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A wide-band AC-coupled current source for electrical impedance tomography
1Department d'Enginyeria Electrònica, Universitat Politècnica de Catalunya, Barcelona, Spain.
Physiological Measurement
|May 1, 1994
Summary
This study presents a novel wide-bandwidth current source for electrical impedance tomography (EIT). The design overcomes common issues like mismatching and saturation, enhancing EIT system performance.
Area of Science:
- Biomedical Engineering
- Electrical Engineering
- Medical Imaging
Background:
- Electrical Impedance Tomography (EIT) requires stable and accurate current sources for imaging.
- Discrete current source realizations often suffer from mismatching and temperature-induced problems.
- Existing designs may face saturation issues when using DC-blocking capacitors.
Purpose of the Study:
- To develop a wide-bandwidth current source specifically for EIT applications.
- To address and overcome limitations of conventional current source designs.
- To improve the reliability and accuracy of current injection in EIT systems.
Main Methods:
- Utilized a current-feedback amplifier (AD844) for current-conveyor implementation.
- Integrated an operational amplifier (op amp) feedback loop to enhance gain accuracy.
- Implemented DC feedback to prevent saturation and maintain low DC output voltage.
Main Results:
- Achieved a wide-bandwidth current source using the AD844 amplifier.
- Successfully mitigated mismatching and temperature-induced problems.
- Resolved saturation issues associated with DC-blocking capacitors through DC feedback.
- Demonstrated both inverting and non-inverting AC-coupled current source configurations.
Conclusions:
- The proposed current source design is suitable for EIT applications.
- The design offers improved stability, accuracy, and reliability compared to discrete realizations.
- The AC-coupled configurations provide versatile options for EIT system development.