Low-power lock-in amplifier for complex impedance measurement

Jiawei Xu, Guy Meynants, Patrick Merken

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

This paper presents a fully integrated lock-in amplifier intended for nanowire gas sensing. The nanowire will change its conductivity according to the concentration of an absorbing gas. To ensure accurate nanowire impedance measurement, the lock-in technique is implemented to attenuate the low frequency noise and offset by synchronous demodulation or phase-sensitive detection (PSD). Dual-channel lock-in amplifier also provides both resistive and capacitive information of the nanowire in separate channels. Measurement results of the resistors and capacitors show 2% resolution over 10 KΩ - 40 KΩ resistance and 3% resolution over 0.5 nF-1.8 nF capacitance. Moreover, a palladium nanowire sensor was placed in a sealed chamber filled with 10% hydrogen in nitrogen, a 28.7 KΩ to 32.1 KΩ impedance variation was measured through the lock-in amplifier by slowly decreasing the hydrogen concentration. The chip has been implemented with UMC 0.18μm CMOS technology and occupies an area of 2 mm2. The power consumption of the readout circuit is 2 mW from a 1.8V supply.

Original languageEnglish
Title of host publication3rd International Workshop on Advances in Sensors and Interfaces, IWASI 2009
Pages110-114
Number of pages5
DOIs
Publication statusPublished - 2009
Event3rd International Workshop on Advances in Sensors and Interfaces, IWASI 2009 - Trani, Italy
Duration: 25 Jun 200926 Jun 2009

Publication series

Name3rd International Workshop on Advances in Sensors and Interfaces, IWASI 2009

Conference

Conference3rd International Workshop on Advances in Sensors and Interfaces, IWASI 2009
Country/TerritoryItaly
CityTrani
Period25/06/0926/06/09

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