A magnetic field sensor for sensing an external magnetic field along a sensing direction comprises a sensor bridge. The sensor bridge has a first sensor leg that includes a first magnetoresistive sense element and a second sensor leg that includes a second magnetoresistive sense element. The first and second sense elements have respective a first and second pinned layers having corresponding first and second reference magnetizations. The second reference magnetization is oriented in an opposing direction relative to the first reference magnetization. The first and second sense elements have respective first and second sense layers, each having an indeterminate magnetization state. A permanent magnet layer is proximate the magnetoresistive sense elements. In the absence of an external magnetic field, the permanent magnet layer magnetically biases the indeterminate magnetization state of each sense layer in an in-plane orientation to produce a sense magnetization of the first and second sense layers.