A 20 nW+0.8 C/-0.8 C Inaccuracy (3) Leakage-Based CMOS Temperature Sensor With Supply Sensitivity of 0.9 C/V

This paper presents a subthreshold-leakagecurrent-based fully CMOS temperature-to-digital converter with high accuracy and supply rejection. The subthreshold current ratio is constructed by different channel lengths of the same MOSFET type, providing high accuracy and less corner dependence. In addition, the supply sensitivity is enhanced by the proposed subthreshold-leakage-current-based sensing element (SE) and the frequency ratio of two identical currents to frequency converters (CFCs). The prototype was implemented in a 180nm CMOS process. It achieves an inaccuracy of +/- 0.8 degrees C (3 sigma) from 0 degrees C to 100 degrees C after two-point calibration with a resolution of 120mK. Over a wide supply range from 0.8V to 1.6V, the temperature sensor shows a supply sensitivity of 0.9 degrees /V at 30 degrees C. Over the temperature range of 0-100 degrees C, the power supply sensitivity is smaller than 3.4 degrees C/V. Operating at 1V, the sensor has a power consumption of 20nW at 30 degrees C, leading to an FoM of 14.4 pJ center dot K-2.