LINEAR TEMPERATURE-TO-FREQUENCY CONVERTER USING AN INTEGRABLE COLPITTS OSCILLATOR.

A novel temperature-to-frequency (T/F) converter using a thermistor has been developed. The resistance of the thermistor is converted into its equivalent inductance to form the resonant circuit of a Colpitts oscillator. To linearize the T/F conversion, two resistors are used, and their values are determined so that the resultant resistance, and hence the equivalent inductance, are proportional to the square of a temperature in a specified temperature range. The converter features very high temperature resolution and small power dissipation in the thermistor. Furthermore, the whole circuit, except for the thermistor, can be fabricated in a monolithic IC form by scaling the component values.