An All-Digital Temperature Sensor with Process and Voltage Variation Tolerance for IoT Applications

Abstract

The embedded temperature sensor which monitors the hot spots of the chip had become an essential circuit for improving the reliability of the system-on-a-chip (SoC). However, most of the temperature sensors cannot resist the influence of voltage variations and results in significant temperature errors. In this paper, the relative reference modeling (RRM)-based temperature sensor is presented. The proposed temperature sensor uses a low-temperature sensitivity voltage classifier and a low-voltage sensitivity proportional to absolute temperature (PTAT) circuit to resist the voltage variations. Addition, the process variations can be eliminated after the three-point calibration. The proposed temperature sensor was fabricated in TSMC 90nm CMOS process. The measured results show that the temperature error of the proposed design is from -1.47°C to 1.40°C with supply voltage 0.9 to 1.1V.