Abstract: This paper presents of a design approach for a high sensitivity digital off diagonal Giant Magneto Impedance (GMI) sensor based FPGA integrated circuits. The proposed design includes a Direct Digital Synthetizer (DDS) and a Digital Down Converter (DDC) fully implemented in the FPGA and associated with the off- diagonal configuration. This magnetic configuration has the potential to improve the sensitivity by increasing the number of turns of the pick-up coil and to realize a sensor without using a difference amplifier that could be source of additional noise. An equivalent magnetic white noise level of 1.1 pT/ÖHz is measured. These results are achieved using a CoFeSiB micro wire of 2.5 cm length and 400 turns of coil wound around it. Results show that this white noise floor is mainly attributed to the Analog to Digital Converter (ADC).

Keywords: Giant Magneto Impedance (GMI), Off-diagonal configuration, Digital electronic conditioning.

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