CMOS Single-Chip Electronic Compass With Microcontroller

We present a CMOS single-chip electronic compass sensor including the complete digital signal processing for accurate heading calculation. The device's analog part consists of Hall- based three-axis magnetic field transducer with integrated magnetic concentrator that operates as a passive magnetic amplifier. The analog amplification chain features a gain of up to 20 000. A true-12-bit extended counting ADC converts the amplified magnetic field signals into the digital domain, where a 16-bit microcontroller calculates the heading information and outputs it via an SPI interface. The compass sensor is realized in 0.35 mum low-voltage CMOS technology plus a simple batch processing step for deposition of a metal layer. The compact die size of 2.3 mm times 2.8 mm allows for packaging into a standard 4 mm times 5 mm times 1 mm surface-mount plastic package. The heading resolution is better than 0.5deg, and the accuracy better than plusmn2deg.