Abstract: A magnetic field sensing device for simultaneously measuring all components of a magnetic field is disclosed. The present invention includes a conductive stack formed in a semiconductor substrate, where the conductive stack includes some ion-implanted layers abutting to each other, and each of the ion-implanted layers has a different and decreasing dosage level down to the bottom layer. The present invention also includes a first conductive contact on a first end of the top layer surface of the ion-implanted layers, and a second conductive contact on a second end of the top layer surface of the ion-implanted layers. A current flows into the first conductive contact and leave the second conductive contact, so that a horizontal magnetic field that exerts on the magnetic field sensing device is measured.