A precise two-dimensional MOS magnetic sensor is suggested and its performance is investigated. The dependence of sensor sensitivity on the device geometric parameters and on the biasing conditions is accurately determined by a twodimensional physical simulator which self-consistently solves the magnetic field equations and the carrier transport equations. From the simulation results, a modified equivalent circuit model for MOS magnetic sensor is proposed and included in SPICE model to fully analyze the operation of suggested magnetic field sensor. © 2009 SPIE.