Hi,
The question of input current noise density was usefully answered here: https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1269686/opa189-input-current-noise-density-spectrum-of-opax189?tisearch=e2e-sitesearch&keymatch=input%252520current%252520noise#
Two related questions that are relevant especially at low frequency:
- What is the linearity, or just stability, of the input offset current w.r.t., to common mode input voltage.
- What is the temperature coefficient of input offset current.
I suspect the answer may well be that they are low, but given the current noise is orders of magnitude lower than the total current, it can't be taken for granted - even modest values might have more practical effect than noise.
(In both cases, the offset current is much more relevant than the bias current if it makes any difference - with proper impedance matching the bias cancels and only offset contributes to the noise.)
