CMOS integrated field coils for self-calibration of 3D hall-sensors

An integrated arrangement of field coils for on-chip self-calibration is presented. Routine tests for 3D Hall sensors are very complex and need special test hardware to generate a well-defined three-dimensional magnetic field. In combination with a high voltage current source, the integrated arrangement allows the generation of local magnetic fields up to 2 mT. In spite of process variations, the error of each coil's magnetic flux density is less than 1%. Magnetic tests can be done on-chip without need for additional external test equipment. Additionally, a low power mode allows for validity checks and online calibrations during measurements with a small magnetic flux density of 0.2 mT.