A method includes generating an electrical signal representing a magnetic field using a magnetic field sensor having alternating layers of magneto-strictive material and piezo-electric material. The method also includes performing up-conversion or down-conversion so that the electrical signal representing the magnetic field has a higher or lower frequency than a frequency of the magnetic field. The up-conversion or down-conversion is performed before the magnetic field is converted into the electrical signal. The up-conversion or down-conversion could be performed by repeatedly sensitizing and desensitizing the magnetic field sensor. This could be done using a permanent magnet and an electromagnet, an electromagnet without a permanent magnet, or a movable permanent magnet. The up-conversion or down-conversion could also be performed by chopping the magnetic field. The chopping could involve intermittently shielding the magnetic field sensor from the magnetic field or moving the magnetic field sensor with respect to the magnetic field.