A 12μs-Conversion, 20mK-Resolution Temperature Sensor Based on SAR ADC

This brief presents a temperature sensor suitable for heavily duty-cycled wireless sensor node. To achieve both a fine resolution and a fast conversion time, the proposed temperature sensor embeds a RC network in a 16-bit residue-integrated successive approximation register (SAR) analog-to-digital conversion (ADC). A poly resistor is connected in series with the capacitor digital-to-analog converter (DAC) to develop a temperature-dependent ADC input. The proposed temperature sensor, implemented in 180nm CMOS, achieves a resolution of 20mK in a range of −30-to-100°C. It shows a resolution figure-of-merit of 3pJ.K ² while supporting a burst operation in a conversion time of $12\mu \text{s}$ after wake-up.