A Novel Capacitance-to-Digital Converter for Capacitive Sensors with AC Excitation |
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| Prashanth Vooka, Abhishek Ranjan, Boby George |
- Abstract:
- This paper proposes a novel, simple and high accuracy Capacitance-to-Digital Converter (CDC). Capacitive sensors have numerous industrial applications such as humidity sensing, human touch sensing, flow measurement, ice detection, etc. In most of these applications a sinusoidal excitation is employed or preferred to achieve high sensitivity and accuracy. In order to get a final digital output from a conventional bridge based circuit with a capacitive sensor, an Analog-to-Digital Converter ADC is required. CDCs wherein capacitive sensor is an integral part of a sigma-delta ADC are available but they do not employ a sinusoidal excitation and hence may not give the best output for some of the above mentioned applications. This paper presents a new dual-slope CDC that is designed to accept output from a capacitive sensor, which is excited electrically by a sinusoidal source, and provides a direct digital output proportional to change in capacitance. Such a CDC, having a distinct combination of sinusoidal excitation and dual-slope principle, is best suited for various applications as it provides high accuracy, sensitivity, immunity-to-noise and interference, etc. A prototype CDC has been developed and tested in the laboratory. Experimental results showed the practicality of the proposed scheme.
- Keywords:
- capacitive sensor, capacitance to digital converter, charge amplifier
- Download:
- IMEKO-TC4-2013-061.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC4
- Event name:
- TC4 Symposium 2013
- Title:
- 19th IMEKO TC4 Symposium Measurements of Electrical Quantities (together with 17th TC4 IWADC Workshop on ADC and DAC Modelling and Testing)
- Place:
- Barcelona, SPAIN
- Time:
- 18 July 2013 - 19 July 2013