1.5°C accurate CMOS temperature sensor with a single point trim at 85°C

Abstract

This paper presents a temperature sensor with an accuracy of 1.5°C. The paper analyzes inaccuracy of the existing temperature sensors and outlines the techinques to overcome them. The sensor is based on a CMOS current reference which is almost constant over process/corner and voltage variation. Most of the techniques known today for generating a process and voltage independent current source have very stringent constraints on sizing of the transistors. The current source proposed in the paper relaxes such constraints thus easing the portability across various technology nodes. The sensor designed in TSMC 28 nm CMOS process offers the accuracy of 1.5°C over a temperature range of −40°C to 125°C with a single point trim at 85°C. The sensor consumes a power of 90 μW of power when operating on 1.8 V supply.