Design Of a High Gain Three-Stage CMOS Operational Amplifier for EEG Signal Processing

Recently, research on brain science has led to rapid development in Electroencephalography (EEG) signal processing. However, it is really hard to capture, amplify and measure the EEG signals from the human brain during the signal acquisition and amplification. Therefore, this paper introduces a newly-designed high gain three-stage CMOS operational amplifier to measure and amplify the EEG signals precisely. The main circuit structure is built in CoolSpice with the TSMC 0.18um CMOS technology. During the simulation in CoolSpice, the open-loop DC gain reaches to 90.04dB and its power consumption is around 19.8 mW. With the help of the frequency compensation applied in the circuit, the bandwidth of the op-amp achieves to 363Hz, which is able to amplify all sorts of EEG signals and measure them, and the phase margin with the value of 177 degrees, making the circuit system stable. This three-stage op-amp makes its circuit system stable and avoids the unnecessary oscillations during the EEG signal amplification, which lead to a precise measurement on EEG signals and provide the precise diagnosis for the patients.