A CMOS-based Temperature Sensor with Subthreshold Operation for Low-voltage and Low-power On-chip Thermal Monitoring

Abstract

A CMOS-based temperature sensor is proposed for low-voltage and low-power on-chip thermal monitoring applications. The proposed temperature sensor converts a proportional to absolute temperature (PTAT) current to a PTAT frequency using an integrator and hysteresis comparator. In addition, it operates in the subthreshold region, allowing reduced power consumption. The proposed temperature sensor was fabricated in a standard 90 nm CMOS technology. Measurement results of the proposed temperature sensor show a temperature error of between -0.81 and + 0.94(circle)C in the temperature range of 0 to 70(circle)C after one-point calibration at 30(circle)C, with a temperature coefficient of 218 Hz/C-circle. Moreover, the measured energy of the proposed temperature sensor is 36 pJ per conversion, the lowest compared to prior works.