Abstract
In this paper, an interface circuit for a three-axis digital tunneling resistance-type magnetic sensor in a standard 0.5µm CMOS technology is presented. The weak signal detection is achieved by the chopper instrumentation amplifier. The conversion between analog and digital is achieved by the fully differential fourth-order forward Sigma-Delta modulator. The output zero-bias of magnetic sensor is corrected by digital auto-offset circuit. The design and fabrication of tunneling resistance-type magnetic sensor interface ASIC with digital output have been achieved by the research. The performance of magnetic sensor is shown as below: the sensor is at 5V operating voltage, the value of consumption is only 120mW; the nonlinear of the sensor is 0.1%FS; the zero reference output is less than 10nT; the equivalent input noise density is less than 0.13nT/Hz1/2(at 10Hz).
