Integrated low-power 24-channel EEG front-end

The first integrated CMOS multichannel electroencephalogram (EEG) readout front-end, capable of extracting EEG signals from conventional AgCl electrodes without the use of any trimmed components, is presented. Each channel of the ASIC achieves better than 90 dB common-mode rejection ratio (CMRR) at 50 Hz with 50 mV DC offset between EEG electrodes. This is consistent with the presented formula describing the CMRR behaviour of the preamplifier under DC electrode offset. The front-end includes 24 channels and consumes 10.5 mW from a 3 V supply.