In general, temperature compensation is a method used to adjust a system’s performance to compensate for effects caused by changes in temperature. This is an important issue in precision component manufacturing; as tolerances become tighter, the effect of temperature on component dimensions, and the need to allow for it, becomes more significant.
However, many electronic components and assemblies also show some sensitivity to temperature, and similarly need compensation measures; examples include amplifiers and oscillators. Accordingly, temperature dependent resistors, or thermistors can be used in either passive or active configurations.
A passive arrangement comprises a thermistor used within a circuit to offset that circuit’s R-T characteristic; the thermistor’s response slope negates the rest of the circuit’s, resulting in an overall flat R-T graph.
In an active arrangement, the thermistor is used as a sensing element which drives an active compensation circuit, used to manage the temperature of an entire assembly.
Knowledge and understanding of an instrument’s compensated temperature range is important in ensuring its accuracy in an application. The term refers to the temperature limits of operation for which the instrument meets its stated measurement accuracy. For example, a pressure sensor may have an accuracy of 0.25% full scale over a specified compensated temperature range of -20 to +80° C.
In a practical example, temperature compensation is used in an anemometer to ensure that the effects of air temperature fluctuations – both rapid and slow – do not compromise the linearity of wind speed measurements.