23.7 A BJT-Based Temperature Sensor with ±0.1 C(3σ) Inaccuracy from -55°C to 125°C and a 0.85pJ.K²Resolution FoM Using Continuous-Time Readout

Abstract

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 0.85textpJcdotK 2, and a competitive inaccuracy of pm 0.1 circC (3sigma) from -55 circC tO 125 circC after a 1-point trim. This makes it 4times more energy-efficient than state-of-the-art BJT-based sensors with similar accuracy [2], [4], [5].