[ron_87]

EEG in microvolts, if ADC 12 bits, then reference for ADC should be in millivolts

[mlyle]

He mentions active probes. Active probes have amplification.

As his link makes clear, your ADC just needs enough resolution to measure the signal when the (amplified) offset voltages don't saturate it.

[ron_87]

yes, I told about digital EEG device from this website. To clarify analog device, I need a little more time