Linearization of Resistance Thermometers and Other Transducers

Abstract

Given a resistive transducer which responds directly or indirectly to a physical quantity x, it is shown that the relationship may be linearized by linear methods if and only if both the resistance and conductance of the transducer are concave upward as functions of x. This result applies to either deflection output or to null balance output. The application to the common temperature transducers is considered. It is shown that thermistors, linear metals (e.g., copper), and nickel can be linearized in terms of temperature, but platinum cannot be. If linearization is desired in terms of the reciprocal of absolute temperature, then all the above mentioned transducers can be linearized, including platinum. Quantitative results are obtained for all cases.

A Virtual Instrumentation Approach to Neural Network-Based Thermistor Linearization on Field Programmable Gate Array

“…Several techniques have been proposed as solutions for its nonlinearity. An early stage technique made use of simple passive elements like resistances in series or in parallel with the thermistor to linearize its output . As reported, this method suffers from narrow range of linearity and low sensitivity.…”

An Improved Linear Temperature/Voltage Converter Using Thermistor in Logarithmic Network

“…Diamond [1] has given a general treatment of the linearization problem applicable to a network consisting of a voltage source, a thermistor, and a fixed resistor. The value of a resistor in relation to the thermistor parameters is selected such that the second Manuscript derivative of the resulting output with respect to temperature vanishes at a desired reference temperature [2].…”

A novel wide range linearization approach for thermistor thermometer

“…THEORY OF PROPOSED SCHEME The conventional linearization schemes consisting of a thermistor and a fixed resistor [1] are shown in Fig. l(a) Abstract-This paper presents a new logarithmic function for response linearization of the thermistor thermometer.…”

“…l(c) and (d) is given by [8], [9] (6) it is seen that when the value of R is selected in accordance with the linearizing condition, the response nonlinearity is caused by the third and higher order derivatives. A typical plot of V ( T) versus T is depicted in Fig In the conventional method of thermistor response linearization [1], the second derivative of V ( T) in (6) is deliberately equated to zero. This approach gives a value of R in relation to the thermistor parameters.…”

“…The linearizing schemes reported so far in the literature may be conveniently put into five categories. These include: (i) a network composed of a thermistor and a fixed resistor [1], (ii) multiple use of thermistors and resistors [2], (iii) a network composed of logarithmic-divider active compensating network [3], (iv) a thermistor using a delay network [4]- [7], and (v) a thermistor-resistor combination with logarithmic network [8]- [10]. Of these, the first scheme ( Fig.…”