A 280 nW leakage-ratio-based CMOS temperature sensor with supply/clock sensitivity suppression

Abstract

This paper presents a low-cost digital temperature sensor for radio frequency identification (RFID). The proposed sensor utilizes the leakage channel current ratio of different transistors with exponential temperature dependence, which results in ultra-low-power consumption and compact size. Thanks to a dual-differential scheme, it can operate without any extra assistance from a voltage regulator or accurate clock generator. The sensor is fabricated in a standard 55 nm CMOS process, and measurement results show that the proposed design achieves an inaccuracy of +0.8/-0.75°C between -20 and 80°C while occupying a silicon area of only 5700 µm². Beneficial from the low total capacitance, the power consumption is 280 nW, and the conversion time is 37 ms.