A 33.6 $\upmu$m$^2$ 12.3 nW self-biased differential temperature sensor for thermal field monitoring

Abstract

This article presents a miniature temperature sensor for nanosystem dynamic thermal monitoring. With the compact self-biased technique pushing all the transistors into the sub-threshold region, the proposed temperature sensor exhibits the features of a small area and ultra-low power consumption. The differential cascade output scheme is also employed to eliminate dependence on amplifiers and achieve excellent noise immunity. Instead of the temperature characteristic of the threshold voltage which is strongly correlated to the process, our design’s differential output is expressed with process-independent thermal voltage and transistor sizing ratio, demonstrating outstanding linearity and robustness to CMOS process variation. The temperature sensor’s layout is implemented in standard logic cell style for convenient compatibility with the digital auto place and routing (APR) flow. Fabricated with a 55 nm CMOS process, the proposed tiny temperature sensor occupies the minimized area of 33.6 $\upmu \mathrm{m}^2$ with a maximum power consumption of 12.3 nW at 1 V supply. The supply voltage can vary from 0.4 to 1.8 V, and the max error caused by supply variation is only $\pm 0.6\,^{\circ }$C. At 1 V supply, a maximum simulation error of $+0.12\,^{\circ }$C/$-0.02\,^{\circ }$C and a measured error of $+0.7\,^{\circ }$C/$-0.45\,^{\circ }$C from $-30$ to $100\,^{\circ }$C is reported.