A 12μs-Conversion, 20mK-Resolution Temperature Sensor Based on SAR ADC
Hwan-Seok Ku, Seungnam Choi, Jae‐Yoon Sim
Abstract
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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while supporting a burst operation in a conversion time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12\mu \text{s}$ </tex-math></inline-formula> after wake-up.