MICROPOWER CMOS TEMPERATURE SENSOR WITH DIGITAL OUTPUT

A CMOS smart temperature sensor with digital output is presented. It c onsumes only 7 mu W. TO achieve this extremely low-power consumption, the system is equipped with a facility that switches off the supply po wer after each sample. The circuit uses substrate bipolars as a temper ature sensor. Conversion to the digital domain is done by a sigma-delt a converter which makes the circuit highly insensitive to digital inte rference, The complete system is realized in a standard CMOS process a nd measures only 1.5 mm(2), In the temperature range from -40 to +120 degrees C, the inaccuracy is +/-1 degrees C after calibration at two t emperatures, The circuit operates at supply voltages down to 2.2 V.