Performance of the Load-in-the-Loop Single Op-Amp Voltage Controlled Current Source from the Op-Amp Parameters

Macias, RaulBiomedical Engineering,Technical University of Catalonia,Department of Electronic Engineering (författare)

QC 20120228
In recent years, Electrical Bioimpedance (EBI) methods have gained importance. These methods are often based on obtaining impedance spectrum in the range of β-dispersion, i.e. from a few kHz up to some MHz. To measure EBI a constant current is often injected and the voltage across the tissue under study (TUS) is recorded. Due to the performance of the current source influences the performance of the entire system, in terms of frequency range, several designs have been implemented and studied. In this paper the basic structure of a Voltage-Controlled Current Source (VCCS) based on a single Op-Amp in inverter configuration with a floating load, known as load-in-the-loop current source, is revisited and studied deeply. We focus on the dependence of the output impedance with the circuit parameters, i.e. the feedback resistor and the inverter-input resistor, and the Op-Amp main parameters, i.e. open loop gain, CMRR and input impedance. After obtaining the experimental results and comparing to the theoretical and simulated ones, they confirm the design under study can be a good solution for multi-frequency wideband EBI applications because of higher values of the output impedance than 100kΩ at 1MHz are obtained. Furthermore, an enhancement of the basic design, using a current conveyor as a first stage, is proposed, studied and implemented.

Seoane, FernandoHögskolan i Borås,Institutionen Ingenjörshögskolan,Biomedical Engineering,Chalmers tekniska högskola,Chalmers University of Technology,University of Borås,School of Engineering(Swepub:kth)u1rc29r4 (författare)
Bragos, RamonBiomedical Engineering,Technical University of Catalonia,Department of Electronic Engineering (författare)
Biomedical EngineeringTechnical University of Catalonia (creator_code:org_t)

Ingår i:Journal of Physics: Conference Series: Institute of Physics Publishing Ltd.1742-65961742-6588

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