Chopper stabilized CMOS integrated front-end for magnetic field measurement

This paper presents an analogue front-end dedicated to magnetic field measurement that is intended to be used in a mixed signal submicron CMOS microsystem. The front-end features a Hall device and its biasing circuitry both associated to a nested chopper-like structure. This system efficiently removes 1/f noise and reduces offset. The biasing amplifier is chopped at a frequency f_c in order to ensure steady ground referencing to the Hall device. This latter is operated using the spinning current technique at a frequency f_s = f_c/2. Sensitivities of 90 V/AT and resolutions of about 15 muT over a 1.6 kHz bandwidth extending from 5 to 1.6 kHz have been measured