A Sub-0.01 °C Resolution All-CMOS Temperature Sensor with 0.43 °C/−0.38 °C Inaccuracy and 1.9 pJ · K² Resolution FoM for IoT Applications

Abstract

A high resolution, acceptable accuracy and low power consumption time-domain temperature sensor is proposed and simulated in this paper based on a 180 nm standard CMOS technology. A diode stacking structure is introduced to enhance the accuracy of the temperature sensing core. To improve the resolution of the sensor, a dual-input capacitor multiplexing voltage-to-time converter (VTC) is implemented. Additionally, a low-temperature drift voltage-mode relaxation oscillator (ROSC) is proposed, effectively reducing the large oscillation frequency drift caused by significant temperature impacts on delay errors. The simulated results show that the resolution is as high as 0.0071 °C over 0∼120 °C with +0.43 °C/−0.38 °C inaccuracy and 1.9 pJ · K2 resolution FoM, consuming only 1.48 μW at a 1.2 V supply voltage.

Keywords

• time-domain temperature sensor
• high resolution
• subthreshold
• VTC
• ROSC
• time-to-digital converter (TDC)