitizing interface, based on magnetic-feedback-based Delta-Sigma modulation, is proposed to overcome the aforementioned limitations of GMR sensors. The proposed interface operates the sensor at a quiescent magnetic field and renders a linear direct-digital output. The scheme is designed to measure bipolar fields. The methodology, analysis, and performance verification of the proposed interface are brought out in this brief. Experimental results of the developed interface show a non-linearity (N.L.) of just 0.52% over an enhanced measuring field range and significantly reduced hysteresis.