An energy-efficient BJT-based temperature sensor with a continuous-time readout

Master thesis (2021)

Authors

N.G. Toth Electrical Engineering, Mathematics and Computer Science

Contributors

K.A.A. Makinwa Microelectronics (supervisor 1)
S. Pan Electronic Instrumentation - EEMCS (supervisor 2)
Faculty
Electrical Engineering, Mathematics and Computer Science
Copyright: © 2021 Nandor Toth
Temperature Sensor BJT-based TDC Continuous-Time
More Info
expand_more

Published Date

20-10-2021

Language

English

Reuse Rights

Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.

Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

This thesis presents an energy-efficient high-accuracy temperature sensor that combines a BJT front-end with a continuous-time readout circuit. Its front-end is based on PNP transistors, which, compared to NPNs, are more widely available in CMOS processes and less sensitive to stress. In this design, proportional-to-absolute-temperature (PTAT) and complementary-toabsolute-temperature (CTAT) currents are created by forcing ΔVBE and VBE over two resistors
of the same type, after which their ratio is digitized by a continuous-time Delta-Sigma Modulator (CTDSM). As a result, the sampling noise present in traditional switched-capacitor (SC) modulators is eliminated, which improves the sensor’s energy efficiency. High accuracy is achieved by the liberal use of chopping and dynamic element matching techniques. Fabricated in a 0.18µm CMOS process, the sensor achieves a 0.15°C (3σ) inaccuracy over the industrial temperature range (-45°C to 85°C) after a 1-point temperature calibration. It also achieves a 1.24mK resolution in 56.3ms, while consuming only 16µW. This corresponds to a state-of-theart resolution Figure-of-Merit (FoM) of 1.4pJ°C2.