Baolab Microsystems has designed a pure CMOS Lorentz force MEMS sensor for 3D compasses. Their new 3D Digital NanoCompass has the same performance benchmarks for sensitivity, power consumption and package size as 3D compasses that uses non-standard technologies such as magneto-resistive materials or Hall-effect structures. However, the BLBC3-D NanoCompass is less expensive. It provides 5 degree heading resolution and 13-bits per axis. Commercial product will have an I2C or SPI digital serial interface and a choice of either a 3x3x0.9mm 10 pin DFN/0.5mm pitch package, which provides drop in compatibility with existing solutions, or a 2x2x0.75mm BGA package. Engineering samples of the BLBC3-D NanoCompass will be available in 2012.
The BLBC3 NanoCompass chip features integrated 3D self-calibrating magnetic sensors, analog and digital processing circuitry, A/D convertors and a configurable digital interface. By arithmetically processing the values measured by the 3-axis sensors with an external processor, the magnetic heading can be obtained.
The BLBC3-D NanoCompass is will be made using Baolab’s breakthrough NanoEMS technology. NanoEMS enables nanoscale MEMS (Micro Electro Mechanical Systems) to be built using standard high-volume CMOS lines and fully integrated monolithically with the analogue and digital electronics. The MEMS elements are defined during the normal CMOS production process within the existing metal interconnect layers of the wafer. Built in a standard CMOS process flow, NanoEMS makes it possible to manufacture the devices at a fraction of the cost.
Lorentz force sensors are used to detect the Earth’s magnetic field. The MEMS structure, a moveable aluminium plate suspended by springs, is constructed using the metal interconnect layers of the CMOS chip by etching away the Inter Metal Dielectric (IMD) using vHF (vapour HF). When a current passes through the plate, it experiences a force (the Lorentz force) proportional to the surrounding Earth’s magnetic field. The resulting displacement is measured using capacitive detection between the moveable plate and fixed electrodes around it, sensing the magnetic field in the x, y and z directions with a single NanoEMS chip.
BLBC3-D NanoCompass Features
- 3-Axis Lorentz Force magnetic field sensor
- Automatic sensitivity and offset calibration
- Automatic transition to low-power state
- Integrated master clock generator
- I2C or SPI serial digital interface
- Built-in signal conditioning, ADC and digital interface
- 2.4V – 3.6V analog supply voltage
- 1.8V (1.65V min) digital supply voltag
- Android compliant
- Available in 3mm DFN and 2mm BGA packages
More info: Baolab Microsystems