A High Precision Digitally-Controlled Current Source for Magnetic-Field Measurements in Space

For spaceborne sensors power-efficient and lightweight circuitry is required, therefore, integrated solutions are preferred. In this paper an integrated current source is presented that can be used in the front-end of a fluxgate-magnetometer. A "radiation aware" design paradigm was followed to account for parameter shifts due to ionizing radiation and allow for radiation hardening without changing the topology.The digital current source achieves a dynamic range of more than 19 bits. It is based on a Delta-Sigma modulator with a digital pulse-width modulator as a quantizer. The digital-to-analog conversion is performed using a current-steering cell that employs chopping to minimize flicker noise. A fully-differential amplifier is used to drive an improved Howland current source.