Improving Temperature-Stability of CMOS Rotary Encoders Using a Parallel-Connected MAGFET Array

Abstract

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 % without the cancellation to 0.15 % with cancellation under the temperature range of 5°C to 80°C.