基于过采样的通用生物电检测系统的实现

生物电信号的检测要求系统具有极高的分辨率、宽动态范围以及强噪声抑制能力．为此．以18位800kSPS的SAR ADC AD7674为核心，结合过采样技术构造生物电检测系统．过采样的抽取分两步进行：第一级抽取，通过设置不同的过采样率使系统的分辨率达到与EAADC相当的水平；第二级抽取，则利用过采样的低通效应，使主频接近的生理信号得以分离．过采样技术的引用使系统电路极大简化，并且系统的性能参数软件可调，具有更高的灵活性．将该系统应用于幅值相差悬殊的心电和胃电的同步检测，取得了良好的效果，说明系统具有较好的通用性，足以满足多种生物电信号检测的需要．

Realization of an All-Purpose Bioelectricity Detecting System Based on Oversampling Technique

The weakness of bioelectrical signals requires ultra-high resolution, wide input dynamic range and strong noise rejection abilities in the detecting system. Therefore, a system based on 18 bit, 800 kSPS SAR ADC AD7674 was built to measure bioelectrical signals, combined with oversampling technique. The decimation process of oversampling is divided into two steps. The aim of the first step is to improve the resolution of system, which is now nearly the same as EAADCs. And then, in the second step, the digital low-pass effect of oversampling is employed, by means of which the frequency- adjacent bioelectrical signals can be optimally separated. The utilization of oversampling technique has greatly simplified the structure of the circuit. The adjustable software parameters make the system more flexible. Human＇s ECG and EGG signals, whose amplitudes are different from each other very much, are sampled simultaneously to examine the effectiveness of the apparatus. The results show that the system is adaptable to satisfy the variety of bioelectricity collection.