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Open AccessArticle

Low Cost Autonomous Lock-In Amplifier for Resistance/Capacitance Sensor Measurements

1
Group of Electronic Design I3A, Zaragoza University, Pedro Cerbuna 12, 50009 Zaragoza, Spain
2
Department of Electronics, National Institute for Astrophysics, Optics and Electronics, Luis Enrique Erro 1, Puebla 72840, Mexico
3
Independent Research Professor, UVM Puebla, Camino Real San Andrés Cholula 4002, Puebla 72810, Mexico
*
Author to whom correspondence should be addressed.
Electronics 2019, 8(12), 1413; https://doi.org/10.3390/electronics8121413
Received: 24 October 2019 / Revised: 20 November 2019 / Accepted: 22 November 2019 / Published: 26 November 2019
(This article belongs to the Special Issue Low-Voltage Integrated Circuits Design and Application)
This paper presents the design and experimental characterization of a portable high-precision single-phase lock-in instrument with phase adjustment. The core consists of an analog lock-in amplifier IC prototype, integrated in 0.18 µm CMOS technology with 1.8 V supply, which features programmable gain and operating frequency, resulting in a versatile on-chip solution with power consumption below 834 µW. It incorporates automatic phase alignment of the input and reference signals, performed through both a fixed -90° and a 4-bit digitally programmable phase shifter, specifically designed using commercially available components to operate at 1 kHz frequency. The system is driven by an Arduino YUN board, thus overall conforming a low-cost autonomous signal recovery instrument to determine, in real time, the electrical equivalent of resistive and capacitive sensors with a sensitivity of 16.3 µV/Ω @ εrS < 3 % and 37 kV/F @ εrS < 5 %, respectively.
Keywords: Lock-in Amplifiers; Phase shift adjustment; Programmable circuits; Low-cost sensors; Real time monitoring; Arduino Lock-in Amplifiers; Phase shift adjustment; Programmable circuits; Low-cost sensors; Real time monitoring; Arduino
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MDPI and ACS Style

Maya, P.; Calvo, B.; Sanz-Pascual, M.T.; Osorio, J. Low Cost Autonomous Lock-In Amplifier for Resistance/Capacitance Sensor Measurements. Electronics 2019, 8, 1413.

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