A fast continuous-time demodulation circuit for a Hall sensor with stack capacitor offset cancellation technique

Abstract

A demodulation circuit for Hall sensor applications, which cancels offset by employing sequential voltage iterations across stack capacitors, is proposed in this paper. The circuit utilizes stack capacitors and a summing amplifier to perform offset sampling and cancellation. As there is no holding after sampling, the chopping ripple is effectively suppressed, thereby alleviating the use of area-consuming low pass filter (LPF). Under 0.18µm process, the Hall sensor with proposed stack capacitor offset cancellation (SCOC) demodulation circuit achieves higher bandwidth, better signal continuity, lower ripple and lower residual offset compared with two common offset cancellation (OC) circuits. The simulated ripple and residual offset are 38.1µT and 4.1µT respectively.