Low-power and accurate operation of a CMOS smart temperature sensor based on bipolar devices and Σ̄ A/D converter

Due to the trend towards low power operation, as in autonomous systems where power constraints are very high, sensors are increasingly being required to dissipate very low power (few microwatts). In this paper, a low-power version of a smart temperature sensor in 0.7 mum CMOS technology is presented. Based on accuracy requirements, a minimum biasing current I
_bias
for the sensor's bipolar core is determined. Measurement results for I
_bias
= 250 nA and C
_S
= 1.25 pF (ADC sampling capacitor) are shown. An inaccuracy below plusmn0.15degC from -55degC to 125degC is achievable with a two-point calibration.