| dc.description.abstract | As a thinking center, the cerebrum plays an important part for human and it’s also abundant with many unknown information. Besides, The signal, the compositive changes produced by cerebration, are called electroencephalogram (EEG).
On average, the signal of the EEG is very weak and it’s amplitude is around 10 mV under the cerebrum cortex. After flowing through the skull, the amplitude is reduced to 0.5~100uV. Moreover, it’s easily interfered by external factors such as the environment, the electrical appliance and the physical signal of the body. Hence, it’s extremely hard to measure.
Due to the error or the aging of components, EEG access to circuits always leads to unideal filter results. Once the aging of components is overgreat, the decreasing effects will be diminished, notch filter designed by the power 60Hz interference, especially.
The study proposes a two-channel EEG measurement, including ac-coupled front-end, amplifier, three order low pass filter and notch filter that possess low noise, low distortion and high gain. With regard to the departure of cut-off frequency cause by the aging, which can be revised to original ideal design by fine-tuning. By the way to compare simulation and measurement, we can get the verification and measure EEG signals efficiently. Conjugation with battery, it’s much easy to carry and decrease power interference. | en_US |