8 ~ 24 bits. The maximum range of the DAQ is divided into
(28 - 1) ~ (224 - 1) equal spacing slots. Signal voltages that fall within a given slot will be interpreted (digitized) as the voltage representing that slot. Combined with selectable gain, the smallest voltage DAQ hardware can resolve is given by,
(Maximum Range / Gain) / (2Resolution - 1)
For a 16 bit, -10 ~ 10 Volt range, 40 dB gain DAQ card, the voltage resolution could be as small as (10 / 100) / (216 - 1) = 1.5 µV. However, in that case, the maximum allowable input should not be larger than (10 / 100) = 0.1 V.