A 0.4V 280-nW frequency reference-less nearly all-digital hybrid domain temperature sensor

This paper presents a subthreshold frequency reference-less temperature sensor. Compared with the previous designs that rely on external frequency references or excessive analog blocks, this work proposes a novel subthreshold ratioed-current/delay sensor core and hybrid-domain all-digital processing technique, which eliminates the dependence on frequency reference and is scalable to technology feature size. Our sensor has been fabricated in a 65-nm CMOS process and occupies a total area of 0.022mm². Measurement results from 8 test chips have shown that the maximum inaccuracy is -1.6^oC/+1^oC across 0^oC to 100^oC with power consumption of 280-nW at 0.4V.