| Desıgn Of A Multı-Channel Bıopotentıal Amplıfıer
This thesis presents the design stages of a biopotential amplifier which can be used for detection and acquisition of various biomedical signals and deals with the design problems. First, the nature and properties of some biomedical signals are expressed and the methods of detection are given. The design of relevant amplifier is explained step by step and modification of parameters are presented with the support of considerations about detection difficulties. Moreover, the factors that reduce the quality of measurement are also presented and suggestions to eliminate these factors are given with, if any, yielding negative effects. The notch filter, which constitutes the most important part of an indoor amplifier, is also explained and a new circuitry that automatically locks rejected frequency to the frequency of mains is proposed. The effect of this high quality notch filter on the acquired signals is also examined. This project also proposes a new power supply concept differing from well-known devices, i.e. accumulators, batteries which in common are desired for isolation of mains from patients as stated by medical safety standards. The theory of this power supply is explained with circuit schematics. Being realized on a PCB board, the test results of the relevant supply is also discussed in the thesis. “TDM” method is presented which is used for anolog multiplexing that yields to a reduced cost. Afterwards, analog-to-digital converter stage is explained with detailed schematics. As a final stage of the design, many suggestions are brought for the interface that is used for not only for rapid communication with a PC but also successively isolates the amplifier from outer devices. Finally, the discussion and suggestions about future designs are presented
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