Design of Impedance Measuring Circuits Based on Phase-Sensitive Demodulation Technique

Author

Chen, Dixiang ; Yang, Wuqiang ; Pan, Mengchun

Author_Institution

Sch. of Mechatron. Eng. & Autom., Nat. Univ. of Defense Technol., Changsha, China

Volume

60

Issue

4

fYear

2011

fDate

4/1/2011 12:00:00 AM

Firstpage

1276

Lastpage

1282

Abstract

Impedance measuring circuits play a crucial role in an electrical impedance tomography system, in which capacitance and resistance need to be measured accurately at a high speed. Several impedance measuring circuits based on phase-sensitive demodulation (PSD) have been designed, tested, and presented in this paper. The measurement error is analyzed, and the mismatch of the measured capacitance and resistance is considered to be the main cause of the measurement error. A new impedance measuring circuit with dual-frequency PSD has been designed to solve this problem. It has been proven by experiment that this circuit can be used to measure both capacitance and resistance with an uncertainty of less than 0.5%.

Keywords

analogue multipliers; capacitance measurement; circuit testing; demodulators; electric impedance imaging; measurement errors; capacitance measurement; dual-frequency phase-sensitive demodulation technique; electrical impedance tomography system; impedance measuring circuit; measurement error; resistance measurement; Analog multiplier; dual frequency; dual mode; electrical impedance tomography (EIT); phase-sensitive demodulation (PSD);

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/TIM.2010.2084770

Filename

5618560