This paper presents an ultra-low power, high accuracy CMOS smart temperature sensor for clinical temperature monitoring applications. The proposed sensor trades off the sensing range and the conversion speed with improved accuracy and power consumption. The sensor consists of a power optimized analog frontend and a delta-sigma analog-to-digital converter (ΔΣADC) with dynamic element matching (DEM), as well as a modified gain stage to optimize the sensing range and relax the resolution requirement. Using a standard 0.18μm CMOS technology, the achieved accuracy and conversion speed after one-point calibration from 27°C to 47°C are ±0.1°C and 2 sample/s, respectively, while consuming only 1.1μW power. © 2013 IEEE.