A new method of numerical analysis of MOS magnetic field sensors is described, which is based on a lumped discrete approach and the application of a general-purpose circuit-analysis program. The channel region of the device is represented by a network of identical L-type circuit cells. A cell consists exclusively of conventional MOS devices, independent voltage sources and controlled current sources, while the magnetic field appears as a parameter in some of these devices. The method allows for an accurate two-dimensional numerical analysis of MOS sensors, including effects which have been neglected hitherto, such as transverse current flow and nonuniform charge density across the channel. Numerical results are given for conventional MOS plates, split-drain MOS devices and distributed current source biased MOS Hall plates.