Transistor temperature measurement for calibration of integrated temperature sensors

A temperature measurement technique is presented for calibrating packaged integrated temperature sensors. An on-chip bipolar transistor is used to accurately determine the sensor's temperature during calibration. The transistor's base-emitter voltage is measured at three collector currents to find the absolute temperature while compensating for series resistances. The technique does not increase the pin count for a typical smart sensor, as the transistor can be accessed via the supply pins and an existing digital input pin. Measurements on substrate pnp's in a standard CMOS process show that the temperature can be determined with an accuracy of /spl plusmn/0.1/spl deg/C in the range of -50-130/spl deg/C.