A fabrication process and apparatus provide a high-performance magnetic field sensor (200) from two differential sensor configurations (201, 211) which require only two distinct pinning axes (206, 216) which are formed from a single reference layer (60) that is etched into high aspect ratio shapes (62, 63) with their long axes drawn with different orientations so that, upon treating the reference layers with a properly aligned saturating field (90) and then removing the saturating field, the high aspect ratio patterns provide a shape anisotropy that forces the magnetization of each patterned shape (62, 63) to relax along its respective desired axis. Upon heating and cooling, the ferromagnetic film is pinned in the different desired directions.