A 12 bit A/D interface for a 3D magnetic sensor

This paper presents a high resolution low-power smart system for 3D magnetic held monitoring. The magnetic sensors, integrated on-chip, need a bias current of a few mA to achieve the required resolution. Nevertheless, the proposed 12 bit A/D converter allows pulsed operation of the sensors with a duty cycle as low as 4 10(-5), thus keeping the system power consumption below 1 mu W. The A/D converter operates with 500 kHz clock frequency and achieves a DNL below 0.2 LSB and an INL below 0.5 LSB in worst case simulations. A prototype of the system has been integrated in a 1.2 pm CMOS technology.