An electrically isolated balanced wideband current source: basic considerations and design
An electrically isolated balanced wideband current source: basic considerations and design
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电隔离平衡宽带电流源：基本考虑因素和设计
DOI：
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发表时间：
1998
影响因子：
3.2
通讯作者：
R. Heethaar
中科院分区：
文献类型：
--
作者：
H. G. Goovaerts;T. Faes;E. Raajimakers;R. Heethaar
在相对较高的频率下，通过身体或身体部位施加交流电会产生电磁杂散场，从而减少实际注入研究组织的电流量。通过使用对称配置电流源可以减少这种辐射效应。然而，这种布置的对称性取决于源相对于周围设备的杂散电容。为了最大限度地减少这些影响，需要将源与周围设备和所研究的对象电气隔离。以这种方式，减少了关于电流源的元件的杂散电容。在这样的配置中，测量系统的输入放大器的共模电压也被降低。该论文描述了宽带电流源的设计考虑和实现，该宽带电流源能够将 300μARMS 量级的交流电注入阻抗高达 1kΩ 的生物组织中。电流稳定是通过控制电路来实现的，该控制电路测量通过所研究组织的实际电流。由屏蔽和杂散电容产生的漏电流得到补偿。可用频率范围为4kHz至1024kHz，电流稳定性优于0.2%。通过使用对称的浮动电路，获得了显着减少杂散效应的配置。电流源通过两个隔离端口与其他电路连接：（1）用于载波频率的变压器耦合； (2)光耦合器，用于传输从电流测量获得的相位参考信号。可以通过利用用于传输调制信号的第三辅助隔离端口控制控制环路的参考输入来调制电流幅度。
At relatively high frequencies, the application of an alternating current through the body or a body segment results in electromagnetic stray fields which reduce the amount of current actually injected into the tissue under study. This radiation effect can be reduced by use of a symmetrical configuration current source. The symmetry of such an arrangement, however, depends on the stray capacitances of the source with respect to surrouding equipment. To minimise these effects, it is required that the source is electrically isolated from the surrounding equipment and the subject under study. In this manner stray capacitances with respect to elements of the current source are reduced. In such a configuration common mode voltages to the input amplifier of the measuring system are also reduced. The paper describes design considerations and the implementation of a wideband current source capable of injecting alternating current in the order of 300μARMS into biological tissue having impedances up to 1kΩ. Current stabilisation is obtained by means of a control circuit which measures the actual current passing through the tissue under study. Leakage currents arising from shielding and stray capacitances are compensated for. The usable frequency range is between 4 kHz and 1024 kHz and current stability is better than 0.2%. Through the use of a symmetrical, floating circuit a configuration is obtained which substantially reduces stray effects. The current source is connected to other circuits by means of two isolation ports: (1) a transformer coupling for the carrier frequency; and (2) an opto-coupler to transfer a phase reference signal obtained from current measurement. The current amplitude can be modulated by controlling the reference input to the control loop by means of a third auxiliary isolation port for transfer of the modulating signal.