An Accurate All CMOS Temperature Sensor for IoT Applications

Abstract

In this manuscript an area efficient, linear, robust CMOS integrated temperature sensor circuit has been proposed in multiple technology nodes using UMC RF process for IoT and low cost SoC applications. In UMC 180nm node the proposed temperature sensor has an accuracy of ±0.4°C over 3σ variation in process and ±10% variation in supply, in the temperature range -55°C to 125°C. In 65nm node it has an accuracy of ±0.6°C over 3σ variation in process and ±10% variation in supply, in the temperature range -55°C to 125°C. The proposed design achieves a highly linear, proportional to absolute temperature (PTAT) voltage at reduced process corner dependence, using a process invariant circuit in conjunction with a supply independent biasing circuit. The supply sensitivity of the output voltage is 1100 ppm/V and spread with process is limited to ±0.6°C at UMC 180nm and ±1.5°C at 65nm technology. The proposed sensor in UMC 180nm technology occupies an area of 0.002 mm² and consumes 108μW of power. The output voltage is 136mV at room temperature (27°C) in typical corner, with a slope of 0.650mV/°C. The temperature sensor is included in a micro gyroscope application and the effect of temperature on the angular frequency at zero bias is presented.