Bias-adaptive cross-coupled CMOS MAGFET pair for bipolar magnetic field detection

In the conventional cross-coupled CMOS magnetic field-effect transistor (MAGFET) pair, at least one MAGFET is self-biased. The output swing at the self-biased end is then inevitably limited to the threshold voltage of the self-biased MAGFET. This problem emerges for bipolar magnetic field sensing. In this paper, we propose a bias-adaptive voltage level shifter to remove the direct self-bias connection between the gate and the drain and to adjust the operating point at the output node, so as to achieve symmetric yet maximum positive and negative output swings. The improvements have been verified by HSPICE simulation.