Dobrev D
Centre of Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Med Biol Eng Comput. 2002 Sep;40(5):546-9. doi: 10.1007/BF02345453.
A circuit is proposed for a non-differential two-electrode biopotential amplifier, with a current source and a transimpedance amplifier as a potential equaliser for its inputs, fully emulating a differential amplifier. The principle of operation is that the current in the input of the transimpedance amplifier is sensed and made to flow with the same value in the other input. The circuit has a simple structure and uses a small number of components. The current source maintains balanced common-mode interference currents, thus ensuring high signal input impedance. In addition, these currents can be tolerated up to more than 10 microA per input, at a supply voltage of +/- 5 V. A two-electrode differential amplifier with 2 x 10 Mohm input resistances to the reference point allows less than 0.5 microA per input. The circuit can be useful in cases of biosignal acquisition by portable instruments, using low supply voltages, from subjects in areas of high electromagnetic fields. Examples include biosignal recordings in electric power stations and electrically powered locomotives, where traditionally designed input amplifier stages can be saturated.
本文提出了一种用于非差分双电极生物电位放大器的电路，该电路采用电流源和跨阻放大器作为其输入的电位均衡器，可完全模拟差分放大器。其工作原理是检测跨阻放大器输入端的电流，并使其在另一个输入端以相同的值流动。该电路结构简单，使用的元件数量少。电流源维持平衡的共模干扰电流，从而确保高信号输入阻抗。此外，在±5V的电源电压下，每个输入端的这些电流可容忍高达10微安以上。对于具有2×10兆欧至参考点输入电阻的双电极差分放大器，每个输入端允许的电流小于0.5微安。该电路在便携式仪器从高电磁场区域的受试者获取生物信号且使用低电源电压的情况下可能会很有用。示例包括在发电站和电力机车中的生物信号记录，在这些地方传统设计的输入放大器级可能会饱和。
