计算机控制的多导心电隔离测量系统的共模抑制性能设计

The design of the common mode rejection performance in the isolated computer-controlled multichannel ECG systems

本文讨论计算机控制的多导心电隔离测量系统共模抑制性能设计的理论和实际问题。隔离系统的输入端共模干扰电压远高于接地系统的情况,对其抗共模干扰性能的分析方法也有别于对接地系统的分析方法。我们首先分析在模拟隔离技术中前放设计、隔离电源质量及隔离级前后增益分配对共模抑制比的影响,进而说明数字隔离技术的优点和实际应用中应注意的问题。最后以一个64导心电体表等电位图测量系统为例,说明本文所述原则的实际应用。

ABSTRACT This paper deals with theoretical and practical problems concerning the design of the common mode rejection performance in the isolated computer-controlled multichannel ECG systems. The common mode interference voltage in isolated systems is greater than in nonisolated systems, and the method to appreciate the ability to reject the common mode interference for isolated systems is different from that used for nonisolated systems. We discuss the influence on CMRR of the preamplifier, the isolation power supply and the isolation stage by analog isolation techniqe. We then explain the advan- tage of digital isolation technique and make some observation on the design of practical circuits. A 64 channel body surface potential mapping system is descirbed as an example for using the principles defined by this paper.