Online Demodulation of Miniatured Capacitive Angular Position Sensor based on ASIC Implementation

A miniatured capacitive angle position sensor based on ASIC implementation to achieve online demodulation is proposed. The capacitive angle position sensor is utilized in many control systems for its advantageous characteristics. The challenge is to achieve high resolution and accuracy as well as to use cost-effective hardware, especially in a limited footprint. In the proposed work, the ASIC is designed in an analog-digital hybrid architecture, and an online demodulation method is utilized to achieve low power consumption as well as a small footprint. The digital phase-locked loop (DPLL) and harmonic analysis are used in the proposed sensor to demodulate and compensate for the angle position. A sensitive structure with a 20mm outer diameter is combined with the ASIC to verify the performance. The measurement result reveals that the resolution is 0.003° and the maximum nonlinear error over the full range is 0.05°, demonstrating the effectiveness of the proposed method.