An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor Networks

This work presents a nano-watt digital output temperature sensor featuring a supply-insensitive, self-biased current source. Second-order temperature dependencies of the MOS diode are canceled to produce a stable reference and a linear temperature-sensitive voltage. The sensor integrates a sensing u...

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Main Authors: Naveed, Jeff Dix
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Journal of Low Power Electronics and Applications
Subjects:
Online Access:https://www.mdpi.com/2079-9268/15/1/1
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author Naveed
Jeff Dix
author_facet Naveed
Jeff Dix
author_sort Naveed
collection DOAJ
description This work presents a nano-watt digital output temperature sensor featuring a supply-insensitive, self-biased current source. Second-order temperature dependencies of the MOS diode are canceled to produce a stable reference and a linear temperature-sensitive voltage. The sensor integrates a sensing unit, voltage-controlled differential ring oscillators, and a low-power frequency-to-digital converter, utilizing a resistor-less design to minimize power and area. The delay element in the ring oscillator reduces stage count, improving noise performance and compactness. Fabricated in 65 nm CMOS, the sensor occupies 0.02 mm<sup>2</sup> and consumes 60 nW at 25 °C and 0.8 V. Measurements show an inaccuracy of +1.5/−1.6 °C from −20 °C to 120 °C after two-point calibration, with a resolution of 0.2 °C (rms) and a resolution FoM of 0.022 nJ·K<sup>−2</sup>. Consuming 0.55 nJ per conversion with a 9.2 ms conversion time, the sensor was tested in a battery-less wireless sensor node, demonstrating its suitability for wireless sensing systems.
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spelling doaj-art-3147be039c784e2ea3a08a6f9d282f382025-08-20T02:11:26ZengMDPI AGJournal of Low Power Electronics and Applications2079-92682025-01-01151110.3390/jlpea15010001An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor NetworksNaveed0Jeff Dix1Department of Electrical Engineering and Computer Science, University of Arkansas, Fayetteville, AR 72701, USADepartment of Electrical Engineering and Computer Science, University of Arkansas, Fayetteville, AR 72701, USAThis work presents a nano-watt digital output temperature sensor featuring a supply-insensitive, self-biased current source. Second-order temperature dependencies of the MOS diode are canceled to produce a stable reference and a linear temperature-sensitive voltage. The sensor integrates a sensing unit, voltage-controlled differential ring oscillators, and a low-power frequency-to-digital converter, utilizing a resistor-less design to minimize power and area. The delay element in the ring oscillator reduces stage count, improving noise performance and compactness. Fabricated in 65 nm CMOS, the sensor occupies 0.02 mm<sup>2</sup> and consumes 60 nW at 25 °C and 0.8 V. Measurements show an inaccuracy of +1.5/−1.6 °C from −20 °C to 120 °C after two-point calibration, with a resolution of 0.2 °C (rms) and a resolution FoM of 0.022 nJ·K<sup>−2</sup>. Consuming 0.55 nJ per conversion with a 9.2 ms conversion time, the sensor was tested in a battery-less wireless sensor node, demonstrating its suitability for wireless sensing systems.https://www.mdpi.com/2079-9268/15/1/1fully integratedfrequency-to-digitalnano-wattsubthresholdtemperature sensorultra-low-power
spellingShingle Naveed
Jeff Dix
An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor Networks
Journal of Low Power Electronics and Applications
fully integrated
frequency-to-digital
nano-watt
subthreshold
temperature sensor
ultra-low-power
title An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor Networks
title_full An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor Networks
title_fullStr An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor Networks
title_full_unstemmed An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor Networks
title_short An Ultra-Low-Power 0.8 V, 60 nW Temperature Sensor for Battery-Less Wireless Sensor Networks
title_sort ultra low power 0 8 v 60 nw temperature sensor for battery less wireless sensor networks
topic fully integrated
frequency-to-digital
nano-watt
subthreshold
temperature sensor
ultra-low-power
url https://www.mdpi.com/2079-9268/15/1/1
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