High-Precision Low-Power Interface Circuit for Two-Dimensional Integrated Magnetic Switches

This paper proposes a high-precision low-power interface circuit for two-dimensional (2D) integrated magnetic switches that can detect 2D magnetic fields and output 5 V CMOS digital signals. The interface circuit combines chopper stabilization and output offset storage technology to effectively suppress the offset of the entire signal chain and significantly improve detection accuracy. Additionally, an architecture-level signal processing algorithm is proposed, which not only realizes full polarity detection of the magnetic field at a low cost but also realizes switch detection of multi-dimensional magnetic fields in the interface circuit without additional processing. Furthermore, the circuit provides flexible adjustment of both switch trip thresholds and hysteresis windows through 4-bit off-chip trimming codes, which greatly enhances the universality of the interface circuit. This chip is implemented using 180 nm BCD technology with a chip area of 1.18 mm2. The measurement results show that the interface circuit can simultaneously process 2D input signals with a resolution of less than 85 μV. In addition, through a 4-bit trim code, the interface circuit can adjust the switch trip threshold in the range of 0–13.52 mV and the hysteresis interval in the range of 0–7.32 mV. The average current consumption of the chip is 6.757 μA.