Abstract: An analog-to-digital converter includes a constant current source that alternately charges and discharges the capacitor between predetermined levels. The difference between the rate of charging and the rate of discharging of the capacitor provide information permitting a digital representation of the input signal. The single current source operates without change during the charging and discharging of the capacitor and has temperature compensation that eliminates potential errors due to instabilities in the ambient temperature.

Abstract: A voltage reference supply circuit is described that provides temperature compensation over a wide range of temperatures. The circuit includes a plurality of thermistor temperature dependent elements and these thermistor elements are utilized to compensate for the variation in the reference potential voltage of the Zener diode. The compensation is provided by determining the output voltage as a function of the circuit parameters and by varying pre-established resistive values in known ranges until the variations in the output voltage with temperature have been reduced below a predetermined value over the entire prescribed temperature range. Using this procedure, a variation in output voltage over the temperature range of -55.degree. C. to +125.degree. C. can be held within 50 parts per million.