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, which is the continuation of a work presented at the International Solid State Circuits Conference (ISSCC) 2007 in San Francisco/USA [1]. The device’s analog part consists of Hall based three-axis magnetic field transducer with integrated magnetic concentrator that operates as 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 0.35um low voltage CMOS technology plus a simple batch processing step for deposition of a metal layer. The compact die size of 2.3 mm × 2.8 mm allows for packaging into a standard 4mm × 5mm × 1mm surface mount plastic package.

The heading resolution is better than 0.5 degrees and the accuracy better than +/-2 degrees.