Linearization Circuit of the Thermistor Connection

Thermistors have found wide application in temperature measurement and control in different fields, but they exhibit a strong nonlinearity of the characteristic, which is of an exponential type. This paper investigates the possibility of creating a thermistor-based temperature sensor with frequency and analog outputs and a linearized characteristic on the basis of a 7555 timer. It is shown through simulations that the linearization of the characteristic can be achieved without connecting additional elements to the circuit but only through a choice of the parameters of the thermistor and of the frequency-determining circuit elements. The investigations conducted show a good match between the theoretically and experimentally obtained characteristics. The proposed circuit is characterized by nonlinearity of plusmn1% in a specific temperature range, as well as high temperature stability.