Analysis, Design, and Optimization of the CHOPFET Magnetic Field Transducer

This paper presents the study of the chopperstabilized magnetic field effect transistor (CHOPFET), a high-resolution silicon magnetic transducer. After a full description of its structure and operating principle, a 3D multiphysics model is proposed. This model combines the electrical model of conventional silicon electronic devices (i.e., transistors) and the magnetic model in order to obtain accurate transduction effect prediction. Experimental results collected from a set of CHOPFET transducers fabricated in AMS 0.35 μm standard CMOS technology effortlessly match the simulations performed on the same process. Analysis and discussions reveal one key result: when the CHOPFET is appropriately biased, its channel current, IDS, can be lowered without magnetic sensitivity loss, i.e., the CHOPFET can achieve high-resolution performance even when operated in a low-power mode.