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

Abstract

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 {it¿m} CMOS technology is presented. Based on accuracy requirements, a minimum biasing current {itIbias} for the sensor¿s bipolar core is determined. Measurement results for {itI{bias}} = 250{itnA} and CS = 1.25{itpF} (ADC sampling capacitor) are shown. An inaccuracy below ±0.15°C from ¿55°C to 125°C is achievable with a two-point calibration.