A 13-bit Temperature Sensor With a ±1.45 °C (3σ) Inaccuracy From –55 °C to 125 °C
Hua Fan, Bowen Wu, Hongrui Che, Ruoyu Yu, Hongquan Wang, Haizhu Wang, Ce Wang, Antonio Aprile, Edoardo Bonizzoni, Haishi Wang, Quanyuan Feng, Qi Wei · IEEE Sensors Journal · 2024
This article introduces a bipolar junction transistor (BJT)-based CMOS temperature-to-digital converter (TDC) that demonstrates an accuracy of${\pm } 1.45~^{\circ }$C (3$\sigma $) within a temperature range of$- 55~^{\circ }$C to$125~^{\circ }$C, achieved without the need for calibration. This result is attributed to the implementation of a second-order curvature compensation technique, which utilizes a switched-capacitor integral circuit within the bandgap reference circuit. This approach effectively mitigates higher order reference voltage errors, enhancing overall precision. In addition, this article incorporates dynamic element matching (DEM) and autozeroing techniques, applied in successive amplification stages, to minimize errors originating from current mirror mismatches and operational amplifier offset voltages, respectively. The described BJT-based sensor features a 13-bit successive-approximation-register analog-to-digital converter (SAR ADC), comprising a 5-bit capacitive array and an 8-bit resistor-capacitor hybrid array, designed to monitor and digitally record temperature data. The proposed design operates within a supply voltage range of 2.7–5.5 V and is realized using a 0.6-$\mu $m BJT process, ultimately achieving a resolution of 29.7 mK.