A 550μm2 CMOS temperature sensor using self-discharging P-N diode with ±0.1°C (3σ) calibrated and ±0.5°C (3σ) uncalibrated inaccuracies

Abstract

This work presents a CMOS temperature sensor designed specifically for distributed thermal monitoring systems of high-performance system-on-chips (SoCs). The sensor uses the temperature-dependent reverse-bias current of a p-n diode to monitor on-chip thermal profile. It occupies a small footprint of 550μm² in a 0.18μm process. The compact size of the sensor allows its usage as a “standard cell" at different on-chip coordinates to monitor localized heating due to potential hotspots on the SoC die. The sensor demonstrates measurement inaccuracies of ±0.1°C (3σ) with calibration, and +0.5°C (3σ) without any calibration, over 35°C-100°C measured temperature range. It consumes 4μW from a single 1.8V supply.