Precision interface electronics for a CMOS smart temperature sensor

This paper describes the interface electronics of a CMOS smart temperature sensor that is accurate to plusmn0.1degC over the full military temperature range. The sensor is fabricated in a standard CMOS process. Substrate bipolar transistors are used as temperature-sensitive devices. Precision interface electronics are used to make the most of their temperature characteristics. While the sensor is trimmed at one temperature, its accuracy over the full temperature range depends on the initial accuracy of the electronics. Dynamic offset cancellation and dynamic element matching are used to eliminate offset and gain errors. These techniques are combined with a sigma-delta ADC to obtain a readily usable digital temperature reading