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 Σ?ADCs.And theni,n the second stept,he 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.