Current-conveyor-based wide-band current driver for electrical impedance tomography

Rao, Arun; Murphy, Ethan K.; Shahghasemi, Mohsen; Odame, Kofi

doi:10.1088/1361-6579/ab0c3c

Cited by 14 publications

(9 citation statements)

References 28 publications

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“…Also, out of the twenty channels, four are used for testing purposes and therefore the system has sixteen functional channels. A current-conveyorbased current driver (described in [91]) receives its sinusoidal input voltage generated by an off-chip DDS. As shown in Fig.…”

Section: Integrated Eit Systemsmentioning

confidence: 99%

Electrical Impedance Tomography for Biomedical Applications: Circuits and Systems Review

Hanzaee

Jiang

et al. 2021

IEEE Open J. Circuits Syst.

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There has been considerable interest in electrical impedance tomography (EIT) to provide low-cost, radiation-free, real-time and wearable means for physiological status monitoring. To be competitive with other well-established imaging modalities, it is important to understand the requirements of the specific application and determine a suitable system design. This paper presents an overview of EIT circuits and systems including architectures, current drivers, analog front-end and demodulation circuits, with emphasis on integrated circuit implementations. Commonly used circuit topologies are detailed, and tradeoffs are discussed to aid in choosing an appropriate design based on the application and system priorities. The paper also describes a number of integrated EIT systems for biomedical applications, as well as discussing current challenges and possible future directions.

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Section: Integrated Eit Systemsmentioning

confidence: 99%

Electrical Impedance Tomography for Biomedical Applications: Circuits and Systems Review

Hanzaee

Jiang

et al. 2021

IEEE Open J. Circuits Syst.

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“…A current conveyor-based current driver was proposed in [7] with an output current in the frequency range of 100 Hz to 10 MHz. The design is based on buffering the applied sinusoidal voltage across a resistor and converting it to current.…”

Section: Introductionmentioning

confidence: 99%

“…Using a cascode structure for the driver requires a relatively high voltage supply and consequently larger power consumption. The design in [7] uses 3.3 V supply voltage and generates 1.2 mA current.…”

Section: Introductionmentioning

confidence: 99%

A Low-Power Recursive I/Q Signal Generator and Current Driver for Bioimpedance Applications

Hanzaee

Neshatvar

Rahal

et al. 2022

IEEE Trans. Circuits Syst. II

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This brief presents a power-efficient quadrature signal generator and current driver application-specific integrated circuit (ASIC) for bioimpedance measurements in an electrical impedance tomography system for monitoring lung function. The signal generator is realized by a digital recursive signal oscillator with the ability of generating quadrature signals over a wide frequency range. The generated in-phase signal is applied to a current driver. It uses a balanced current-mode feedback architecture that monitors the output current through a feedback loop to minimize common-mode voltage build-up at the injection site. The quadrature signals can be used for I/Q demodulation of the measured bioimpedance. The ASIC was designed in TSMC 65 nm technology occupying an area of 0.21 mm 2 . The current driver can generate up to 0.7 mAp-p current up to 200 kHz and consumes 2.7 mW power using ±0.8 V supplies.

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“…By design, the main advantage is the limited and adjustable current, with the result that maximum allowable current limits can inherently be achieved. Different current source topologies for floating and grounded loads exist like operational transconductance amplifier, mirrored current-conveyor [ 10 , 11 ], load-in-the-loop, Tietze and Howland topologies [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Bandwidth and Common Mode Optimization for Current and Voltage Sources in Bioimpedance Spectroscopy

Menden

Matuszczyk

Leonhardt

et al. 2021

Journal of Electrical Bioimpedance

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Bioimpedance measurements use current or voltage sources to inject an excitation signal into the body. These sources require a high bandwidth, typically from 1 kHz to 1 MHz. Besides a low common mode, current limitation is necessary for patient safety. In this paper, we compare a symmetric enhanced Howland current source (EHCS) and a symmetric voltage source (VS) based on a non-inverting amplifier between 1 kHz and 1 MHz. A common mode reduction circuit has been implemented in both sources. The bandwidth of each source was optimized in simulations and achieved a stable output impedance over the whole frequency range. In laboratory measurements, the output impedance of the EHCS had its -3 dB point at 400 kHz. In contrast, the VS reached the +3 dB point at 600 kHz. On average over the observed frequency range, the active common mode compensation achieved a common mode rejection of -57.7 dB and -71.8 dB for the EHCS and VS, respectively. Our modifications to classical EHCS and VS circuits achieved a low common mode signal between 1 kHz and 1 MHz without the addition of complex circuitry, like general impedance converters. As a conclusion we found VSs to be superior to EHCSs for bioimpedance spectroscopy due to the higher bandwidth performance. However, this only applies if the injected current of the VS can be measured.

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Current-conveyor-based wide-band current driver for electrical impedance tomography

Cited by 14 publications

References 28 publications

Electrical Impedance Tomography for Biomedical Applications: Circuits and Systems Review

Electrical Impedance Tomography for Biomedical Applications: Circuits and Systems Review

A Low-Power Recursive I/Q Signal Generator and Current Driver for Bioimpedance Applications

Bandwidth and Common Mode Optimization for Current and Voltage Sources in Bioimpedance Spectroscopy

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