A BJT‐Based Temperature Sensor With 58 pJ·K ² FOM and ± 0.6°C Inaccuracy From −40 to 125°C

ABSTRACT In this paper, a CMOS temperature sensor with high precision and fast response customized for temperature monitoring in power systems is presented. Substrate p‐n‐p bipolar transistor (BJT) is used as the temperature‐sensitive device to generate temperature‐dependent voltage. The readout circuit consists of a dynamically second‐order one‐bit sigma‐delta (Σ∆) analog‐to‐digital converter (ADC), realizing a digital representation of temperature. To mitigate the process variation and mismatch, chopper stabilization (CS) and dynamic element matching (DEM) techniques are used in the temperature sensing front end. The digital back end implements curve fitting and calibration, with fine‐tuning of the proportional factor to achieve digital curvature correction. The temperature sensor is implemented in a standard 0.18‐μm CMOS process, with a layout area of 0.05 mm 2 , and draws a 21.4‐μA total current from a 3.3‐V supply. After single‐point calibration, an inaccuracy of 0.73% and a resolution of 20 mK are achieved from −40 to 125°C, resulting in a resolution figure of merit (FOM) of 58 pJ·K 2 .