A BJT-Based CMOS Temperature Sensor Achieving an Inaccuracy of pm 0.45C(3) from °50°C to 180°C and a Resolution-FoM of 7.2pJ.K²at 150°C

Integrated temperature sensors for industrial digital transformation such as turbine and bearing monitoring should exhibit low power consumption and high energy efficiency with moderate inaccuracy over a wide sensing range (e.g., > 150°C) to achieve autonomous operation under a limited energy budget. Even though resistor-based temperature sensors can achieve a superior sub-pJ.K2 resolution-FoM [1], they typically require a 2-point trim together with a high-order nonlinearity correction (6th-order in [2]), inevitably burdening the processing cost. In contrast, BJT-based temperature sensors in bulk or SOI CMOS can achieve accurate sensing at high temperature with only 1-point trim and simple digital processing [3], [4]. However, they can suffer from a degraded energy efficiency at high temperature for ensuring the sensing resolution and/or accuracy (e.q., 3× increase in bias current for improving the 3-inaccuracy from pm 0.6C to pm 0.4C in [3]). This paper describes a BJT-based temperature sensor capable of wide-range operation from -50°C to 180°C. By employing a nonlinear readout and the proposed subranging, double-sampling, and constant-biasing techniques, this work achieves a high resolution-FoM over the entire sensing range (9.7pJ.K2 at room temperature and 7.2pJ.K2 at 150°C), corresponding to a 6-to-10× improvement when compared with prior BJT-based wide-range designs [3], [4]. We further employ dynamic error-correction [5] and switch-leakage compensation to effectively suppress the mismatch- and leakage-induced errors, resulting in a high precision of pm 0.46C(3).