A mixed-signal front-end ASIC for EEG acquisition system

A mixed-signal front-end ASIC for an Electroencephalogram (EEG) acquisition system is presented. It will be attached to the scalp by electrodes and detects the electrical signals from the brain, amplifies them, and converts the signals into digital data. 8 EEG channels are integrated. In each channel the EEG signals are amplified by a pre-amplifier with a gain between 10 and 1000. Following the pre-amplifier a two-stage low pass filter is applied with a selectable band of 80 Hz or 800 Hz. The whole channel has input referred noise of 2.2 μV for a signal bandwidth of 1 Hz-1 kHz. The analog to digital converter (ADC) is based on successive approximation algorithm with a resolution of 12 bit. The analog part for the ASIC consumes 3.5 mW from 1.8 V supply and occupies 4.08 mm² in 180 nm CMOS technology.