Magnetic field analysis for the optimization of a GMR isolator for data transmission in power applications

A finite element magnetic field analysis of an isolator that exploits giant magnetoresistances, GMRs, as sensing elements is presented. The isolator basically consists of a coil, which generates a magnetic field (MF) when driven by a bias current, and at least two GMR elements, which vary their resistance depending on the MF intensity. This kind of isolator can be used to realize a structure that can be monolithically integrated by means of a suitable IC manufacturing process, thus allowing data transmission from high voltage parts to the low voltage front-end on the same chip. In this work the structure is analyzed as a function of different design parameters with the goal of obtaining an optimized structure where silicon area occupation and current consumption represent the two main constraints. The isolator geometry is first described, then the implemented finite element model is introduced. Simulation results obtained varying the number of coil turns, the excitation current intensity and the silicon area occupied are reported and discussed.