Design of Analog and Digital Filter of Electromyography

An appropriate technique of filtering is essential in dealing with bio-signal especially electromyography (EMG) because it usually contains various noises. This paper discusses the development of a low cost analog filter circuit of surface electromyography (sEMG) as well as an infinite impulse response (IIR) digital filter. An analog filter circuit with the sallen-key active filter topology is designed base on an analytical filter design and simulation. The digital IIR filter is designed simultaneously with the analog filter by deriving the IIR filter from the resulted analog filter transfer function. Furthermore, an artificial sEMG signal generated from numerical simulation as well as recorded EMG signal from Biopac MP 160 system, the standardized laboratory equipment for physiological data acquisition, is fed to the designed filter to validate the filter reliability. The result shows that the designed digital IIR filter has a better performance compared to the analog filter represented by a quantitative root mean square error (RMSE) value resulted from the two numerical simulation tests.