Highly-Stable Electronic Sensor Interface for Capacitive Position Measurement

Abstract:

This paper presents capacitive sensor interface with very good stability, small thermal drift and high resolution. The measurement principle is based on a charge amplification and multi-slope conversion which utilizes stable resistors as reference components. Five capacitance ranges from 5 pF to 100 pF can be selected. Based on previous works, a so-called "zoom-in" technique is implemented for sensors with small variation of their capacitance, thus significantly extending the signal-to-noise ratio. The conversion time can be less than 100 μs, the temperature stability with offset cancellation is 2 ppm/K, and the dynamic range using "zoom-in" is 18.5 bits. The 1/f noise corner of the converter with noise floor of 0.1 fF is 20 mHz which indicates very good long-term stability. These characteristics make the interface suitable solution for wide range of industrial and scientific applications, including positioning systems and transfer of length standards with sub-nanometer accuracy.

• Periodical: Key Engineering Materials (Volume 613)
• Pages: 51-57
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.613.51
• Online since: May 2014
• Authors: Roumen Nojdelov*, Stoyan Nihtianov
• Keywords: Capacitive Sensor Interface, Resolution, Stability, Zoom-In

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