A Method for Improving Conversion Rate and Accuracy of a Capacitance-to-Digital Converter

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International Journal on Smart Sensing and Intelligent Systems

Professor Subhas Chandra Mukhopadhyay

Exeley Inc. (New York)

Subject: Computational Science & Engineering, Engineering, Electrical & Electronic

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VOLUME 7 , ISSUE 5 (December 2014) > List of articles

Special issue ICST 2014

A Method for Improving Conversion Rate and Accuracy of a Capacitance-to-Digital Converter

Prashanth Vooka / Boby George

Keywords : capacitance-to-digital converter; sinusoidal excitation; conversion rate; accuracy; capacitive sensor

Citation Information : International Journal on Smart Sensing and Intelligent Systems. Volume 7, Issue 5, Pages 1-6, DOI: https://doi.org/10.21307/ijssis-2019-088

License : (CC BY-NC-ND 4.0)

Published Online: 15-February-2020

ARTICLE

ABSTRACT

Capacitance-to-Digital Converter (CDC) ICs available in the market use square wave excitation signals but a sinusoidal excitation is preferred in various applications, such as ice detection, liquid level measurement, humidity measurement, proximity sensing, etc. A dual slope technique based CDC that employs a sinusoidal excitation has been reported recently, but it requires a large number of excitation cycles, to complete an accurate conversion. This paper presents an improved CDC that employs a specially designed method to achieve high accuracy even when a much smaller number of excitation cycles, than the reported scheme, are employed to complete the conversion. A prototype CDC has been developed and tested. In comparison with an existing CDC, the new CDC achieved a substantial reduction (by a factor of 4000) in the number of excitation cycles during integration period, resulting in an improved update rate. Worst case error observed from the prototype CDC was less than 0.24%.

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