A simple and practical ac modulation method to reduce the hysteresis in tunneling magnetoresistive (TMR) sensor is demonstrated. It is shown that with a suitable ac modulation magnetic field that is applied along the sensing direction of the TMR sensor, the hysteresis in the sensor can be reduced to a negligible level. Also, depending on the amplitude of the modulation field, the sensitivity and the dynamic range of the TMR sensor can be tuned to meet practical requirements in specific applications. The influence of the modulation on the noise of TMR sensor is also studied.
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