A Highly Temperature-Stable MAGFET Array for CMOS Smart Rotary Encoders

摘要

Temperature stability is one of the major concerns of sensors for practical applications. This paper presents a method for improving the temperature stability of CMOS magnetic rotary encoders. The main factor of the offset drift is the piezo-resistive effect due to the stress induced by packaging. A connection of four MAGFET elements offers a good offset drift cancellation capability while keeping the sensitivity. Using the proposed method, the offset drift is reduced from 0.4 percent without the cancellation to 0.15 percent with cancellation under the temperature range of 5 deg C to 80 deg C.