Small giant magneto resistance/tunneling magnetoresistance（ GMR/TMR） sensor play an important role in high resolution measurements of weak magnetic signals. Aiming at problem that magnetic hysteresis problem occur in output response of small GMR/TMR sensor

so as to affect precision of detection

a hysteresis compensation method based on low noise current source controlled by digital signal processor（ DSP） is proposed.DSP platform is used to control a high stable current source to generate current

and the compensation magnetic field is generated by compensation coil which driven by the current

Therefore

the GMR/TMR sensors are always kept in a constant magnetic field and hysteresis suppression of the sens

ors is achieved. Meantime

low-noise current source is designed to reduce the additional noise caused by the the compensation system. Experimental results show that the RMSE of the built high precise current source is（ 3

5） × 10-6

and the hysteresis of GMR/TMR sensors is reduced by 90 % with compensation

and only 250 p T magnetic noise is generated from compensation system..