A magnetic sensor apparatus includes a magnetic field generating circuit which is configured to generate a magnetic field, a magnetic field sensor circuit which is configured to output a sensor signal in response to the magnetic field, which sensor signal has a signal amplitude dependent on a sensitivity of the magnetic field sensor circuit, an amplifier circuit which is configured to amplify the sensor signal and to output an amplified sensor signal with an amplified signal amplitude, and a control circuit which is configured to use a setting signal to set a supply signal of the magnetic field sensor circuit and/or a gain of the amplifier circuit such that the amplified signal amplitude corresponds to a target amplitude.