This paper presents a sensor and its readout circuit suitable for contact-less temperature measurements. The sensor, designed employing a MEMS technology provided by STMicroelectronics, consists of a miniaturized micromachined silicon thermopile with 180-V/W responsivity, 540-kΩ output resistance, and 0.64-mm^2 active absorbing area. The interface circuit, fabricated in a standard 130-nm CMOS process, employs chopper technique in order to provide amplification of the sensor output signal, which behaves substantially as a DC, while minimizing offset and noise contributions at low frequency. Given the sensor characteristics, a single-ended architecture was preferred over the most straightforward fully-differential approach. The interface circuit reduces the offset by a factor 255, achieving an input referred offset standard deviation equal to 1.365 µV, measured across 29 samples. The thermopile sensor and the interface circuit, integrated in two separate test-chips, were characterized and extensively measured both as standalone devices and together as a system to perform contact-less temperature measurements. Adding a metal cap to the thermopile sensor in order to reduce the environmental noise, a measurement accuracy of approximately ±0:2 °C was obtained, thus verifying the system suitability for human body temperature detection.

An Integrated Micromachined Thermopile Sensor with a Chopper Interface Circuit for Contact-Less Temperature Measurements

E. Moisello;P. Malcovati;E. Bonizzoni
2019-01-01

Abstract

This paper presents a sensor and its readout circuit suitable for contact-less temperature measurements. The sensor, designed employing a MEMS technology provided by STMicroelectronics, consists of a miniaturized micromachined silicon thermopile with 180-V/W responsivity, 540-kΩ output resistance, and 0.64-mm^2 active absorbing area. The interface circuit, fabricated in a standard 130-nm CMOS process, employs chopper technique in order to provide amplification of the sensor output signal, which behaves substantially as a DC, while minimizing offset and noise contributions at low frequency. Given the sensor characteristics, a single-ended architecture was preferred over the most straightforward fully-differential approach. The interface circuit reduces the offset by a factor 255, achieving an input referred offset standard deviation equal to 1.365 µV, measured across 29 samples. The thermopile sensor and the interface circuit, integrated in two separate test-chips, were characterized and extensively measured both as standalone devices and together as a system to perform contact-less temperature measurements. Adding a metal cap to the thermopile sensor in order to reduce the environmental noise, a measurement accuracy of approximately ±0:2 °C was obtained, thus verifying the system suitability for human body temperature detection.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1279986
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