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Linearizing Dual-Slope Digital Converter Suitable for a Thermistor

Publication Type : Journal Article

Publisher : IEEE

Source : Instrumentation and Measurement, IEEE Transactions on, Volume 60, Number 5, p.1515-1521 (2011)

Keywords : Direct digital converter, dual slope digital converter, dual-slope converter, Interactive systems, Internet, inverse exponential, Linearization, logarithmic amplifier, offset correction, Resistance, resistance temperature characteristic, resistance-to-digital converter, Temperature measurement, temperature sensors, thermistor, thermistor sensor, thermistors, Video recording, Web sites

Campus : Coimbatore

School : School of Engineering

Department : Electronics and Communication

Year : 2011

Abstract : To measure temperature using a thermistor as the sensing element, linearization to compensate for the inverse exponential nature of the resistance-temperature characteristic of the thermistor is required. A linearizing dual-slope digital converter (LDSDC) that accepts a thermistor sensor as input and provides a digital output that is directly proportional to the temperature being sensed is presented here. A logarithmic amplifier at the input of the LDSDC compensates for the exponential characteristics. The conversion logic of the underlying dual-slope converter is suitably modified to implement the required inversion and offset correction and thus obtain linearization over a wide range of input temperature. The efficacy of the proposed LDSDC is established through simulation studies and its practicality demonstrated with experimental results obtained on a prototype unit built and tested. Analysis of the proffered method to identify possible sources of errors is also presented.

Cite this Research Publication : Dr. Madhu Mohan N., Kumar, V. J., and Sankaran, P., “Linearizing Dual-Slope Digital Converter Suitable for a Thermistor”, Instrumentation and Measurement, IEEE Transactions on, vol. 60, pp. 1515-1521, 2011.

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