Excitation Current Source for Bioimpedance Measurement Applications: Analysis and Design

Abstract

This paper presents a systematic current source analysis using the transfer function approach. The analysis is done for the so called load-in-loop current source circuit configuration, and is generalized also for the grounded load impedance. Presence of serial and parallel parasitic components is taken into account. The analytical results are used to define criteria for the current source design and to evaluate the expressions for the source parameters estimation. Moreover the load-in-loop current source circuit is proposed in the paper, together with the current source parameters measurement system configuration. In the load-in-loop current source circuit implementation, an inverting amplifier is used with the gain G= -1. Such a choice gives theoretically only two times bigger effective intrinsic impedance value, but is usable for comparing the measured data with the theoretical results and the results of simulation. For this case good accordance of experimental results with the proposed theoretical analysis and the simulation results was achieved.