A Fully Integrated Miniatured Capacitive Angle Encoder based on MEMS Fabrication and ASIC Implementation

The design and fabrication of a fully integrated miniatured capacitive angle encoder utilizing MEMS fabrication and ASIC technology are presented. A sensitive structure with 27.5mm outer diameter is designed and fabricated by MEMS technology. It is integrated with an ASIC, which enables angle calculation and compensation. The ASIC is designed in an analog-digital hybrid architecture to achieve low power consumption as well as a small footprint consisting of a charge to voltage converter with capacitance cancellation array, a sigma-delta modulator (SDM) with a 3-bit quantizer, and Cortex-M3 digital cornel. The measurement result reveals that the resolution is 0.002° and the accuracy over the full absolute range is 0.012°, indicating that the encoder has considerable potential for use in high-precision and miniatured applications.