A sensor assembly includes a first magneto-resistive field sensor in a first surface-mountable package, which measures first and second components of a magnetic field projected onto respective different first and second axes with respect to a spatial orientation of the sensor and to produce first position signals indicative of the measured first and second components. A second magneto-resistive field sensor in a second surface-mountable package measures at least a third component of the magnetic field projected onto at least a third axis with respect to the spatial orientation of the sensor, and to produce second position signals indicative of the measured third component. A substrate assembly orients the first field sensor in a first spatial orientation and to orient the second field sensor in a second spatial orientation so that the third axis is oriented out of a plane containing the first and second axes.