23.7 A BJT-Based Temperature Sensor with $\pm 0.1^{\circ}\mathrm{C}(3\sigma)$ Inaccuracy from -55°C to 125°C and a 0.85pJ.K2 Resolution FoM Using Continuous-Time Readout

BJT-based temperature sensors are widely used due to their high accuracy over a wide temperature range with a low-cost 1-point trim. Although resistor-based sensors can achieve better energy efficiency, they typically require a 2-point trim to achieve comparable accuracy, while thermal-diffusivity based sensors achieve superior accuracy at the cost of energy efficiency [1]. This paper presents a BJT-based temperature sensor that achieves both excellent accuracy and energy efficiency. To avoid the kTfC noise limitations of conventional discrete-time (OT) readout schemes [2], [3], it employs a compact continuous-time (CT) front-end. Component mismatch, which often limits the accuracy of CT front-ends [4], [5], is mitigated by a combination of dynamic element matching (OEM) and a low-cost resistor-ratio self-calibration scheme. As a result, the sensor achieves a resolution FoM of
$0.85\text{pJ}\cdot\mathrm{K}^{2}$
, and a competitive inaccuracy of
$\pm 0.1^{\circ}\mathrm{C} (3\sigma)$
from
$-55^{\circ}\mathrm{C}$
tO
$125^{\circ}\mathrm{C}$
after a 1-point trim. This makes it
$4\times$
more energy-efficient than state-of-the-art BJT-based sensors with similar accuracy [2], [4], [5].