Electrical and Computer Engineering, University at Albany, State University of New York, Albany, NY, United States of America.
Physiol Meas. 2020 Jun 30;41(6):064002. doi: 10.1088/1361-6579/ab8f74.
EIT systems, particularly those that use a parallel, multiple source architecture, require current sources with very high output impedance. To meet this requirement, sources often use complex analog circuits and require manual or electronically-controlled adjustments. The goal is to implement a current source with simple, adjustment-free analog electronics with high effective output impedance even with significant stray impedance at its output.
The excitation provided to the voltage-to-current converter is adjusted to accommodate the current lost in the finite output and stray impedances. The adaptive algorithm uses the measured voltage and the previously-measured output and stray impedance to determine the needed current adjustment.
The structure of the source is presented along with an implementation, and experimental results that show the effectiveness of the approach for frequencies up to 1 MHz. The measured output impedance with and without the adaptive compensation are presented as well as measurements of resistive and complex loads.
The new current source has low analog complexity, operates over a wide range of frequencies, and can compensate for a significant stray shunt impedance. It can be used to implement improved parallel or serial EIT systems.
EIT 系统，特别是那些使用并行、多源架构的系统，需要具有非常高输出阻抗的电流源。为了满足这一要求，电流源通常使用复杂的模拟电路，并需要手动或电子控制调整。目标是实现具有简单、无需调整的模拟电子的电流源，即使在输出存在显著杂散阻抗的情况下，也能具有高的有效输出阻抗。
调整提供给电压-电流转换器的激励，以适应有限输出和杂散阻抗中的电流损耗。自适应算法使用测量的电压和之前测量的输出和杂散阻抗来确定所需的电流调整。
本文介绍了源的结构及其实现，并展示了该方法在高达 1 MHz 的频率下的有效性的实验结果。还展示了带有和不带有自适应补偿的测量输出阻抗，以及对电阻和复负载的测量。
新的电流源具有低模拟复杂性，在宽频率范围内运行，并且可以补偿显著的杂散并联阻抗。它可用于实现改进的并行或串行 EIT 系统。
