<abstract xmlns="http://www.w3.org/1999/xhtml"><p>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 <italic>±</italic>35 μ<italic>A</italic> with an output impedance that is more than 1 <italic>M</italic> Ω. It is possible to achieve bandwidths above 1 <italic>MHz</italic> for small load impedances. This circuit is well suited for medical applications thanks to the isolation in the optocouplers.</p></abstract>

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 μA with an output impedance that is more than 1 M Ω. It is possible to achieve bandwidths above 1 MHz for small load impedances. This circuit is well suited for medical applications thanks to the isolation in the optocouplers.

Optically isolated current source

Journal of Electrical Bioimpedance

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

{"article-title":"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...

Opamp	Opamp GBW	Sim. or Meas.	BW
TLC274	1.7	Measured	0.68
TLC274	1.7	Simulated	1.28
TS924	4	Measured	1.35
TS 924	4	Simulated	2.42
LT1214	28	Simulated	6.90

Optically isolated current source

Article Category: Articles

Publicado en línea: 11 dic 2015

Páginas: 18 - 21

Recibido: 01 dic 2015

DOI: https://doi.org/10.5617/jeb.2571

Palabras clave
Current source, isolation, optocoupler

© 2015 F. J. Pettersen and J. O. Høgetveit, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

Fig. 3

Measured and simulated bandwidths, unit for all parameters is MHz.

Optically isolated current source

Article Category: Articles

Publicado en línea: 11 dic 2015

Páginas: 18 - 21

Recibido: 01 dic 2015

DOI: https://doi.org/10.5617/jeb.2571

Palabras claveCurrent source, isolation, optocoupler

© 2015 F. J. Pettersen and J. O. Høgetveit, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Fig. 2

Fig. 3

Measured and simulated bandwidths, unit for all parameters is MHz.

Palabras clave
Current source, isolation, optocoupler