Method and apparatus coupling together magneto field effect transistors in series to accumulate the effects of magnetic field for improved sensitivity and linearity

摘要

A circuit including daisy chain coupled triple drain magneto field effect transistors (MagFETs) for measuring magnetic field. The disclosed method and apparatus describe multiple MagFETs coupled together to accumulate voltage differentials generated in response to magnetic field. A lateral drain of a first triple drain MagFET is used to bias the gate of a second triple drain MagFET. The center drains and sources of each MagFET are biased with well matched current sources which permit the center drains and sources of each MagFET to float to a corresponding voltage biasing each triple drain MagFET near threshold. With the gate of each MagFET biased by a lateral drain of a prior MagFET, and with the source of each MagFET permitted to float to approximately a threshold voltage less than the corresponding gate voltage, the generated voltage differentials by each MagFET are accumulated thereby resulting in increased sensitivity to magnetic field. In addition, with the increased sensitivity, each MagFET is permitted to operate in a lower magnetic flux region resulting in improved overall linearity of differential voltage versus magnetic flux with the present invention.