Bounds for Thermistor Compensation of Resistance and Conductance

This paper shows how to compensate the exponential relation between thermistor resistance and temperature: 1) by means of two constant resistances, so that the compensated resistance becomes an S curve winding around an oblique straight line; and 2) by means of three constant resistances, so that the compensated conductance becomes such an S curve. Formulas are given for the constant resistances so that the errors of the S curve approximations to the oblique lines do not exceed preassigned tolerances. The first type of compensation is used to compensate a component whose resistance increases linearly with temperature, so that the resistance of the compensated component remains constant within a preassigned tolerance throughout a preassigned temperature range of operation. The second type of compensation is applicable to temperature measurement.