Spinelli Enrique M, Mayosky Miguel A
Laboratorio de Electrónica Industrial Control e Instrumentación, Facultad de Ingeniería, Universidad Nacional de La Plata and Consejo Nacional de Investigaciones Científicas y Técnicas CC 91, (1900) La Plata, Argentina.
IEEE Trans Biomed Eng. 2005 Aug;52(8):1436-42. doi: 10.1109/TBME.2005.851488.
In this paper, an analysis of power line interference in two-electrode biopotential measurement amplifiers is presented. A model of the amplifier that includes its input stage and takes into account the effects of the common mode input impedance Z(C) is proposed. This approach is valid for high Z(C) values, and also for some recently proposed low-Z(C) strategies. It is shown that power line interference rejection becomes minimal for extreme Z(C) values (null or infinite), depending on the electrode-skin impedance's unbalance deltaZ(E). For low deltaZ(E) values, minimal interference is achieved by a low Z(C) strategy (Z(C) = 0), while for high deltaZ(E) values a very high Z(C) is required. A critical deltaZ(E) is defined to select the best choice, as a function of the amplifier's Common Mode Rejection Ratio (CMRR) and stray coupling capacitances. Conclusions are verified experimentally using a biopotential amplifier specially designed for this test.
本文对两电极生物电位测量放大器中的电源线干扰进行了分析。提出了一种放大器模型，该模型包括其输入级，并考虑了共模输入阻抗Z(C)的影响。这种方法对于高Z(C)值以及一些最近提出的低Z(C)策略都是有效的。结果表明，根据电极 - 皮肤阻抗的不平衡量deltaZ(E)，对于极端的Z(C)值（零或无穷大），电源线干扰抑制会变得最小。对于低deltaZ(E)值，通过低Z(C)策略（Z(C)=0）可实现最小干扰，而对于高deltaZ(E)值，则需要非常高的Z(C)。根据放大器的共模抑制比（CMRR）和杂散耦合电容定义了一个临界deltaZ(E)来选择最佳方案。使用专门为此测试设计的生物电位放大器通过实验验证了结论。
