Correlated double sampling for noise reduction in magnetoresistive sensors and sensor arrays

摘要

Correlated double sampling (CDS) for magnetoresistive (MR) sensors is provided. Here the MR sensor output is sampled at two closely spaced times. The first sample is MR signal+baseline+noise and is sampled when the modulated magnetic field is non-zero. The second sample is baseline+noise only because it is sampled when the modulated magnetic field is zero. The difference between the first and second samples will have significantly reduced low frequency noise and baseline cancellation. Modulation of the electrical bias provided to the MR sensor can be used to provide a baseline signal for temperature compensation. In a second aspect, we provide MR sensor arrays having input and output multiplexing and demultiplexing for row and column line selection, in combination with a per-sensor switch to prevent noise accumulation and bandwidth reduction from idle MR sensors.