Optically isolated current source

There is a need for isolated current sources for use in selected bioimpedance measurement circuits. The requirement for good isolation is particularly important in medical settings because of safety concerns. A new circuit for producing voltage-controlled current is presented. Measurements have been...

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Bibliographic Details
Published inJournal of electrical bioimpedance Vol. 6; no. 1; pp. 18 - 21
Main Authors Pettersen, F. J., Høgetveit, J. O.
Format Journal Article
LanguageEnglish
Published Sciendo 08.08.2019
Subjects
Current source
isolation
optocoupler
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Summary:There is a need for isolated current sources for use in selected bioimpedance measurement circuits. The requirement for good isolation is particularly important in medical settings because of safety concerns. A new circuit for producing voltage-controlled current is presented. Measurements have been made on a prototype and simulations have been done on a SPICE model. The presented circuit is an H-bridge where the output devices are the output photodiodes of high-linearity optocouplers. Five operational amplifiers, four high linearity optocouplers, and passive components are used. Output current capability is 35 μ with an output impedance that is more than 1 Ω. It is possible to achieve bandwidths above 1 for small load impedances. This circuit is well suited for medical applications thanks to the isolation in the optocouplers.
ISSN:1891-5469
1891-5469
DOI:10.5617/jeb.2571