High performance AC coupled Biomedical Signal Processing System using New Technique of Impedance Steering with Synchronous Sampling and A/D Conversion

This paper proposes a new method named as impedance steering to improve the frequency response of the AC coupled instrumentation amplifier (IA) which is widely used for processing of biomedical (BM) signals. The method makes use of steering a high impedance in chain of resistors used at the input of IA with balanced AC coupling to achieve very high impedance during amplification of the input voltage. This results in uniform frequency response even at the lower frequencies which is major concern for processing of BM signals. This impedance steering technique can be used at input of any IA to construct a standalone amplification system for BM signals. However, in many applications, the output of IA is digitized using high resolution A/D conversion. A new method named a synchronized sampling and A/D conversion has been proposed in this paper for such applications. This method makes use of sampling and digitization of the signal which is synchronized with the process of steering the impedances to obtain high performance AC coupled BM signal processing system. The circuit has been designed and simulated using NI Multisim software, version 12. The results obtained using this method confirms the efficacy of the method for obtaining high performance signal processing required for BM signal applications. Though the system is preliminary designed for BM application, it can be used for wide range of signal processing.