Design, fabrication, and analysis of a spin-valve based current sensor

In this work, we suggest a novel current sensor design, based on spin valve technology, with a full Wheatstone bridge configuration. The principal characteristic is that the four magnetoresistance sensing elements, fully active, are deposited and patterned at the same time. This way, differences among them should be insignificant, so improving voltage offset and drift temperature parameters. The complete IC fabrication process involves only three lithography steps, making the process cheaper and faster. In order to get a balanced bridge, the measured current must be properly driven, by means of an auxiliary PCB. Some prototypes, with different input impedances, have been fabricated and characterized in the range of (0, 5A) and (0, 20 kHz), in different regimes. Linearity, sensitivity and offset voltage measurements, as well as temperature drift and sensitivity to external magnetic fields studies have been performed. The summary of the results have proved the sensors to be suitable for industrial applications, such as power electronic systems. (C) 2004 Elsevier B.V. All rights reserved.