A Novel Method of Linearizing Thermistor Characteristic Using Voltage Controlled Oscillator

• Main Authors: Narayana K. V. L, Bhujanga Rao A.
• Format: Article
• Language: English
• Published: IFSA Publishing, S.L. 2012-01-01
• Series: Sensors & Transducers
• Subjects: Thermistors; 566 Voltage controlled oscillator (VCO); LabVIEW; Temperature measurement; Linearization; Sensors
• Online Access: http://www.sensorsportal.com/HTML/DIGEST/january_2012/P_904.pdf

This paper introduces a novel way of linearizing the thermistor characteristic using Voltage Controlled Oscillator (VCO) which exhibits a linear analog temperature/frequency relation over a wide temperature range (0 0C to 120 0C) with reasonably good response linearity, reliability, and overall improved performance. Linearization is required to compensate for the inverse exponential nature of the resistance-temperature characteristic of the thermistor. A notable feature of the proposed circuit is the sensitivity in the thermistor is quite high. The efficacy of the proposed circuit is established through simulation studies and its practicality demonstrated with experimental results obtained on a prototype unit built and tested. The proposed circuit is characterized by nonlinearity of ±1 % and sensitivity of about 5 kHz/oC in the temperature range of 0 0C to 120 0C, as well as high temperature stability.