A Noise Analysis Based Design Approach of a Fully Differential Voltage Controlled Current Source for Fluxgate Sensor Excitation

Fluxgate sensors can be used in a different range of applications, where the magnetic field needs to be measured. They are known for their high dynamic range and outstanding linearity. To drive the sensor a dedicated electronic circuitry is required to retain these excellent qualities. A fully differential voltage controlled current source can be used for the linearization of the fluxgate sensor via excitation of the feedback coil. In this paper a noise analysis was accomplished for an excitation circuit which is based on an Improved Howland Current Source in bridge configuration. Further, a noise improved design approach for a spaceborne fluxgate magnetometer is presented. For this reason a Verilog-A based model of a single ended operational amplifier is employed. Simulation results with Cadence Spectre ® show a signal-to-noise ratio of 119.9 dB, if the presented design flow is used.