Planning to use AD8609 for pH application, which needs an amplifier with very high input impedance and low bias current. Couldn't find the impedance information in AD8609 datasheet.
Thanks Chris, that actually helps. I am doing a pH interface design, so the input impedance is very critical as I will have to interface pH glasses with impedance up to 2Gohms. Major design decisions of selecting an Opamp are low bias current, low DC offset and it has to be a duel power opamp. Power consumption is not critical for this application.