In this paper, we examine the problems related to orthogonal fluxgates realized using magnetic microwires as core. Starting from a description of orthogonal fluxgates evolution, we give a theoretical analysis of the problems involving the full saturation of the wire, necessary condition to obtain proper working conditions. Bi-metallic wires (magnetic layer on copper wire, carrying the excitation current) have been proposed to achieve full saturation using lower current. In this paper, we present a further improvement: we realized microwires with insulation layer between the copper wire and the magnetic layer. The current flows only into the copper, regardless of the working frequency. Using insulation layer, we achieve 20 mA saturation current at 10 kHz, which is 3 times smaller than for similar wires without insulation layer.
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