Micropower CMOS temperature sensor with digital output

A CMOS smart temperature sensor with digital output is presented. It consumes only 7 /spl mu/W. To achieve this extremely low-power consumption, the system is equipped with a facility that switches off the supply power after each sample. The circuit uses substrate bipolars as a temperature sensor. Conversion to the digital domain is done by a sigma-delta converter which makes the circuit highly insensitive to digital interference. The complete system is realized in a standard CMOS process and measures only 1.5 mm/sup 2/. In the temperature range from -40 to +120/spl deg/C, the inaccuracy is /spl plusmn/1/spl deg/C after calibration at two temperatures. The circuit operates at supply voltages down to 2.2 V.

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